Memihak kayu tradisional untuk rumah Anda akan selalu menjadi pilihan pilihan dalam pemasangan papan. Namun, Anda memerlukan kontraktor berpihak pada kanan untuk membantu Anda memilih tampilan kayu terbaik dengan perawatan berpihak paling sedikit. Ada banyak jenis papan kayu yang dibuat dengan menggunakan bahan kayu sub-par. Jangan biarkan nexthellip Anda Baca lebih lanjut Layanan atap profesional dan perbaikan atap dengan harga terjangkau Jika Anda mengalami masalah kebocoran di atap, jangan menunggu untuk menghubungi kontraktor atap. Kebocoran atap yang berkepanjangan nampaknya tidak berbahaya pada awalnya, namun bisa berubah menjadi masalah serius dengan cepat. Setelah kebocoran atap yang terus-menerus dapat menyebabkan pertumbuhan jamur, langit-langit yang rusak, perabotan. Hubungi kami hari ini jika Anda membutuhkan lonceng Read More Saat mencoba mengurangi tagihan pemanas rumah Anda, tidak ada cara yang lebih baik untuk menghemat uang daripada memasang jendela vinyl atau penggantian kayu baru. Yang terpenting, dengan potongan pajak federal baru sampai 1.500 tidak ada alasan untuk tidak melakukannya. Memiliki dek yang indah akan selalu memiliki hasil positif pada nilai properti Anda. Menambahkan dek adalah cara murah untuk memperluas ruang hidup Anda. Biaya rata-rata untuk membangun sebuah dek kira-kira 7.000 dan menghasilkan pengembalian sekitar 15.000 saat menjual rumah Anda tidak terlalu buruk. Jadi pertimbangkan untuk memiliki yang lebih baik. Baca lebih lanjut Memilih kontraktor berpihak benar sangat penting dalam pemasangan papan. Apakah itu memasang vinyl berpihak pada berpihak atau benar-benar menghapus berpihak Anda saat ini untuk berpihak baru. Memiliki kontraktor berpihak profesional yang bisa memberi Anda solusi terbaik untuk pemasangan papan paling halus akan menghemat banyak sakit kepala, waktu dan tenaga kerja Read More Apa yang Pelanggan Kami Katakan Sangat senang Saya hanya ingin mengungkapkan betapa senangnya dengan atap baru kami dan Selokan mulus Mike dan pekerjanya sangat menyenangkan dan santun berada di sekitar. Aku tidak percaya seberapa cepat mereka menyelesaikan atap rumah dan garasi kita. Mereka meninggalkan tempat itu lebih bersih daripada saat mereka memulai dan melindungi semak-semak kami, tanaman seperti yang dijanjikan. Yang sangat senang dengan pemasangan atap, kami ingin mereka kembali mengganti jendela. Terima kasih Mike Lihat rumah mereka: atap Melrose MA mdash Robert Patricia Quinn, Melrose, MA MBM Construction diberi peringkat 5 5 berdasarkan 3 ulasan. Menemukan Kontraktor Tepat Seharusnya Menyakitkan Melakukan perbaikan rumah yang tepat atau proyek renovasi dapat menambahkan nilai sebenarnya ke jenis rumah apa pun, jika dilakukan dengan benar dan efisien oleh profesional yang diberi lisensi dan Tertanggung. Menggunakan bahan berkualitas tinggi yang hemat energi, menarik dan yang terpenting, bisa diandalkan seperti low vinyl vinyl berpihak. Penggantian jendela Atap sirap dan geladak khusus akan menambah nilai nyata. Dalam kebanyakan kasus, Anda dapat mengharapkan dan segera mengembalikan investasi Anda setelah perbaikan rumah dilakukan. Pilihlah kontraktor yang akan menyelesaikan pekerjaan, memandu Anda melewati setiap langkah proyek dari awal sampai akhir tanpa tambahan tersembunyi. Layanan perbaikan rumah kami telah memberi kami keunggulan di atas perusahaan remodeling rumah lainnya. Menjadi salah satu daerah penyedia layanan papan atas di dinding, atap, jendela pengganti, dan penambahan ruangan. Memberi kita daya beli yang besar melalui pemasok kita dan sebagai gantinya, bisa memberikan penghematan kepada Anda. Jadi mengapa memilih kita sebagai kontraktor renovasi rumah Anda Kami mendengarkan kebutuhan Anda. Kami tidak menggunakan penjualan dengan tekanan tinggi, atau mencoba menjual sesuatu yang tidak Anda inginkan atau inginkan. Komunikasi adalah kunci untuk semua jenis proyek remodeling dan kami ingin proyek Anda mendapatkan hasil terbaik. Anda akan mendapatkan perkiraan waktu penyelesaian proyek yang terperinci - tanpa sakit kepala Anda juga akan mendapatkan salah satu jaminan terbaik dalam bisnis perbaikan rumah, jika Anda perlu menggunakannya. Apa Jenis Layanan Perbaikan Rumah yang Anda Cari Memilih kontraktor atap yang akan bekerja untuk kepentingan terbaik Anda dan bukan pada berapa banyak keuntungan yang dapat dia hasilkan dengan memotong sudut. Sebagai kontraktor atap, kami percaya dengan menggunakan atap terbaik untuk atap rumah dan underlayment untuk memberi ketenangan pada klien kami. Untuk info lebih lanjut tentang layanan atap, kunjungi: atap datar komersial atau atap rumah Tidak semua vinil dan papan kayu sama. Pilihlah kontraktor berpihak profesional yang akan membantu Anda memahami jenis pemutaran vinyl apa yang harus dihindari, dan apa yang akan memberi Anda kemenangan terbaik untuk uang Anda dalam jangka panjang. Dari dek bertekanan bertekanan standar, dek mahoni, atau dek komposit - membuat Anda tertutup. Baca lebih lanjut tentang Deck dan Porches Deck buildersMenghadirkan Perilaku untuk Karakter Otonom Craig W. Reynolds Sony Computer Entertainment America 919 East Hillsdale Boulevard Foster City, California 94404 Keywords. Teknik animasi, lingkungan virtualinteraktif, permainan, simulasi, animasi perilaku, agen otonom, terletak, diwujudkan, reaktif, kendaraan, kemudi, perencanaan jalan, mengikuti jalan, pengejaran, penghindaran, penghindaran rintangan, penghindaran tabrakan, berkelompok, perilaku kelompok, navigasi, buatan Hidup, improvisasi. Makalah ini menyajikan solusi untuk satu kebutuhan karakter otonom dalam animasi dan permainan: kemampuan untuk menavigasi di sekitar dunia mereka dengan gaya hidup dan improvisasi. Perilaku-perilaku agresif ini sebagian besar terlepas dari ciri-ciri alat penggerak karakter146. Kombinasi perilaku kemudi dapat digunakan untuk mencapai tujuan tingkat yang lebih tinggi (Misalnya: turun dari sini ke sini sambil menghindari rintangan, mengikuti koridor ini, bergabunglah dengan kelompok karakter tersebut.) Makalah ini membagi perilaku gerak menjadi tiga tingkat. Ini akan berfokus pada tingkat menengah perilaku kemudi, secara singkat menggambarkan tingkat gerak yang lebih rendah, dan menyentuh dengan ringan pada tingkat tujuan dan strategi yang lebih tinggi. Pendahuluan Karakter otonom adalah jenis agen otonom yang ditujukan untuk digunakan dalam animasi komputer dan media interaktif seperti permainan dan virtual reality. Agen ini mewakili karakter dalam cerita atau permainan dan memiliki kemampuan untuk berimprovisasi tindakan mereka. Hal ini berlawanan dengan karakter dalam film animasi, yang tindakannya telah ditulis sebelumnya, dan terbukti secara eksplisit dalam permainan atau kenyataan maya, yang tindakannya diarahkan secara real time oleh pemain manusia atau peserta. Dalam game, karakter otonom terkadang disebut karakter non-player. Karakter otonom harus menggabungkan aspek robot otonom dengan beberapa keterampilan aktor manusia di teater improvisasi. Karakter ini biasanya bukan robot sejati, dan pastinya bukan aktor manusia, tapi berbagi beberapa sifat masing-masing. Istilah 147 agen otonom148 digunakan dalam banyak konteks, jadi berikut ini adalah usaha untuk menemukan terminologi makalah ini dalam kaitannya dengan bidang studi lainnya. Agen otonom dapat eksis secara terpisah, atau dapat ditempatkan di dunia yang dimiliki oleh entitas lain. Agen 147data mining148 adalah contoh dari yang pertama, dan pengendali untuk jaringan listrik adalah contoh dari yang terakhir. Agen yang terletak bisa reaktif (naluriah, didorong oleh stimulus) atau bisa jadi deliberatif (147intellectual148 dalam pengertian AI klasik). Seorang agen otonom dapat menangani secara eksklusif informasi abstrak (147softbot148, 147knowbot148, atau 147information agent148) atau dapat diwujudkan dalam manifestasi fisik (robot industri khas atau kendaraan otonom). Kombinasi yang terletak, reaktif, dan diwujudkan mendefinisikan beberapa kelas agen otonom yang berbeda. Kategori yang berada, agen yang diwujudkan biasanya menunjukkan robot otonom: perangkat mekanis yang ada di dunia nyata. Terkadang robot dipelajari melalui simulasi komputasi. Tapi praktik itu dipandang dengan curiga oleh orang puritan di bidang robotika karena simulasi mungkin menyimpang dari kenyataan dengan cara yang tidak terduga. Ada kelas lain yang berada, agen yang diwujudkan berdasarkan model komputasi. Makalah ini akan menggunakan istilah virtual (seperti dalam kenyataan maya) untuk menunjukkan agen-agen ini, yang bukan simulasi alat mekanis di dunia nyata, bukan agen nyata di dunia maya. (Analog dengan model berbasis fisik dalam animasi komputer.) Oleh karena itu, karakter otonom dari judul ini adalah: terletak, terkandung, reaktif, agen virtual. Istilah perilaku memiliki banyak arti. Ini bisa berarti tindakan kompleks manusia atau binatang lain berdasarkan kemauan atau naluri. Ini bisa berarti tindakan yang dapat diprediksi dari sistem mekanis sederhana, atau tindakan kompleks dari sistem yang kacau. Dalam virtual reality dan aplikasi multimedia, kadang-kadang digunakan sebagai sinonim untuk eksperimen. Dalam makalah ini istilah perilaku digunakan untuk merujuk pada tindakan improvisasi dan tindakan seperti karakter otonom. Perilaku karakter otonom bisa lebih dipahami dengan membaginya menjadi beberapa lapisan. Lapisan ini ditujukan hanya untuk kejelasan dan spesifisitas dalam diskusi yang akan menyusul. Gambar 1 menunjukkan pembagian perilaku gerak untuk karakter otonom ke dalam hierarki tiga lapisan: pemilihan tindakan. pengemudian . Dan penggerak. Pastinya pembedahan lain mungkin dilakukan. Hirarki tiga lapis yang serupa digambarkan oleh Blumberg dan Galyean Blumberg 95, mereka memanggil lapisan: motivasi. tugas . Dan motor. Perhatikan bahwa sementara hierarki perilaku yang disajikan di sini dimaksudkan agar dapat diterapkan secara luas pada perilaku gerak, ini tidak sesuai untuk jenis tindakan otonom lainnya, misalnya perilaku percakapan dari kelompok yang sama membutuhkan struktur yang berbeda secara signifikan. Gambar 1: Hirarki perilaku gerak Pertimbangkan, misalnya, beberapa koboi merawat kawanan ternak di kisaran tersebut. Seekor sapi mengembara jauh dari kawanan ternak. Bos jejak memberitahu seorang koboi untuk menjemput orang-orang yang tersesat. Si koboi berkata dengan senang hati pada kudanya dan membimbingnya ke sapi, mungkin menghindari rintangan di sepanjang jalan. Dalam contoh ini, bos jejak mewakili pilihan tindakan: mengetahui bahwa keadaan dunia telah berubah (sapi meninggalkan kawanan) dan menetapkan sasaran (mengambil yang tersesat). Tingkat kemudi diwakili oleh koboi, yang menguraikan tujuan menjadi serangkaian subgoals sederhana (mendekati sapi, menghindari rintangan, mengambil sapi). Sebuah subgoal sesuai dengan perilaku kemudi untuk tim koboi dan kuda. Dengan menggunakan berbagai sinyal kontrol (perintah vokal, taji, kendali) koboi mengarahkan kudanya ke sasaran. Secara umum, sinyal-sinyal ini mengekspresikan konsep seperti: pergi lebih cepat, berjalan lebih lambat, belok kanan, belok kiri, dan seterusnya. Kuda menerapkan tingkat penggerak. Mengambil sinyal kendali koboi146 sebagai masukan, kuda bergerak ke arah yang ditunjukkan. Gerakan ini adalah hasil dari interaksi kompleks dari persepsi visual kuda, rasa keseimbangan, dan otot-ototnya yang menerapkan torsi ke sendi kerangkanya. Dari sudut pandang teknik, berkaki penggerak adalah masalah yang sangat sulit, Raibert 91, Hodgins 95, tapi baik koboi maupun kuda itu tidak memikirkannya lagi. Makalah ini akan fokus pada kemudi, lapisan tengah hirarki perilaku. Ini akan secara singkat menggambarkan model sederhana dari lapisan penggerak, namun hanya cukup detail untuk memberikan landasan konkret untuk diskusi tentang berbagai perilaku kemudi. Akan ada beberapa pembahasan singkat tentang pemilihan tindakan, namun terutama dalam konteks menggabungkan dan memadukan perilaku dasar kemudi. Pencarian jalan adalah topik yang berkaitan dengan, namun terpisah dari, subjek makalah ini. Algoritma pencarian jalan seperti A dan Dijkstras beroperasi pada jaringan (sering mewakili grid) dan pada dasarnya memecahkan labirin. Solusi semacam itu bisa menjadi spesifikasi teknik kemudi yang dijelaskan dalam makalah ini. Sebuah analogi mungkin untuk membandingkan instruksi mengemudi tertulis untuk mendapatkan dari satu tempat ke tempat lain dengan tindakan mengendarai mobil di sepanjang rute itu. Untuk melihat-lihat jalan yang bagus lihat Reese 99. Untuk memahami dorongan dari karya ini, perlu dicatat bahwa perilaku kemudi yang dibahas di sini berhubungan dengan gerakan cepat: berjalan versus merangkak. Ini adalah gagasan informal, namun dimaksudkan untuk menyarankan bahwa kecepatan karakter yang khas relatif besar dibandingkan dengan percepatan balik maksimumnya. Akibatnya, perilaku kemudi harus mengantisipasi masa depan, dan memperhitungkan konsekuensi akhirnya dari tindakan saat ini. Pekerjaan Terkait Perilaku pengarah untuk karakter otonom menarik sejarah panjang penelitian terkait di bidang lain. Mesin otonom, servomechanisms, dan teori kontrol berakar pada tahun 1940-an seperti yang dijelaskan dalam buku Norbert Wiener146s 1948 Cybernetics, atau Control and communication in the Animal and the Machine Wiener 48. Istilah cybernetics berasal dari kata Yunani yang berarti steersman. Pada akhir 40-an, ahli neurofisiologi Gray Walter membangun penyamak robot otonom Walter 50 yang mewujudkan beberapa perilaku kemudi yang digambarkan di sini dan merupakan salah satu mesin pertama yang menunjukkan perilaku seperti kehidupan yang muncul. Pada awal 1980-an Valentino Braitenberg mengekstrapolasi prototip Walter146 ke dalam eksperimen pemikiran tentang serangkaian 147vehicles yang fantastis148 dengan perilaku Braitenberg 84 yang semakin kompleks. David Zeltzer mulai menerapkan teknik dan model dari kecerdasan buatan ke aplikasi animasi Zeltzer 83. Dan pada tahun 1987, saya menciptakan animasi Model perilaku kawanan burung menggunakan teknik yang berkaitan erat dengan yang disajikan dalam makalah ini Reynolds 87. Daftar di bawah penelitian terkait dibagi menjadi tiga kategori umum: robotika, kecerdasan buatan, dan kehidupan buatan, walaupun dalam beberapa kasus perbedaannya agak sewenang-wenang. Umumnya karya-karya ini berorientasi pada animasi sampai batas tertentu: keduanya terletak pada tumpang tindih antara animasi (atau permainan, VR, dan multimedia) dan ketiga bidang lainnya. Pekerjaan yang berhubungan dengan robotika. Rodney Brooks mempopulerkan gagasan radikal radikal untuk membangun pengendali reaktif untuk sistem robot Brooks 85. Meskipun awalnya terinspirasi oleh penelitian etis (perilaku hewan), karya Ron Arkin Arkin 87, 89, 92 berpusat pada penerapan perilaku kemudi pada robot mobile. . Penelitian Arkin146 telah menyamai sebagian besar pekerjaan yang disajikan dalam makalah ini, namun skemanya (pemetaan persepsi155) diekspresikan dalam bentuk model lapangan potensial yang bertentangan dengan pendekatan prosedural yang dijelaskan di sini. Dalam beberapa kasus, ini adalah perbedaan tanpa perbedaan, namun dalam kasus lain (seperti penghindaran rintangan), hal itu mengarah pada perilaku agen yang berbeda secara signifikan. Marc Raibert dan Jessica Hodgins keduanya mulai berkaki dalam penelitian robotika dan sekarang keduanya bekerja dalam aplikasi animasi sistem berkaki fisik yang realistis. Dalam kedua kasus tersebut, pekerjaan mereka menyentuh aspek kemudi dan perencanaan jalan dari sistem ini Raibert 91, 91b, Hodgins 95. Bekerja dengan Zapata dkk. Pada pengendali kemudi untuk robot bergerak cepat yang berfokus pada strategi yang harus menghadapi momentum dan aspek lain dari gerak mekanis cepat Zapata 1992. Maja Mataric telah bekerja secara ekstensif dalam robotika kolektif Mataric 93 dan tema utama dari karya ini adalah kemudi. Pekerjaan yang berhubungan dengan kecerdasan buatan. Ken Kahn menciptakan sebuah sistem awal yang menghasilkan animasi gerak karakter dari deskripsi cerita Kahn 79. David Zeltzer Zeltzer 83, 90 mempelopori animasi berbasis AI, mempopulerkan gagasan abstrak tentang spesifikasi gerak. Karakter yang dibuat mampu berimprovisasi gerakan kompleks, mendapatkan dari A ke B sambil menghindari rintangan statis dan aktor lainnya. Steve Strassmann146s Desktop Theatre bekerja Strassmann 1991 memperluas gagasan ini untuk memasukkan penanganan alat peraga dan penggambaran emosional. Karya animasi perilaku agen berbasis Mocircnica Costa146s Costa 90 memungkinkan karakter untuk menavigasi di sekitar rumah sambil terus-menerus menghindari rintangan. Penelitian karakter improvisasi dan dramatis, yang menyentuh perilaku kemudi, sedang berlangsung di Project Oz (dan sekarang Zoesis) oleh Joseph Bates dkk. Bates 92 dan di The Virtual Theatre Project oleh Barbara Hayes-Roth dkk. Hayes-Roth 96. Bekerja terkait dengan kehidupan buatan (dan bidang lainnya). Model boids 1987, kelompok ternak, sekolah, dan gerakan kelompok terkait Reynolds 87, membongkar perilaku kelompok yang kompleks ini menjadi tiga perilaku kemudi sederhana pada tingkat individu. Tahun berikutnya terkait perilaku kemudi untuk menghindari penghalang Reynolds 88 dipresentasikan. Pada Workshop Buatan Tahun 1987 Mitchel Resnick mempresentasikan hasil kerja pada kendaraan otonom yang diimplementasikan di Resoick LEGO LOGO 89 dan Michael Travers mendemonstrasikan alat pelacak Pertanian AGAR Animal Travers 89. (Lihat juga karya yang lebih baru oleh para penulis Resnick 93 dan Travers 94.) Perilaku pengarah adalah Elemen kunci dalam The Virtual Fishtank, sebuah instalasi multiuser VR di The Computer Museum yang dibuat oleh tim dari MIT146s Media Lab dan NearLife Resnick 98. Armin Bruderlin secara prosedural menghasilkan animasi terarah dari manusia berjalan Bruderlin 1989. Randall Beer146s disertasi tentang kecoa buatan Bir 90 Penting untuk kedalaman dan kompleksitas model neuroetologisnya. Inti dari model ini adalah implementasi saraf dari beberapa tropisme (seperti chemotaxis dan thigmotaxis) yang merupakan analog langsung dari perilaku kemudi yang dijelaskan di bawah ini. Di Wilhelms, Jane Wilhelms dan Robert Skinner menyelidiki arsitektur untuk karakter mirip kendaraan. Thalmann dkk. Menciptakan karakter animasi perilaku yang menyusuri koridor dan di sekitar rintangan yang menggunakan penglihatan seperti disimulasikan dengan rendering 3D Thalmann 90. Michiel van de Panne menciptakan pengendali untuk tugas seperti parkir paralel mobil menggunakan pencarian ruang negara van de Panne 90. G. Keith Masih memiliki Meniru kerumunan manusia yang besar dengan menggunakan model perilaku kemudi setiap individu Masih 94. Dengan menggunakan algoritma genetika yang dimodifikasi, Karl Sims secara bersamaan mengembangkan otak dan tubuh makhluk buatan untuk berbagai gaya gerak dan untuk pencarian tujuan Sims 94. Dalam pekerjaan yang pertama kali dilaporkan pada SAB94 dan diperbarui di SAB96 Cliff 96, Cliff dan Miller mengoordinasi pengejaran dan penghindaran perilaku pemangsa dan mangsa. Xiaoyuan Tu et al. Mengembangkan model biomekanika, penggerak, persepsi, dan perilaku ikan di Tu 94, 96 yang mencakup secara dramatis realistis dan realistis, termasuk gerakan berbasis fisik, perilaku kemudi, dan sistem berbasis etologis untuk seleksi tindakan. Di Blumberg 94 Bruce Blumberg menggambarkan mekanisme terperinci untuk pemilihan tindakan kompleks dan dengan Tinsley Galyean di Blumberg 95 membahas desain karakter VR yang mampu melakukan improvisasi dan respons otonom terhadap arah eksternal. Salah satu penerapan karakter ini adalah dalam sistem ALIVE Maes 95 oleh Patties Maes dkk. Sistem Perbaikan oleh Ken Perlin dan Athomas Goldberg Perlin 96 juga mencakup keseluruhan dari pergerakan ke pilihan tindakan, namun menggunakan pendekatan unik berdasarkan skrip perilaku dan perlin146s 1985 sintesis prosedural tekstur Perlin 85 diterapkan pada gerakan. James Cremer dan rekannya telah menciptakan pengemudi otonom untuk bertindak sebagai 147extras148 menciptakan lalu lintas ambient dalam simulator mengemudi mobil interaktif Cremer 96. Robin Green (dari BullfrogEA) telah mengembangkan sistem dewasa untuk karakter otonom yang digunakan di Dungeon Keeper 2 yang diilhami sebagian oleh awal Draft makalah ini Dave Pottinger telah memberikan diskusi rinci tentang kemudi dan koordinasi untuk kelompok karakter dalam permainan Pottinger 1999. Locomotion Locomotion adalah bagian bawah hierarki perilaku tingkat tiga yang dijelaskan di atas. Lapisan penggerak mewakili perwujudan karakter146. Ini mengubah sinyal kontrol dari lapisan kemudi menjadi gerak karakter146s 147body.148 Gerakan ini tunduk pada batasan yang dipaksakan oleh model fisik berbasis tubuh, seperti interaksi momentum dan kekuatan (pembatasan kekuatan yang dapat diterapkan oleh tubuh ). Seperti dijelaskan di atas, kuda koboi14 bisa dianggap sebagai contoh lapisan penggerak. Keputusan kemudi pengendara disampaikan melalui sinyal kontrol sederhana ke kuda yang mengubahnya menjadi gerakan. Inti pembuatan perbedaan abstrak antara kemudi dan penggerak adalah untuk mengantisipasi penggunaan modul penggerak baru. Bayangkan mengangkat pengendara dari kuda dan menempatkannya di motor lintas negara. Pemilihan tujuan dan perilaku kemudi tetap sama. Semua yang telah berubah adalah mekanisme pemetaan sinyal kontrol (berjalan lebih cepat, belok kanan.) Bergerak. Awalnya itu melibatkan pergerakan berkaki (keseimbangan, tulang, otot) dan sekarang melibatkan penggerak beroda (mesin, roda, rem). Peran pengendara tidak berubah. Ini menunjukkan bahwa dengan konvensi yang sesuai untuk mengkomunikasikan sinyal kontrol, perilaku kemudi dapat sepenuhnya terlepas dari skema penggerak spesifik. Meskipun dalam praktiknya perlu dikompensasikan kemampuan dan karakteristik yang berbeda dari sistem penggerak individu. Hal ini dapat dilakukan dengan menyesuaikan parameter tuning untuk skema gerak yang diberikan (yang merupakan pendekatan yang diambil dalam perilaku kemudi yang dijelaskan di bawah ini) atau dengan menggunakan teknik adaptif dan self-calibrating (cara pengemudi manusia dengan cepat menyesuaikan diri dengan karakteristik yang tidak biasa mobil). Dalam kasus pertama, perilaku kemudi dapat menentukannya melalui tuning apriori sehingga kecepatan karakter dalam situasi tertentu harus 23 mph, dalam kasus kedua mungkin dikatakan turun sedikit148 sampai hasil yang sama diperoleh. Penggerak karakter otonom dapat didasarkan pada, atau terlepas dari, penggambaran animasinya. Karakter dapat diwakili oleh simulasi berjalan dinamis yang dinamis secara fisik, memberikan animasi realistis dan gerak perilaku. Atau karakter mungkin memiliki model penggerak yang sangat sederhana (seperti yang dijelaskan pada bagian berikutnya) yang menampilkan gambar statis (katakanlah pesawat ruang angkasa) atau pra-animasi (seperti gambar manusia yang melakukan siklus berjalan). Pendekatan hibrida adalah dengan menggunakan model penggerak sederhana dan model animasi adaptif, seperti siklus gerak terbalik invers-kinematik, untuk menjembatani kesenjangan antara penggerak abstrak dan medan beton. Akhirnya, penggerak dapat dibatasi pada gerakan yang melekat pada rangkaian segmen pra-animasi yang ditetapkan (berjalan, berlari, berhenti, belok kiri.) Yang dipilih secara discretely atau dicampur bersama-sama. Model Kendaraan Sederhana Pendekatan yang diambil dalam makalah ini adalah untuk mempertimbangkan perilaku kemudi pada dasarnya terlepas dari skema gerak yang mendasarinya. Model penggerak sederhana akan disajikan agar pembahasan perilaku kemudi lebih konkret. Model penggerak ini akan didasarkan pada kendaraan ideal sederhana. Pilihan dari istilah 1458 diilhami beberapa derajat oleh Braitenberg 84. Hal ini dimaksudkan untuk mencakup berbagai macam alat angkut, mulai dari alat beroda hingga kuda, dari pesawat terbang hingga kapal selam, dan (walaupun tentu saja meregangkan terminologi) untuk memasukkan penggerak oleh Kaki yang indah. Model kendaraan yang digambarkan di sini sangat sederhana dan generik sehingga merupakan pendekatan yang sama baiknya (atau sama buruknya) dengan semua itu. Model kendaraan ini berdasarkan aproksimasi massa titik. Di satu sisi yang memungkinkan model fisik berbasis sederhana dan sederhana secara komputasi sederhana (misalnya, massa titik memiliki kecepatan (momentum linier) namun tidak ada momen inersia (momentum rotasi)). Di sisi lain, tidak bisa menjadi model fisik yang sangat menarik karena massa titik tidak ada di dunia nyata. Setiap benda fisik dengan massa harus memiliki jari-jari yang tidak nol dan karenanya merupakan momen inersia. Penggunaan model kendaraan non-fisik yang disederhanakan ini hanya untuk kenyamanan dan dimaksudkan untuk tidak kehilangan generalisitas148 Seharusnya selalu memungkinkan untuk mengganti model kendaraan berbasis fisik yang lebih masuk akal dan lebih realistis. Massa titik didefinisikan oleh properti posisi dan properti massa. Selain itu, model kendaraan sederhana mencakup properti kecepatan. Kecepatan dimodifikasi dengan menerapkan kekuatan. Karena ini adalah kendaraan, kekuatan ini pada umumnya berlaku sendiri, dan karenanya terbatas. Sebagai contoh, gaya khas yang menyesuaikan kecepatan kendaraan adalah dorong. Yang dihasilkan oleh pembangkit listrik sendiri, dan karenanya sangat kecil oleh kapasitas pembangkit listrik. Untuk model kendaraan sederhana, gagasan ini dirangkum dengan parameter kekuatan maksimum 147max maksimal (maxforce). Sebagian besar kendaraan ditandai dengan kecepatan tertinggi. Biasanya keterbatasan ini disebabkan oleh interaksi antara akselerasi karena daya dorong dan deselerasi yang rendah karena getaran kental, gesekan, atau (dalam sistem berkaki) momentum bagian reciprocating. Sebagai alternatif untuk simulasi realistis dari semua kekuatan pembatas ini, model kendaraan sederhana mencakup parameter kecepatan maksimal 147max (maxspeed). Batas kecepatan ini ditegakkan dengan pemotongan kinematik vektor kecepatan kendaraan. Akhirnya, model kendaraan sederhana mencakup orientasi. Yang diambil bersama dengan posisi kendaraan146s membentuk ruang koordinat lokal kecepatan-melintas dimana model geometris kendaraan dapat dilampirkan. (Istilah pelokalan dan globalisasi akan digunakan dalam makalah ini untuk berkonotasi mengubah vektor ke dan dari ruang lokal ini.) Untuk model kendaraan 3D, nilai vektor posisi dan kecepatan memiliki tiga komponen dan nilai orientasi adalah himpunan tiga vektor. (Atau matriks 3x3, atau quaternion). Untuk kendaraan 2D, vektor masing-masing memiliki dua komponen, dan nilai orientasi dua vektor 2D atau dapat digambarkan sebagai sudut heading skalar tunggal. Fisika model kendaraan sederhana didasarkan pada integrasi Euler ke depan. Pada setiap tahap simulasi, kekuatan kemudi yang ditentukan secara taktis (dibatasi oleh maxforce) diterapkan pada massa titik kendaraan146. Ini menghasilkan percepatan yang sama dengan kekuatan kemudi dibagi dengan massa kendaraan. Akselerasi itu ditambahkan ke kecepatan lama untuk menghasilkan kecepatan baru, yang kemudian dipotong oleh kecepatan maksimal. Akhirnya, kecepatan ditambahkan ke posisi lama: Model kendaraan sederhana mempertahankan ruang lokal kecepatan-selaras dengan penyesuaian bertahap dari langkah waktu sebelumnya. Sistem koordinat lokal didefinisikan dalam empat vektor: vektor posisi yang menentukan asal lokal, dan tiga vektor arah yang berfungsi sebagai basis vektor dari ruang. Vektor dasar menunjukkan arah dan panjang satuan koordinat pada masing-masing tiga arah yang saling tegak lurus terhadap kendaraan. Sumbu ini akan disebut di sini sebagai forward. Up. Dan sisi. (Ini sesuai, tentu saja, dengan sumbu X. Y dan Z dari R 3. Tapi beberapa orang berpikir jelas Y sementara beberapa orang berpikir itu jelas Z. Istilah deskriptif akan digunakan menggantikan nama Cartesian untuk kejelasan.) Agar tetap selaras dengan kecepatan pada setiap langkah waktu, basis vektor harus diputar ke arah yang baru. (Jika kecepatan nol orientasi lama dipertahankan.) Alih-alih menggunakan rotasi eksplisit, ruang lokal direkonstruksi menggunakan kombinasi substitusi, aproksimasi, dan reortogonalisasi. Kita mulai dengan kecepatan baru dan pendekatan ke arah atas yang baru. Misalnya, arah lama bisa digunakan sebagai perkiraan ke atas. Kami menggunakan operasi silang produk vektor untuk membangun basis vektor baru: Gagasan dasarnya adalah perkiraan mendekati hampir tegak lurus terhadap arah maju yang baru, karena perubahan orientasi frame-to-frame biasanya kecil. Arah sisi baru akan tegak lurus terhadap forward baru. Dari definisi cross product. Yang baru adalah produk silang dari sisi maju dan samping yang tegak lurus dan begitu tegak lurus terhadap masing-masing. Konsep penyelarasan kecepatan148 tidak secara unik menentukan orientasi. Tingkat kebebasan yang sesuai dengan rotasi di sekitar sumbu depan (juga dikenal sebagai gulungan) tetap tidak dibatasi. Membangun ruang lokal baru relatif terhadap yang sebelumnya (dengan, misalnya, menggunakan arah lama sebagai pendekatan awal yang baru) akan memastikan bahwa orientasi gulungan setidaknya tetap konsisten. Mendefinisikan nilai revolving1488 roll memerlukan heuristik lebih lanjut, berdasarkan pada penggunaan model kendaraan yang diinginkan. Untuk kendaraan 147 (seperti pesawat terbang, pesawat ruang angkasa, dan kapal selam), berguna untuk mendefinisikan roll dalam hal perbankan. Ide dasar perbankan adalah menyelaraskan kendaraan bermotor (- up axis) dengan gravitasi yang nyata karena gaya sentrifugal selama belokan. Sebaliknya kita menginginkan arah ke atas agar sejajar dengan gaya sentripetal yang menghasilkan manuver. Dengan adanya gravitasi, arah bawah harus sejajar dengan jumlah percepatan percepatan dan percepatan gravitasi. Kami juga ingin menambahkan orientasi saat ini untuk meredam perubahan mendadak dalam gulungan. Jadi untuk menerapkan perbankan dalam model kendaraan sederhana, perkiraan arah ke depan adalah jumlah tertimbang: percepatan kemudi, percepatan gravitasi, dan lama. Untuk kendaraan peluncur, meluncur, atau berkaki belakang, kami ingin membatasi posisi kendaraan ke permukaan dan menyelaraskan poros kendaraan ke permukaan normal. Selain itu kecepatan harus dibatasi menjadi tangensial murni ke permukaan. Persyaratan ini dapat dengan mudah dipenuhi jika manifold permukaan diwakili sedemikian rupa sehingga titik sewenang-wenang di ruang angkasa (sesuai dengan posisi kendaraan lama) dapat dipetakan ke: (1) titik terdekat di permukaan, dan (2) Permukaan normal pada saat itu. Kecepatan dapat dibuat bersinggungan dengan mengurangkan bagian normal ke permukaan. Posisi kendaraan dilekatkan pada titik di permukaan, dan permukaannya normal menjadi porosnya. Dalam model kendaraan sederhana ini, sinyal kontrol yang dilewatkan dari perilaku kemudi ke perilaku penggerak terdiri dari satu kuantitas vektor: gaya kemudi yang diinginkan. Model kendaraan yang lebih realistis akan memiliki rangkaian sinyal kontrol yang sangat berbeda. Misalnya mobil memiliki setir, akselerator dan rem yang masing-masing bisa diwakili sebagai jumlah skalar. Ada kemungkinan untuk memetakan vektor gaya kemudi umum ke dalam sinyal skalar ini: komponen samping vektor kemudi dapat diartikan sebagai sinyal kemudi, komponen depan vektor kemudi dapat dipetakan ke dalam sinyal akselerator jika positif, atau ke dalam Sinyal rem jika negatif. Pemetaan ini bisa asimetris, misalnya mobil biasa bisa melambat karena pengeremannya jauh lebih cepat daripada yang bisa diakselerasikan karena dorong mesin, seperti yang ditunjukkan pada Gambar 2. Gambar 2: Gaya kemudi asimetris Karena asumsi pelurusan kecepatan, kendaraan sederhana ini. Model tidak dapat mensimulasikan efek seperti tergelincir, berputar atau meluncur. Selanjutnya model ini memungkinkan kendaraan berputar saat kecepatannya nol. Sebagian besar kendaraan nyata tidak dapat melakukan ini (keduanya terlepas dari holistik148) dan bagaimanapun juga, hal itu memungkinkan perubahan orientasi yang tidak diinginkan selama satu waktu saja. Masalah ini dapat diatasi dengan menempatkan batasan tambahan pada perubahan orientasi, atau dengan membatasi komponen kemudi lateral pada kecepatan rendah, atau dengan mensimulasikan momen inersia. Perilaku Pengarah Diskusi tentang perilaku kemudi spesifik ini mengasumsikan bahwa penggerak diimplementasikan dengan model kendaraan sederhana yang dijelaskan di atas, dan diberi parameter oleh satu vektor gaya kemudi tunggal. Oleh karena itu, perilaku kemudi digambarkan dalam perhitungan geometrik vektor yang mewakili gaya kemudi yang diinginkan. Perhatikan bahwa umumnya besarnya vektor kemudi ini tidak relevan, karena biasanya akan dipangkas menjadi maksimal oleh model kendaraan. Perhatikan juga bahwa banyak dari panggilan ke panjang dan fungsi normalisasi dalam formulasi ini dapat digantikan oleh rutinitas cepat yang menggunakan perkiraan panjang seperti pada Ohashi 94. Istilah 147we148 atau 147our148 kadang-kadang digunakan untuk menunjukkan perspektif orang pertama dari karakter. Didorong oleh perilaku tertentu. Diagram animasi yang menggambarkan perilaku ini dapat ditemukan di web di Redcwrsteer Seek (atau mengejar target statis) bertindak untuk mengarahkan karakter ke arah posisi tertentu di ruang global. Perilaku ini menyesuaikan karakter sehingga kecepatannya secara radial sesuai dengan target. Perhatikan bahwa ini berbeda dengan gaya yang menarik (seperti gravitasi) yang akan menghasilkan jalur orbital di sekitar titik target. Kecepatan 14714 adalah vektor ke arah dari karakter ke sasaran. Panjang velocity148 bisa jadi kecepatan maksimal. Atau bisa jadi kecepatan karakter146 saat ini, tergantung pada aplikasi tertentu. Vektor kemudi adalah perbedaan antara kecepatan yang diinginkan dan kecepatan arus karakter146 saat ini, lihat Gambar 3. Jika karakter terus dicari. Akhirnya akan melewati target, dan kemudian kembali mendekati lagi. Ini menghasilkan gerakan sedikit seperti ngengat yang berdengung di sekitar bola lampu. Bandingkan ini dengan deskripsi kedatangan di bawah ini. Flee hanyalah kebalikan dari mencari dan bertindak untuk mengarahkan karakter sehingga kecepatannya secara radial selaras jauh dari target. Titik kecepatan yang diinginkan ke arah yang berlawanan. Gambar 4: Pengejaran dan Pengejaran Pengejaran serupa dengan pencarian kecuali bahwa penggalian (target) adalah karakter bergerak lainnya. Pengejaran yang efektif membutuhkan prediksi posisi masa depan target146. Pendekatan yang diambil di sini adalah dengan menggunakan alat prediksi sederhana dan untuk mengevaluasi kembali setiap langkah simulasi. Sebagai contoh, prediktor berbasis kecepatan linier sesuai dengan asumsi bahwa penggalian tidak akan berubah selama interval prediksi. Meskipun asumsi ini sering salah, prediksi yang dihasilkan hanya akan digunakan sekitar 130 detik. Posisi karakter T unit waktu di masa depan (dengan asumsi tidak manuver) dapat diperoleh dengan mengukur kecepatannya dengan T dan menambahkan bahwa offset ke posisi saat ini. Pengarah untuk pengejaran kemudian hanya hasil penerapan perilaku mengarahkan kemudi ke lokasi target yang diprediksi. Lihat Gambar 4. Kunci penerapan pengejaran ini adalah metode yang digunakan untuk memperkirakan interval prediksi T. Idealnya, T adalah waktu sampai intersepsi, namun nilainya tidak dapat diketahui karena tambang dapat melakukan manuver yang sewenang-wenang dan tidak dapat diprediksi. T dapat diasumsikan sebagai konstanta, yang naif, akan menghasilkan usaha yang lebih baik daripada pencarian sederhana (yang sesuai dengan T0). Namun untuk performa yang wajar T harus lebih besar saat pengejarnya jauh dari buruan, dan kecil saat berada di dekatnya. Pengukur sederhana dengan kualitas sedang adalah TDc dimana D adalah jarak antara pengejar dan penggali, dan c adalah parameter balik. Pengukur yang lebih canggih dapat diperoleh dengan memperhatikan judul pengejar dan penggali relatif, dan apakah pengejar umumnya berada di depan, di belakang, atau ke samping, buruan. Kedua metrik ini dapat dinyatakan dalam istilah produk dot sederhana (antara vektor unit ke depan, dan antara quarry146s maju dan offset ke posisi pengejaran146). Perhatikan bahwa perawatan harus dilakukan untuk mengurangi T (misalnya ke nol) saat pengejar menemukan dirinya sejajar dengan, dan di depan, buruannya. Another approach to both seek and pursuit is based on the fact that when our character is on a collision course with a target, it will appear at a constant heading in our character146s local space. Conversely our character can steer toward interception by contriving to keep the target at a constant heading. Evasion is analogous to pursuit . except that flee is used to steer away from the predicted future position of the target character. Optimal techniques for pursuit and evasion exist in the field of control theory Isaacs 65. The versions given here are in tended to be lightweight and are nonoptimal. In natural systems, evasion is often 147intentionally148 nonoptimal in order to be unpredictable, allowing it to foil predictive pursuit strategies, see Cliff 96. Figure 5: offset pursuit Offset pursuit refers to steering a path which passes near, but not directly into a moving target. Examples would be a spacecraft doing a 147fly-by148 or an aircraft doing a 147strafing run148: flying near enough to be within sensor or weapon range without colliding with the target. The basic idea is to dynamically compute a target point which is offset by a given radius R from the predicted future position of the quarry, and to then use seek behavior to approach that offset point, see Figure 5. To construct the offset point: localize the predicted target location (into our character146s local coordinate space) project the local target onto the character146s side-up plane, normalize that lateral offset, scale it by - R, add it to the local target point, and globalize that value. Arrival behavior is identical to seek while the character is far from its target. But instead of moving through the target at full speed, this behavior causes the character to slow down as it approaches the target, eventually slowing to a stop coincident with the target, as shown in Figure 6. The distance at which slowing begins is a parameter of the behavior. This implementation is similar to seek . a desired velocity is determined pointing from the character towards the target. Outside the stopping radius this desired velocity is clipped to maxspeed . inside the stopping radius, desired velocity is ramped down (e. g. linearly) to zero. Real world examples of this behavior include a baseball player running to, and then stopping at a base or an automobile driving towards an intersection and coming to a stop at a traffic light. Figure 7: obstacle avoidance Obstacle avoidance behavior gives a character the ability to maneuver in a cluttered environment by dodging around obstacles. There is an important distinction between obstacle avoidance and flee behavior. Flee will always cause a character to steer away from a given location, whereas obstacle avoidance takes action only when a nearby obstacle lies directly in front of the character. For example, if a car was driving parallel to a wall, obstacle avoidance would take no corrective steering action, but flee would attempt to turn away from the wall, eventually driving perpendicular to it. The implementation of obstacle avoidance behavior described here will make a simplifying assumption that both the character and obstacle can be reasonably approximated as spheres, although the basic concept can be easily extend to more precise shape models. Keep in mind that this relates to obstacle avoidance not necessarily to collision detection . Imagine an airplane trying to avoid a mountain. Neither are spherical in shape, but it would suffice that the plane146s bounding sphere avoids the mountain146s bounding sphere. A decomposable hierarchy of bounding spheres can be used for efficient representation of shapes for collision detection Hubbard 96, and presumably for obstacle avoidance too. An unrelated obstacle avoidance technique is described in Egbert 96. The geometrical construction of obstacle avoidance behavior bares some similarity to the offset pursuit behavior described above. It is convenient to consider the geometrical situation from the character146s local coordinate system. The goal of the behavior is to keep an imaginary cylinder of free space in front of the character. The cylinder lies along the character146s forward axis, has a diameter equal to the character146s bounding sphere, and extends from the character146s center for a distance based on the character146s speed and agility. An obstacle further than this distance away is not an immediate threat. The obstacle avoidance behavior considers each obstacle in turn (perhaps using a spatial portioning scheme to cull out distance obstacles) and determines if they intersect with the cylinder. By localizing the center of each spherical obstacle, the test for non-intersection with the cylinder is very fast. The local obstacle center is projected onto the side-up plane (by setting its forward coordinate to zero) if the 2D distance from that point to the local origin is greater than the sum of the radii of the obstacle and the character, then there is no potential collision. Similarly obstacles which are fully behind the character, or fully ahead of the cylinder, can be quickly rejected. For any remaining obstacles a line-sphere intersection calculation is performed. The obstacle which intersects the forward axis nearest the character is selected as the 147most threatening.148 Steering to avoid this obstacle is computed by negating the (lateral) side-up projection of the obstacle146s center. In Figure 7 obstacle A does not intersect the cylinder, obstacles B and C do, B is selected for avoidance, and corrective steering is to the character146s left. The value returned from obstacle avoidance is either (a) the steering value to avoid the most threatening obstacle, or (b) if no collision is imminent, a special value (a null value, or the zero vector) to indicate that no corrective steering is required at this moment. A final note regarding interaction of obstacle avoidance and goal seeking. Generally we only care about obstacles which are between us and our goal. The mountain beyond the airport is ignored by the airplane, but the mountain between the plane and the airport is very important. Wander is a type of random steering. One easy implementation would be to generate a random steering force each frame, but this produces rather uninteresting motion. It is 147twitchy148 and produces no sustained turns. A more interesting approach is to retain steering direction state and make small random displacements to it each frame. Thus at one frame the character may be turning up and to the right, and on the next frame will still be turning in almost the same direction. The steering force takes a 147random walk148 from one direction to another. This idea can be implemented several ways, but one that has produced good results is to constrain the steering force to the surface of a sphere located slightly ahead of the character. To produce the steering force for the next frame: a random displacement is added to the previous value, and the sum is constrained again to the sphere146s surface. The sphere146s radius (the large circle in Figure 8) determines the maximum wandering 147strength148 and the magnitude of the random displacement (the small circle in Figure 8) determines the wander 147rate.148 Another way to implement wander would be to use coherent Perlin noise Perlin 85 to generate the steering direction. Related to wander is explore (where the goal is to exhaustively cover a region of space) and forage (combining wandering with resource seeking). See Beer 90 and Tu 96 for more details. Figure 9: path following Path following behavior enables a character to steer along a predetermined path, such as a roadway, corridor or tunnel. This is distinct from constraining a vehicle rigidly to a path like a train rolling along a track. Rather path following behavior is intended to produce motion such as people moving down a corridor: the individual paths remain near, and often parallel to, the centerline of the corridor, but are free to deviate from it. In the implementation described here, a path will be idealized as a spine and a radius . The spine might be represented as a spline curve or a 147poly-line148 (a series of connected line segments). The path is then a 147tube148 or 147generalized cylinder:148 a circle of the specified radius, swept along the specified spine. The goal of the path following steering behavior is to move a character along the path while staying within the specified radius of the spine. If the character is initially far away from the path, it must first approach, then follow the path. To compute steering for path following . a velocity-based prediction is made of the character146s future position, as discussed above in regard to obstacle avoidance behavior. The predicted future position is projected onto the nearest point on the path spine. See Figure 9. If this projection distance (from the predicted position to the nearest on-path point) is less than the path radius, then the character is deemed to be correctly following the path and no corrective steering is required. Otherwise the character is veering away from the path, or is too far away from the path. To steer back towards the path, the seek behavior is used to steer towards the on-path projection of the predicted future position. Like in obstacle avoidance . a null or zero value is returned is returned if no corrective steering is required. A path can be followed without regard to direction, or in a specified direction (from A to B or from B to A) by adjusting the target point along the path in the desired direction. Figure 10: wall following and containment Variations on path following include wall following and containment as shown in Figure 10. Wall following means to approach a 147wall148 (or other surface or path) and then to maintain a certain offset from it Beer 90. For a discussion of offset goals, see offset pursuit above. Containment refers to motion which is restricted to remain within a certain region. Path following is a type of containment where the allowable region is a cylinder around the path146s spine. Examples of containment include: fish swimming in an aquarium and hockey players skating within an ice rink. To implement: first predict our character146s future position, if it is inside the allowed region no corrective steering is necessary. Otherwise we steer towards the allowed region. This can be accomplished by using seek with an inside point (for example, we can project the future position to the obstacle surface, and then extend this offset to obtain a target point) or we can determine the intersection of our path with the boundary, find the surface normal at that point, and then use the component of the surface normal which is perpendicular to our forward direction as the corrective lateral steering. Figure 11: flow field following Flow field following steering behavior provides a useful tool for directing the motion of characters based on their position within an environment. It is particularly valuable in some production teams because it allows motion specification to be made without use of programming and so can used by the art staff directly. In the case of game production this person might be a 147level designer148 and in animation production they might be a 147scene planner148 or 147layout artist.148 In flow field following behavior the character steers to align its motion with the local tangent of a flow field (also known as a force field or a vector field ). The flow field defines a mapping from a location in space to a flow vector: imagine for example a floor with arrows painted on it. Such a map, typically representing the floor plan of an environment, can be easily created by an artist with a special purpose 147paint148 program which allows them to draw the desired traffic flow with a paint brush. The implementation of flow field following is very simple. The future position of a character is estimated and the flow field is sampled at that location. This flow direction (vector F in Figure 11) is the 147desired velocity148 and the steering direction (vector S) is simply the difference between the current velocity (vector V) and the desired velocity. Figure 12: unaligned collision avoidance Unaligned collision avoidance behavior tries to keep characters which are moving in arbitrary directions from running into each other. Consider your own experience of walking across a plaza or lobby full of other walking people: avoiding collisions involves predicting potential collisions and altering your direction and speed to prevent them. If all nearby characters are aligned . a less complicated strategy can be used, see separation below. To implement this as a steering behavior, our character considers each of the other characters and determines (based on current velocities) when and where the two will make their nearest approach . A potential for collision exists if the nearest approach is in the future, and if the distance between the characters at nearest approach is small enough (indicated by circles in Figure 12). The nearest of these potential collisions, if any, is determined. The character then steers to avoid the site of the predicted collision. It will steer laterally to turn away from the potential collision. It will also accelerate forward or decelerate backwards to get to the indicate site before or after the predicted collision. In Figure 12 the character approaching from the right decides to slow down and turn to the left, while the other character will speed up and turn to the left. Figure 13: neighborhood The next three steering behaviors: separation . cohesion . and alignment . relate to groups of characters. In each case, the steering behavior determines how a character reacts to other characters in its local neighborhood . Characters outside of the local neighborhood are ignored. As shown in Figure 13, the neighborhood is specified by a distance which defines when two characters are 147nearby148, and an angle which defines the character146s perceptual 147field of view.148 Figure 14: separation Separation steering behavior gives a character the ability to maintain a certain separation distance from others nearby. This can be used to prevent characters from crowding together. To compute steering for separation . first a search is made to find other characters within the specified neighborhood. This might be an exhaustive search of all characters in the simulated world, or might use some sort of spatial partitioning or caching scheme to limit the search to local characters. For each nearby character, a repulsive force is computed by subtracting the positions of our character and the nearby character, normalizing, and then applying a 1r weighting. (That is, the position offset vector is scaled by 1r 2 .) Note that 1r is just a setting that has worked well, not a fundamental value. These repulsive forces for each nearby character are summed together to produce the overall steering force. See Figure 14. Figure 15: cohesion Cohesion steering behavior gives an character the ability to cohere with (approach and form a group with) other nearby characters. See Figure 15. Steering for cohesion can be computed by finding all characters in the local neighborhood (as described above for separation ), computing the 147average position148 (or 147center of gravity148) of the nearby characters. The steering force can applied in the direction of that 147average position148 (subtracting our character position from the average position, as in the original boids model), or it can be used as the target for seek steering behavior. Figure 16: alignment Alignment steering behavior gives an character the ability to align itself with (that is, head in the same direction andor speed as) other nearby characters, as shown in Figure 16. Steering for alignment can be computed by finding all characters in the local neighborhood (as described above for separation ), averaging together the velocity (or alternately, the unit forward vector) of the nearby characters. This average is the 147desired velocity,148 and so the steering vector is the difference between the average and our character146s current velocity (or alternately, its unit forward vector). This steering will tend to turn our character so it is aligned with its neighbors. Flocking behavior: in addition to other applications, the separation . cohesion and alignment behaviors can be combined to produce the boids model of flocks, herds and schools Reynolds 87 (see also Tu 94, Tu 96 and Hodgins 94). In some applications it is sufficient to simply sum up the three steering force vectors to produce a single combined steering for flocking (see Combining Behaviors below). However for better control it is helpful to first normalize the three steering components, and then to scale them by three weighting factors before summing them. As a result, boid flocking behavior is specified by nine numerical parameters: a weight (for combining), a distance and an angle (to define the neighborhood, see Figure 13) for each of the three component behaviors. Figure 17: leader following Leader following behavior causes one or more character to follow another moving character designated as the leader . Generally the followers want to stay near the leader, without crowding the leader, and taking care to stay out of the leader146s way (in case they happen to find them selves in front of the leader). In addition, if there is more than one follower, they want to avoid bumping each other. The implementation of leader following relies on arrival behavior (see above) a desire to move towards a point, slowing as it draws near. The arrival target is a point offset slightly behind the leader. (The offset distance might optionally increases with speed.) If a follower finds itself in a rectangular region in front of the leader, it will steer laterally away from the leader146s path before resuming arrival behavior. In addition the followers use separation behavior to prevent crowding each other. See Figure 17. Finally, here are quick sketches of some other steering behaviors that fit into the same general category as those described in more detail above. Interpose steering behavior attempts to put its character between two other moving characters, for example a soccer player trying to block a pass between two members of the opposing team. The general approach is similar to pursuit described above: predict the future position of the two other characters, determine a target point by interpolating between the future positions, and use seek to steer toward the target point. Related to leader following and pursuit . we could shadow our quarry by approaching and then using alignment to match their speed and heading. The arrival behavior described above can be considered a constraint on position and speed. This can be extended to simultaneously constrain orientation (to produce docking ), or a non-zero velocity, andor to meet these constraints at a given time. Hide behavior involves identifying a target location which is on the opposite side of an obstacle from the opponent, and steering toward it using seek . Combining Behaviors The individual steering behaviors described above serve as building blocks for more complex patterns of behavior. They are components of a larger structure, like notes of a melody or words of a story. In order to make interesting and life-like behaviors we need to select among, and blend between, these individual components. Unless an autonomous character exists in an very simple world, it would seldom make sense for the character to continually execute a single steering behavior. Combining behaviors can happen in two ways. A character may sequentially switch between behavioral modes as circumstances change in its world. For example, imagine caribou grazing in a meadow when suddenly they sense wolves approaching. This event triggers a discrete behavioral switch. All thoughts of grazing are forgotten as the caribou herd turns to flee from the predators. There is no tendency to mix these behaviors: a caribou will not slow down while running from a wolf in order to grab another bite of food. These discrete changes of behavioral state take place at the action selection level, the top of the three level behavioral hierarchy discussed in the Introduction. There is a extensive discussion of action selection in Tu 94, Tu 96 and in Blumberg 94. On the other hand, some kinds of behaviors are commonly blended together, effectively acting in parallel. For example, as the caribou flee through the forest, they blend evasion and obstacle avoidance together to allow them to escape from the wolves while dodging trees. A caribou cannot afford to ignore either component behavior, it must always be moving in a direction that both takes it away from the wolf and avoids collisions with trees. This behavioral blending occurs at the middle steering level of the behavioral hierarchy. Blending of steering behaviors can be accomplished in several ways. The most straightforward is simply to compute each of the component steering behaviors and sum them together, possibly with a weighting factor for each of them. (Note that steering vectors are especially easy to blend, other kinds of behaviors, producing other kinds of values (e. g. conversational behaviors) could be much harder to combine.) This simple linear combination often works well, but has at least two shortcomings: it is not the most computationally efficient approach, and despite adjusting the weights, component behaviors may cancel each other out at inopportune times. The computation load can be decreased by observing that a character146s momentum serves to apply a low-pass filter to changes in steering force. So rather than compute several steering components each simulation step and average them together, we could instead select one steering component to compute and apply each frame, and depend on momentum (and perhaps some explicit damping of acceleration) to blend them together. The problem of components canceling each other out can be addressed by assigning a priority to components. (For example: first priority is obstacle avoidance . second is evasion . ) The steering controller first checks to see if obstacle avoidance returns a non-zero value (indicating a potential collision), if so it uses that. Otherwise, it moves on to the second priority behavior, and so on. A hybrid of these techniques that the author has found useful is 147prioritized dithering148: with a certain probability the first priority behavior is evaluated, and if it returns a non-zero (non-null) value that will be used. Otherwise (if the behavior returns zero, or it was skipped over due to the random selection) the second priority behavior is considered, and so on. In Reynolds 87 a blending scheme called 147prioritized acceleration allocation148 was used with the boids flocking model. The basic idea was that by adjusting their magnitude, higher priority behaviors could decide whether or not to leave any steering force for use by lower priority behaviors. In the course of several reimplementations of boids over the years, a simple linear combination of the component behaviors has proved sufficient. When combining flocking with other behaviors such as obstacle avoidance, both simple summing and prioritized dither have been used successfully. Conclusions This paper defined 147autonomous character148 in terms of autonomous agents and improvisational action. It presented a decomposition of the task of constructing motion behaviors for autonomous characters into a three level hierarchy of: action selection, steering, and locomotion. It has defined a minimal implementation of the locomotion level in terms of a 147simple vehicle model.148 It has then presented a collection of simple, common steering behaviors. (Including: seek . flee . pursuit . evasion . offset pursuit . arrival . obstacle avoidance . wander . path following . wall following . containment . flow field following, unaligned collision avoidance . separation . cohesion . alignment . flocking . and leader following .) Finally it has described some techniques for blending these simple steering behaviors together. Acknowledgments The techniques described in this paper have been developed over the last twelve years, for many different projects, at several companies. I wish to acknowledge the helpful cooperation of all the companies and coworkers involved. Specifically I wish to thank the following people for managerial support and technical collaboration. At Sony Computer Entertainment America: Phil Harrison, John Phua, Attila Vass, Gabor Nagy, Sky Chang, and Tom Harper. At DreamWorks Feature Animation: Dylan Kohler, Bart Gawboy, Matt Arrott, Lance Williams, Saty Raghavachary, and Mike Ullner. At SGI146s Silicon Studio: Bob Brown, Leo Blume, Roy Hashimoto, and especially my behavioral animation colleague Xiaoyuan Tu. At Electronic Arts: Luc Barthelet, Steve Crane, Kelly Pope, Steve Sims, and Frank Giraffe. At Symbolics Graphics Division: Tom McMahon, Andy Kopra, Larry Malone, and Michael Wahrman. Finally, loving thanks to my wife Lisa and our children Eric and Dana. Before they become fully autonomous, I hope I steer the kids in the right direction. Certainly they are already real characters . 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Sims, Karl (1994) 147Evolving Virtual Creatures148, Proceedings of SIGGRAPH 94, Computer Graphics Proceedings, Annual Conference Series, Andrew Glassner editor, ACM SIGGRAPH, ISBN 0-89791-667-0, pages 15-22. biota. orgksimsblockiesindex. html. ftp:ftp. de. uupubresearchciAlifekarl-sims Still, G Keith (1994) 147Simulating Egress using Virtual Reality - a Perspective View of Simulation and Design148, IMAS Fire Safety on Ships. Strassmann, Steve (1991) Desktop Theater: Automatic Generation of Expressive Animation, PhD thesis, MIT Media Lab. methodstrazstraz-phd. pdf Thalmann, Daniel Renault, Olivier and Magnenat-Thalmann Nadia (1990) 147A Vision-Based Approach to Behavioral Animation148, Journal of Visualization and Computer Animation, John Wiley amp Sons, 1(1) pages 18-21. 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Fiume, E. and Vranesic, Z. G. (1990) quotReusable Motion Synthesis Using State-Space Controllersquot, Proceedings of SIGGRAPH 90, In Computer Graphics Proceedings, ACM SIGGRAPH, pages 225-234. See dgp. toronto. edupeoplevanpapers. html Grey-Walter, W. (1953) The Living Brain. Gerald Duckworth and Co. Ltd. Wiener, Norbert (1948) Cybernetics, or control and communication in the animal and the machine. Cambridge, Massachusetts: The Technology Press New York: John Wiley amp Sons, Inc. Wilhelms, Jane and Skinner, Robert (1990) A 147Notion148 for Interactive Behavioral Animation Control, IEEE Computer Graphics and Applications, 10(3), pages 14-22. Zapata, R. Lepinay, P. Novales, C. and Deplanques, P. (1992) 147Reactive Behaviors of Fast Mobile Robots in Unstructured Environments: Sensor-Based Control and Neural Networks148 in From Animals to Animats 2: Proceedings of the Second International Conference on Simulation of Adaptive Behavior (SAB92), Meyer, Roitblat and Wilson editors, MIT Press, Cambridge, Massachusetts, pages 108-115 Zeltzer, David (1983) Knowledge-Based Animation, Proceedings SIGGRAPHSIGART Workshop on Motion, pages 187-192. Zeltzer, David (1990) 147Task Level Graphical Simulation: Abstraction, Representation and Control,148 in Making Them Move: Mechanics, Control and Animation of Articulated Figures, N. Badler, B. Barsky and D. Zeltzer, editors. Morgan Kaufmann Publishers. January 14, 1997Integrated Amplifiers amp Receivers Audio Research VSi60: 5000 10025 In the 50Wpc VSi60, a passive line stage is combined with a JFET input stage driving one 6H30 driver tube per channel. Each channels output stage has a matched pair of Svetlana 6550C push-pull tubes with a combination of pentode operation and ARCs partially cathode-coupled topology. Convenient to use, the VSi60 provides output taps at 4 and 8 ohms, as well as four pairs of voltmeter test points. Though it lacked the ultimate control of more powerful amplifiers, the VSi60 combined a glorious midrange with clean, detailed high frequencies and outstanding low-level dynamic articulation. In the VSi60, Audio Research has produced an integrated amplifier of staggering quality, versatility, and value, said BJR. Add 300 for tube cage. (Vol.33 No.9 WWW) Ayre Acoustics AX-5: 9950 Ayres statement integrated amplifier measures 17.25 W by 5 H by 18.75 D, weighs 46 lbs, and has a brushed-aluminum chassis with four balanced and two single-ended inputs. It uses a variable-gain transconductance circuit trickled down from Ayres top-of-the-line KX-R preamp, a class-AB diamond-circuit output section, and delivers 125Wpc into 8 ohms. The AX-5 offered a combination of incisive detail, perfect musical timing and momentum, and naturally warm timbral colors, said AD. Its one of the three best, most musical, most human-sounding solid-state amps Ive ever heard, he concluded. Its wide bandwidth and low distortion are a testament to the intrinsic linearity of the diamond circuit, added JA. In his Follow-Up, Jim Austin expressed admiration for the Ayres minimalist aesthetic, but had no love for its user interface or loudspeaker connectors151and, as did AD in his full review, criticized the noise made by its volume control. Yet he thought the AX-5 sounded superb: immediate and full, with much (but not all) of the richness, texture, and corporeality I associate with a good tube amp. About to be replaced by 20th Anniversary edition. (Vol.36 No.8, Vol.37 No.10 WWW) Ayre Acoustics AX-7e: 3500 10025 The success of this 60Wpc, solid-state, two-channel, fully balanced, integrated amplifier depended on the associated sources. Used from balanced output to balanced input, It was brilliant. Amazing. Stirring, even, said AD. However, used as an unbalanced amp, The AX-7 still sounded good, but its musical performance lacked momentum and, ultimately, excitement. Overall, the Ayre was colorful, clear, well-textured, and spatially convincing. It seemed sensitive to the type and length of speaker cable AD used, and seemed more sensitive to AC power quality than average. I strongly recommend the Ayre AX-7 for use only in an all-balanced system. The 7es power supply now includes greater filtering of the AC mains, increased peak current delivery, and filtering of the rectifier switching noise. In addition, the AX-7es gain stages now use two-stage voltage regulators in place of the earlier versions single-stage regulators. The sound now combined classic Brit-style pacing and tunefulness with near-SET levels of presence and a fine sense of musical flow, a combination that allowed AD to become emotionally involved in the music. The AX-7e is the best integrated Ive ever heard, endorsed WP. One heck of an involving amplifier, he summed up. Compared to the Luxman MQ-88 power amplifier, the Ayre offered greater bass extension and soundstage control but lacked the Luxmans beguiling midrange, said JM. Original AX-7s can be fully upgraded for 250150350, depending on the age of the unit. (Vol.26 No.10 AX-7 Vol.29 No.1, Vol.31 No.3, AX-7e WWW see also The Fifth Element in Vol.34 No.2 and Vol.35 No.4 WWW) Bel Canto C7R: 2595 Made in the US, the versatile C7R is a 60Wpc solid-state FM receiver with four SPDIF digital inputs (two coaxial, two TosLink), two pairs of analog inputs (one phono, one line), one pair of line-level analog outputs, a front-panel headphone jack, and a built-in DAC with USB input capable of handling resolutions up to 24-bit96kHz. Though it lacked some midrange clarity and high-frequency smoothness, the C7R sounded clear, immediate, and powerful, with excellent dynamics and tight, tuneful bass, said EL. I loved the Bel Canto C7R. I recommend it to anyone who wants simplicity and great sound, he concluded. Overall, the C7R is a well-designed piece of hardware, said JA. (Vol.36 No.3 WWW) Jadis I-35: 7995 Made in France, the beautiful I-35 is a tubed, integrated amplifier with five line-level inputs. Though rated to deliver 35Wpc into 115016 ohms, the I-35 produced just 17W into 8 ohms at 1 THD. It uses five small-signal tubes (three 12AU7s and a pair of 12AX7s) and two pairs of KT120 output tubes run in autobias mode in an Ultralinear circuit, with plates and screen grids for each channel tied to the split-coil primaries of transformers expertly designed and made in-house. Build quality and cosmetics were outstanding, inside and out. Though it lacked the fullness and richness of Arts Shindo separates, the Jadis produced a natural and engaging overall sound, with an excellent sense of momentum and a very good sense of the spatial relationships between different sounds in a stereo recording, said AD. This is a damn good amp for getting to the essence of music, he concluded. (Vol.37 No.1 WWW) Kondo Overture: 33,900 Made in Japan, the 32Wpc Overture uses a class-A, Ultralinear output circuit with minimal (3dB) global feedback, executed with split-primary output transformers custom-wound by Tango. It uses two Electro-Harmonix EL34 output pentodes, one 6072, and one 12BH7 per channel. Build quality was exceptional and marked by silver wiring, handmade capacitors, bespoke resistors, a solid-copper ground plane, and a tuned chassis made from a combination of steel, brass, and aluminum. The Overture has no balance control, remote control, mono switch, headphone amplifier, or phono stage, but does provide four pairs of line-level inputs and a choice of 4- or 8-ohm output sockets. Though it was slightly lean and not quite as colorful as ADs Shindo separates, the Overture produced a natural, compelling overall sound with a well-extended treble and exceptional senses of drive and scale. (Vol.36 No.11 WWW) Leben CS300: 3395 10025 With its wood side panels, gold-toned faceplate, and large balance and bass-boost knobs, the line-only CS300 has a decidedly old-fashioned look and feel. It uses two pairs of EL84 power pentode tubes running in class-AB mode to deliver 12Wpc. A rear-panel output control allows the user to switch between transformer secondaries that are optimized for use with speakers with impedances of 4, 6, or 8 ohms. Construction quality was superb throughout. Though it lacked the color, presence, internote silence, and sense of flow of ADs Shindo separates, the Leben distinguished itself as a punchy and realistically textured amp with an especially deep, tight bottom end. It measured about as well as can be expected from its retro design, commented JA. (Vol.34 No.11 WWW) LFD NCSE: 6795 A bigger and more powerful version of LFDs excellent Mk. IV LE, the NCSE Mk. II measures 17.2 W by 3.25 H by 15.7 D, and is rated to deliver 70Wpc. The basic circuit remains the same, with a pair of MOSFET output transformers for each channel. The NCSE Mk. II retained the smaller models speed, transparency, harmonic accuracy, and illuminated-from-within quality, but added improved bass and dynamics, said ST. If you like the Mk. IV LE but feel youre running out of power, the NCSE Mk. II would be the better choice, particularly if youre driving bigger speakers in a bigger room, he advised. (Vol.36 No.11) LFD LE V: 4495 Dr. Richard Bews, proprietor of Englands LFD electronics, has once again upgraded his and Dr. Malcolm O. Hawksfords original integrated amplifier, the 65Wpc LE (n233e Mistral): a perennial ST favorite, owing to its complete lack of convenience or luxury features that degrade sound and add expense. To those ends, all iterations of LFDs solid-state amp have lacked balance and tone controls, headphone jacks, extra sets of speaker outputs, digital displays, and, especially, remote controls. The LE, which Dr. Bews builds in small batches, provides five line-level inputs (but no phono section), and is made with only the highest-quality parts, some vintage (NOS), some custom-made. According to ST, the new LE V151whose improvements all seem to arise from a combination of sturdier casework and more refined parts151is a showstopper. I mean that literally. I didnt want to write I wanted to listen. Compared to the LE IV, which ST owns and loves, the LE V represents a substantial improvement. Everything just fit into place: harmonics, timing, resolution. Quoth he: Buy your LFD LE V today. (Vol.37 No.7) Pass Labs INT-150: 7150 10025 The push-pull, class-AB INT-150 is rated to deliver 150Wpc (191Wpc at clipping), and has a high-quality volume control and five inputs: two XLRRCA and three RCA-only. It uses Passs Super-Symmetry Circuit, previously featured in all X-series models, to naturally eliminate distortions from the audio signal. Though it produced a slightly forward midrange and top end, the INT-150 combined wide dynamic range with great rhythmic drive, a broad soundstage, and tight, tuneful bass, said EL, who recommended high Class B. Measured performance was excellent in most respects, said JA, who feels low Class A is the appropriate rating. (Vol.34 No.1 WWW) PrimaLuna DiaLogue Premium HP: 4399 PrimaLunas DiaLogue Premium HP employs a total of eight power tubes151EL34s are standard, although the user can substitute a variety of other power pentodes151to produce 40Wpc in triode mode or 70Wpc in Ultralinear mode. (On-the-fly switching between modes can be performed with the DiaLogue Premium HPs remote handset.) Additional features include a newly designed, six-tube front end the highest-end implementation yet of PrimaLunas Adaptive AutoBias circuit and an all-tube headphone amp. RD, a fan of the companys earlier ProLogue Premium, found that the new amp provided higher power with no loss of finesse, and declared, PrimaLuna had taken a major step forward in amplifier performance. JAs measurements indicated that PrimaLunas output transformers are of excellent quality. Distortion wasnt the lowest JA has seen, but, fortunately, the distortion is heavily second-harmonic in nature in both modes, even at low frequencies. He concluded that, overall, the PrimaLuna DiaLogue Premium HP measures well for a design using push-pull pairs of EL34 tubes. RD summed up: 4199 for an integrated amp of the DiaLogue Premium HPs level of performance represents excellent value. (Vol.37 No.12 WWW) PrimaLuna DiaLogue Premium: 3399 PrimaLunas top-of-the-line integrated amplifier is rated to deliver 36Wpc with its stock EL34 output tubes or 43Wpc with optional KT120s. It uses PrimaLunas Adaptive AutoBias feature for easy swapping of output tubes, and has a bad-tube indicator, power-transformer protection, and output-transformer protection circuitry. The DiaLogue Premium was extremely quiet and sounded bigger than its power rating suggested, with a rich midrange and an excellent sense of timing, said ST. The DiaLogue Premium will be a dream come true for anyone who has a closetful of output tubes, he concluded. (Vol.36 No.6) PrimaLuna ProLogue Premium: 3399 Designed in Holland and made in China, the solidly built ProLogue Premium is rated to deliver 35Wpc with EL34 tubes or 40Wpc with KT88s. It has a heavy-gauge, ventilated case with a lustrous five-coat finish, features point-to-point wiring, and offers five pairs of RCA input jacks, a Home Theater bypass, and connections for speaker loads of 4 and 8 ohms. Though it lacked the three-dimensional imaging, detailed highs, and extended bass of more expensive amplifiers, the ProLogue Premium produced a natural, inviting midrange and performed well with a wide variety of speakers. The PrimaLuna ProLogue Premium offers outstanding sound quality at a very reasonable price, said RD. JA noted respectable measured performance for a classic tube design. (Vol.35 No.6 WWW) Simaudio Moon Evolution 700i: 14,000 10025 Robustly built of thick, ultrarigid aluminum, the 700i is a fully differential dual-mono design rated to deliver 175Wpc (190Wpc at actual clipping), running in class-A up to 5W and in class-AB thereafter. Its output stages are powered by six bipolar transistors per channel for a wide bandwidth and low noise floor, while its zero global feedback design works to boost the speed of the signal response and eliminate intermodulation distortion. Though it couldnt match the Krell FBIs transient speed or deep-bass extension, the 700i had a full-blooded, dynamic, seamless sound marked by vivid tonal colors, harmonic integrity, and a strong sense of rhythm. With the 700i, I found myself drawn deeper into the music, said FK. (Vol.34 No.3 WWW) TA Power Plant Balanced: 3300 10025 The 140Wpc Power Plant looks almost identical to TAs Music Player, and the two comprise a fully functional audio system in a single stack. Connection via a supplied RJ-12 cable coordinates the functions of the MP and PP, and allows the pair to be operated by a single remote. The PPs switch-mode output stages were developed in-house, and combine MOSFET transistors with high-energy driver modules. JI noted a dynamic-sounding amplifier section that exhibited ample and well-controlled bass along with a smooth, detailed top end. Surprisingly robust and detailed sounding amp for such a small cool-running package, he concludes. (Vol.32 No.8, Vol.35 No.9 WWW) Unison Research S6: 5395 Each channel of the Italian-made S6 uses three EL34 power pentode tubes in a class-A, single-ended, triple-parallel configuration to deliver 35Wpc into 8 ohms. Its distinctive chassis is longitudinally divided into three portions: a central raised center that houses the iron-core transformers is flanked by identical lower sections that hold the tube sockets, bias meters, and bias-adjustment controls. Compared with the Ars-Sonum Filarmona SE, the S6 was more forceful but gave up nothing in finesse when partnered with the Opera Callas loudspeakers, the S6 was fatigue-free, with surprising dynamics and bass, said JM. (Vol.36 No.8 WWW) Cambridge Audio Azur 851A: 1900 First cousin to the Cambridge Azur 851D DAC, the Azur 851A integrated amplifier provides 120Wpc into 8 ohms, two balanced inputs (XLR), eight unbalanced line-level inputs (RCA), and the rare luxury of bass and treble tone controls. HR wrote that he could best describe the sound of the Azur 851A as relaxed and enjoyably colorful, in a class-A triode sort of way. It sounded more naturally toned and weighty than my Creek 3330 or my Line Magnetic LM-518IA, and showed none of that off-putting grayness or brittleness often heard in low-priced, high-powered amps. In his measurements, JA discovered that the amps right-channel performance was not in keeping with that of the left channel151although he suggested that the right channels relative shortcomings were inaudible. His conclusion: Assuming that the less-good performance of its right channel was a sample-specific fault, Cambridge Audios Azur 851A is a well-built amplifier that offers a lot of power with very low distortion at an affordable price. HRs last word: a versatile and extraordinarily musical cornerstone on which to build a truly enjoyable high-end system that can play all types of music with righteous aplomb for little cost. (Vol.38 No.2 WWW) Cayin SP-10A: 2195 10025 With its brushed aluminum faceplate and cabinet of gorgeous cherrywood (walnut and piano lacquer are also available), the 38Wpc SP-10A has a decidedly old-fashioned appearance. It uses four 6L6GC output tubes, two 12AU7 driver tubes, and one 12AX7 input tube has four line-level inputs and offers both 4 and 8 ohm output transformer taps. Though it lacked top-end sparkle and ran out of gas at high volumes, the Cayin offered a lush, natural midrange with outstanding resolution of inner detail and ambience, said BJR. JAs measurements uncovered a curious instability and lack of distortion-free power from the amps 4 ohm tap. (Vol.35 No.4 WWW) Creek Evolution 50A: 1195 Creeks new entry-level model is a class-AB design claimed to deliver 55Wpc into 8 ohms. It offers four single-ended and one balanced input, one of which can accommodate one of three MM or MC plug-in phono boards. The clean front panel has input-selector and Volume knobs, Balance and Tone controls, and a large display. The Creek produced an uncolored midrange, impressive bass impact, and excellent resolution of high-frequency detail, delicacy, and air, said BJR. An involving, flexible, and good-sounding piece of electronics, he concluded, adding that it sounds more powerful than its rating would imply. Considering its affordable price, Creeks Evolution 50A measures fundamentally well, said JA, though he points out that its output stage is underbiased. (Vol.36 No.8 WWW) Croft Phono Integrated: 1895 Crofts 45Wpc Phono Integrated combines in a single package the companys Micro 25 preamplifier and Series 7 power amplifier to create a hybrid integrated in which line - and moving-magnet150compatible phono-stage gain is provided by ECC83 vacuum tubes, output power by transistors. In addition to its phono input, the Croft has three analog line inputs, but offers no remote control, digital inputs, headphone jack, or upgrade paths for USB connectivity. Apart from a small circuit board containing the bipolar timer and relays, the Phono Integrated is hand-wired, point to point, with neatly made solder joins and Bakelite terminal strips. AD liked the Crofts dual-mono volume controls, SM not so much. They agreed, however, that the Crofts sound was extraordinary: smooth, coherent, open, naturally detailed, forceful, physical, and dynamic, with a great sense of space and an expert ability to drive a beat forward. If I were a designer or builder, this is how I would do the thing. If I were buying in this price range, this is the one Id choose, raved AD. On JAs test bench, however, the Croft exhibited a nonflat RIAA response and high levels of harmonic and intermodulation distortion. According to ST, the sound of the Phono Integrated was musical in a way that very few hi-fi components are. Apart from noting this models 1970s-style cosmetics (A pox on cosmetics), minimalist conveniences (A pox on convenience), and slightly plump bass, ST declared the Croft one of the best integrated amplifiers I have ever heard. (Vol.36 No.10, Vol.37 No.5 WWW) HarmanKardon HK 990: 2599 The gorgeous, versatile, 150Wpc HK 990 is a two-channel integrated amplifier with analog and digital inputs, tone controls, bass management, and system equalization. Line-level analog inputs include six pairs single-ended, one pair balanced, a processor HT bypass, and two subwoofer digital inputs include two optical and two coaxial. In addition, there are moving-magnet and moving-coil phono inputs, two subwoofer outputs, two coaxial outputs, and a front-panel headphone jack. Its Analog Devices AD1955 DAC chip handles resolutions up to 24-bit96kHz. Though it was less transparent than the Parasound Halo JC 2 preamp, the HK 990 offered impressive performance with both analog and digital sources, exhibiting taut bass, clean mids, and outstanding power and control. The HK 990 should be on every audiophiles shopping list, said KR, adding that its a harbinger of the future of integrated amplifiers. JA noted that the HKs measured performance was not compromised by its wealth of versatile features. I am impressed, he said. (Vol.34 No.12 WWW) Manley Labs Stingray iTube: 6000 10025 Manley Labs Stingray II: 5650 10025 Direct descendent of the acclaimed Stingray (reviewed by CS in December 1999), the rugged-looking, gorgeously constructed Stingray iTube is built around eight EL84 output tubes, rated to deliver 32Wpc in ultralinear mode and 18Wpc in triode mode. It offers three single-ended inputs, a certified iPod dock, a subwoofer output, and a 14 headphone jack. An IRRF remote control provides full control of the amp, as well as the track functions of a docked iPod. After about 250 hours of break-in, the iTube exhibited a sound marked by elegance, subtlety, and charm. Though it lacked some body and color, and sometimes struggled at high volumes, the iTube had a grainless, extended treble and an overall sound that was engaging and relaxing, said EL. Though it lacked the balanced overall sound of the Simaudio Moon i3.3, the iTube had a midrange to die for, and it effortlessly hung images in the air, summed up EL. The Stingray II is identical to the Stingray iTube, but without the iPod dock. Though it lacked some bass control and low-level resolution, the Stingray II offered a surprisingly dynamic and expansive sound with a relaxed, romantic color, said ST. (Vol.22 No.12, original version, WWW Vol.33 Nos.3, 9, 11, Stingray II WWW) Naim NAIT 5si: 1895 Introduced 30 years after Naim Audios original Nait, the new Nait 5si is a 60Wpc (into 8 ohms) integrated amp with a built-in headphone amp, and with inputs for four line-level sources151but no phono preamp. Inputs are selected with soft-touch buttons, and all are addressed with RCA plugs, while two of those are also equipped with DIN inputs: Naims traditional preference. HR enjoyed the Nait 5si for tracking complex rhythms with perfection, and for keeping even the most microscopic pitch intervals in good focus. The Nait 5si lacked color and spaciousness compared to HRs more expensive tubed integrated, but made it easy to hear151 watch 151the musics rhythms. Forward momentum was spellbinding: The Nait directed my attention toward how the players attacked their instruments. Apart from inverted signal polarity on the headphone output, JA found nothing untoward in his measurements151noting, in fact, that the Nait developed more output power than specified. HR summed up: The Nait 5si is a world-class integrated amplifier that delivers more audio precision and musical enjoyment than any self-respecting anti-imperialist should ever need. (Vol.37 No.10 WWW) Octave Audio V 40 SE: 5300 The entry-level V40 SE Line, from Germanys Octave Audio, is an integrated amplifier with an active line-only preamp section and151despite its model designation151a push-pull output section, using two KT88 pentode tubes per side to produce 40Wpc. (A wide variety of similar pentodes can be used instead, but not all will produce the same amount of power.) The output tubes are operated as true pentodes, and the design entails 10dB of global feedback output-tube bias is user-adjustable via system of which AD remarked, I have never encountered a surer, safer, less ambiguous, or altogether better means of checking and adjusting tube bias. He was similarly impressed by the Octaves musical performance, describing its ability to portray musical timing and momentum as superb. AD also enjoyed the V40 SEs up-front sound and better-than-average sense of scale, also noting that while it didnt sound bright, it had sufficiently extended trebles that reasonable care should be taken in the setup and adjusting of partnering gear. An easy-to-install power-supply enhancement, the Octave Black Box (1200), made an audible improvement, but shouldnt be considered mandatory. JA noted that the V40 SE measured as I would expect from a traditional design that uses a pair of KT88 output tubes for each channel, and praised the amps impressively high standard of construction. (Vol.37 No.8 WWW) Peachtree Audio nova125SE: 1499 The handsome, remote-controlled nova125 combines a 125Wpc amplifier, preamplifier with tubed buffer stage, headphone amp, and asynchronous USB DAC capable of handling resolutions up to 24-bit192kHz. It offers three SPDIF inputs, one analog input, and a preamp output. Though it lacked some resolution, the Peachtree had a slightly warm and soft overall sound, with excellent tonality, well-defined bass, and smooth highs, said ST. Peachtree Audio has delivered a plum, he concluded. Add 100 for Cherry or Rosewood finish. (Vol.36 No.1 WWW) Rogers High Fidelity EHF-100: 7000 Made in the US by former NASA engineer Roger Gibboni, the EHF-100 is rated to deliver 65Wpc (JA measured 35Wpc) into 8 ohms offers four pairs of line-level inputs and uses two EF86 miniature pentode, two 12AX7 triode, and four KT88 power tubes. Fit and finish were excellent. Though not as nuanced, colorful, or dramatic as ADs reference Shindo separates, the EHF-100 distinguished itself as a tight, punchy-sounding amplifier with loads of natural detail, a very good sense of momentum, and an excellent sense of space. Despite differences in the noise floor between its two channels, the EHF-100 measured well for a classic design, said JA. (Vol.35 No.11 WWW) Rogue Sphinx: 1295 The Sphinx is that rarity in contemporary audio: a US-made integrated amplifier with a tubed (12AU7) line stage, a MM-appropriate phono stage, and a headphone jack, all for less than the price of a round-trip ticket to Paris151and Rogue Audio doesnt even make you buy their remote handset (100). Using Bruno Putzeyss Hypex class-D power modules in tandem with a nonswitching power supply, this hybrid integrated delivers 100Wpc into 8 ohms or 200Wpc into 4 ohms. HR enjoyed his time with the Sphinx, noting its greater scale and bass force than his Creek 4330 integrated, and praising its line stage as perhaps the best of its many good features: Everything I played was enjoyably detailed, transparent, and spacious. HRs verdict: Judging by my experiences with the Sphinx, Rogues owner and designer, Mark OBrien, has taken this stigmatized, lower-class mode of operation to a new, more refined level. According to JA, apart from a bit of ultrasonic noise in its output, the Sphinxs amplifier section avoided most of the usual class-D pitfalls, and he particularly praised the MM phono section. (Vol.37 No.8 WWW) Roksan Kandy K2 BT: 1900 This solid-state integrated amp, descended from the original Roksan Kandy K2, is notable for offering both an MM phono stage and a Bluetooth input alongside its three line-level inputs. The Kandy K2 BT, which also provides a pair of preamp-out jacks and a bypass input for AV fans, delivers 140Wpc into 8 ohms and 250Wpc into 4 ohms. In HRs system, The K2 BT showed consistently good tone and scale, but music often felt a tad soft and round151especially at the edges of string plucks and keystrokes. That said, HR declared that the Roksans phono stage was the best Ive heard in a moderately priced integrated151it played LPs in living color. As for Bluetooth, HR was underwhelmed, noting that the detail, life and naturalness exceeded my expectations but I was disappointed by the amount of low-level fuzz and blur I was noticing. He found that Bluetooth music sounded best when playback levels were kept in check. In his measurements, JA echoed that last sentiment151if you use the Roksans BT input, keep your sources volume control down151and commented that the K2 BTs frequency response depends to a larger extent than usual on its volume-control setting. (Vol.37 No.11 WWW) Swissonor V. S.O. P. 5475 The elegant, 8Wpc V. S.O. P. is a push-pull design with three line-level inputs. It uses a pair of ECC81 tubes for the preamp stage, and two pairs of 6V6 power tubes. The V. S.O. P. lacked some of the speed and articulation of the Unison Research Simply Italy, but nevertheless offered a smooth, coherent overall sound, said ST. The V. S.O. P. is an amplifier to hear if you get the chance, especially with high-sensitivity speakers in a small listening space, he concluded. Options: moving-magnet phono stage, add 500 high-output moving-coil phono stage, add 750. (Vol.36 No.2) Unison Research Simply Italy: 2695 10025 The solidly built Simply Italy uses an ECC82 driver tube and an EL34B output tube to deliver 12Wpc. It measures just 10 W by 7.5 H by 15.5 D and offers four line-level inputs, a tape loop, and a single set of outputs optimized for 41508 ohm speakers. Solid-wood inlays around the hefty, stainless-steel volume and selector knobs help damp vibrations. Fit and finish were outstanding. Though it lacked the dimensionality and expansiveness of larger Unison Research amplifiers, the Simply Italy had a confident, solid sound with surprisingly tight bass, said ST. My little bambino. He sums up. Clear, crisp sound, tight bass for all of its 12 watts. ST thinks there may be no better amp for small-group jazz. The Simply Italy was an especially good partner for DeVore Fidelitys Orangutan O93 loudspeakers, said ST. Replacing the amps stock EL34Bs with Genelex KT77 output tubes resulted in an airier sound with less robust bass and improved top-end extension. (Vol.35 No.8 Vol.37 No.1) Arcam FMJ A19: 999 Rated to deliver 50Wpc into 8 ohms, the FMJ A19 is Arcams most affordable integrated amplifier. It provides six line-level inputs, tape and preamplifier outputs, a moving-magnet phono stage, and two front-panel mini-jacks: one for driving headphones, the other for connecting an iPod. While the A19 gets its power from a hefty toroidal transformer, a second internal power supply can deliver a direct, isolated, and regulated 6V to two of Arcams r-series products, such as the rBlink Bluetooth DAC that ST enjoyed. Build quality was excellent, setup simple, operation flawless. Though it lacked some smoothness and drama, the A19 combined a sweet treble, a clean midrange, and well-defined bass for a sound that was fun, involving, and never fatiguing, said SM. JA noted excellent measured performance, but warned that the A19 shouldnt be used to drive at high levels loads much below 6 ohms. Borderline Class B. (Vol.37 No.1 WWW) AVM Inspiration C8: 4190 Made in Germany, the handsome AVM Inspiration C8 is a solid-state CD receiver with a 150Wpc class-D output stage, a phono stage, and digital inputs and outputs, including a USB input limited to 16-bit48kHz resolution. Partnered with the Canalis Anima speakers, the C8 produced a neutral, powerful overall sound, said JM. However, with the speakers placed too low, JM noted an overabundance of high-frequency detail. Expensive for the sound quality on offer. (Vol.36 No.2 WWW) Music Hall a15.3: 549 Rated at 50Wpc into 8 ohms or 75Wpc into 4 ohms, the Music Hall a15.3 is a full-size (16.9 W by 3.1 H by 13.2 D) integrated amplifier that includes a MM phono input, mini-jack and RCA line-level inputs, and a front-panel headphone jack. SM admired the a15.3s high level of fit and finish, adding that the amp performed without flaw in his system. Using the a15.3 with Music Halls companion c15.3 CD player150DAC and comparing it with NADs C 515BEE CD player and C 316BEE integrated amplifier, SM found that the a15.3 sounded more open and airy, and produced a wider, deeper soundstage with beautifully focused images, although it lacked the NADs intangible smoothness and musical flow. Among the inputs offered, none impressed SM more than the a15.3s phono stage, which sounded superb151quiet, dynamic, and emotionally compelling. (Vol.37 No.6 WWW) NAD D 3020: 499 Launched to celebrate NADs 40th anniversary, the 30Wpc D 3020 takes only its name from the companys iconic 3020 integrated amplifier every other aspect of the design has been thoroughly modernized. It uses a switch-mode power supply, lacks a phono stage, and has only a single analog input, but includes a front-panel headphone minijack an optional 6dB bass boost a subwoofer output coaxial, optical, and 24-bit96kHz-capable asynchronous USB inputs and uses an audio-optimized aptX codec for Bluetooth streaming. Weighing just 3 lbs and measuring an unusual 7 38 H by 2 516 W by 8 58 D, the D 3020 can be placed horizontally, like a traditional component, or stood upright, like a modem or hard drive. Uncommonly sensual for a hi-fi product, it has a large, textured volume knob soft, smooth side panels and a touchscreen that occupies its entire front panel and extends through one entire side panel. The sound from every input was warm, present, and naturally detailed even low-quality MP3s streamed wirelessly via Bluetooth were engaging, said SM. Right now, NADs D 3020 is the best bargain in all of hi-fi, added ST. Borderline Class B. (Vol.36 Nos. 11 12 WWW) NAD C 316BEE: 379 10025 Descendant of NADs famed 3020 integrated amplifier, the 40Wpc C 316BEE uses a new variant of the PowerDrive technology found in NADs Master Series components, said to maximize the short-term dynamic power sent to loudspeakers. It has five inputs, a single set of user-friendly binding posts for easy connections, defeatable tone controls, a headphone jack, and an iPod minijack. The NAD matched power with grace, providing a rich, forceful overall presentation and an impressive ability to follow complex musical passages and make clear, truthful distinctions among musical instruments. Compared to the JoLida FX 10, the NAD produced a far more compelling listening experience, with faster attacks, longer decays, and a wider soundstage, said SM. (Vol.34 No.7 WWW) Outlaw Audio RR2150: 699 10025 This 100Wpc, two-channel receiver showcases stylish, deco-like looks and a full range of features that include line, iPod, phono, and USB digital inputs, tape and processor loops, tone controls, headphone output, speaker equalization, bass management, and a mono line-level subwoofer output. JA was astonished to discover what the bargain-basement-priced RR2150 offered, both on the test bench and in the listening room. The RR2150s self-explanatory setup, versatility and convenience, and open, focused, and well-organized overall sound (though somewhat opaque and not fully fleshed out) make it a great intro to hi-fi for a younger generation, said MF. Problems with production led to delivery delays through July 2006, but the situation is now resolved. Current production samples (made in a different factory) offer the same excellent measured performance as the original, but the RR2150s USB digital input, marred by limited resolution and high jitter, should be regarded as being for convenience only, advised JA. (Vol.29 No.3, Vol.31 No.1 WWW) Rega Brio - R . 995 10025 Minimalist in design and appearance, the 50Wpc Brio-R measures just 8.5 W by 3.25 H by 13 D and, like the Rega DAC, is housed in an attractive aluminum-and-steel case with a reflective front panel. It offers five line-level RCA inputs and one phono input. Though it lacked the definition, detail, focus, and frequency extension of the much more expensive LFD LE IV, the Brio-R delivered a relaxed, nonfatiguing sound with tight, full bass, said ST. The Brio-R showed the excellence thats possible when a manufacturer aspires to deliver less, he said, adding that it includes a very good moving-magnet phono stage, enough to satisfy the less fremerous among us. Yes, its umble eye-fye, but very well done, ST sums up. (Vol.34 No.12) Lepai LP7498E: 99.90 Rated to deliver 100Wpc via its TriPath class-D output stage, the Lepai is a small (4.5 W by 1.25 H by 7 D) integrated amplifier with one pair of RCA inputs, two pairs of speaker binding posts, and a dedicated 36V DC power supply. It uses STMicroelectronics TDA7498 class-D module and supports Bluetooth streaming but not aptX. CDs played through the Lepais RCA input sounded big, bold, and emotionally compelling, with a natural midrange, sweet highs, good bass weight, and well-focused images, but digital files streamed via Bluetooth sounded gritty, compressed, and murky, said SM. Sold by Parts Express with a 45-day money-back guarantee and lifetime service warranty. (Vol.37 No.2 WWW) Hegel H160, PS Audio Sprout, Onkyo TX-8020. Allnic T-1500 300B, Audio Note Jinro, not auditioned in too long a time to be sure of rating Devialet D-Premier discontinued.
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