{"id":269,"date":"2014-06-30T19:28:35","date_gmt":"2014-06-30T19:28:35","guid":{"rendered":"http:\/\/voyager3.com\/?page_id=269"},"modified":"2025-07-19T17:18:53","modified_gmt":"2025-07-19T15:18:53","slug":"les-encodeurs-absolus","status":"publish","type":"page","link":"https:\/\/voyager3.com\/?page_id=269","title":{"rendered":"Les encodeurs absolus"},"content":{"rendered":"<p style=\"text-align: justify;\"><span style=\"color: #ff0000;\"><strong>La petite histoire&#8230;<\/strong><\/span><\/p>\n<table  class=\" table table-hover\" style=\"border-collapse: collapse; width: 100%;\">\n<tbody>\n<tr>\n<td style=\"width: 21.4286%;\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_prog.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"311\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=311\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_prog.jpg?fit=733%2C570&amp;ssl=1\" data-orig-size=\"733,570\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"vue_prog\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;Ce que voit la webcam&lt;\/p&gt;\n\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_prog.jpg?fit=648%2C504&amp;ssl=1\" class=\"alignleft wp-image-311\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_prog.jpg?resize=159%2C123&#038;ssl=1\" alt=\"Ce que voit la webcam\" width=\"159\" height=\"123\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_prog.jpg?resize=300%2C233&amp;ssl=1 300w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_prog.jpg?resize=642%2C500&amp;ssl=1 642w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_prog.jpg?w=733&amp;ssl=1 733w\" sizes=\"auto, (max-width: 159px) 100vw, 159px\" \/><\/a><\/td>\n<td style=\"width: 78.5714%; text-align: justify;\">En 2003, avant m\u00eame que le projet de construction de l&rsquo;observatoire soit pr\u00e9cis\u00e9, nous avions pour id\u00e9e d&rsquo;\u00e9quiper le futur t\u00e9lescope d&rsquo;un syst\u00e8me de positionnement pr\u00e9cis et peu co\u00fbteux. Michel, en discutant avec S\u00e9bastien, \u00e9voquait la lecture de graduation d\u00e9port\u00e9e gr\u00e2ce \u00e0 un syst\u00e8me de webcam&#8230; afin de m\u00e9nager le dos des utilisateurs. En reprenant cette id\u00e9e, S\u00e9bastien a extrapol\u00e9 ce principe en lisant \u00e0 la webcam des graduations binaires interpr\u00e9t\u00e9 par l&rsquo;ordinateur.\u00a0 Sur cette page est pr\u00e9sent\u00e9e le grande ligne de cette r\u00e9alisation.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"text-align: justify;\"><strong>R\u00e9alisation d&rsquo;un encodeur absolu \u00e0 l&rsquo;aide d&rsquo;une webcam<\/strong><\/p>\n<ul style=\"text-align: justify;\">\n<li style=\"text-align: left;\"><em>Etat des lieux<\/em><\/li>\n<\/ul>\n<p style=\"padding-left: 60px; text-align: justify;\">Les syst\u00e8mes Go-To sont aujourd&rsquo;hui d&rsquo;utilisation courante. Notre t\u00e9lescope \u00e9tant pilot\u00e9 par un syst\u00e8me PIC-Astro, le pilotage et le via un logiciel de cartographie utilisant le protocole LX200 poss\u00e8de un tel syst\u00e8me.<\/p>\n<p style=\"text-align: justify; padding-left: 60px;\">Toutefois, comme bon nombre de syst\u00e8me Go-To, Arduin&rsquo;astro utilise un positionnement relatif. Ainsi, il faut pointer un point de r\u00e9f\u00e9rence, typiquement une \u00e9toile, afin que le t\u00e9lescope se d\u00e9place par la suite sur l&rsquo;objet rechercher. En cons\u00e9quence, la manipulation manuelle n&rsquo;est pas possible le risque \u00e9tant de perdre la r\u00e9f\u00e9rence.<\/p>\n<table  class=\" table table-hover\" style=\"border-collapse: collapse; width: 100%; height: 157px;\">\n<tbody>\n<tr style=\"height: 157px;\">\n<td style=\"width: 74.6429%; text-align: justify; height: 157px;\">Il est usuel dans le monde amateur d&rsquo;utiliser des encodeurs incr\u00e9mentaux et donc relatif, soit du commerce, soit en d\u00e9tournant l&rsquo;utilisation premi\u00e8re d&rsquo;un syst\u00e8me (syst\u00e8me \u00e0 base de souris, de capteur optique) soit encore en comptant le nombre de pas d&rsquo;un moteur (cas de Arduin&rsquo;astro).<\/td>\n<td style=\"width: 25.3571%; height: 157px;\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/enco_re.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"299\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=299\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/enco_re.jpg?fit=398%2C333&amp;ssl=1\" data-orig-size=\"398,333\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"enco_re\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/enco_re.jpg?fit=398%2C333&amp;ssl=1\" class=\"wp-image-299 alignleft\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/enco_re.jpg?resize=196%2C164&#038;ssl=1\" alt=\"enco_re\" width=\"196\" height=\"164\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/enco_re.jpg?resize=300%2C251&amp;ssl=1 300w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/enco_re.jpg?w=398&amp;ssl=1 398w\" sizes=\"auto, (max-width: 196px) 100vw, 196px\" \/><\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Les raisons principales de ce choix sont une question de co\u00fbt et de simplicit\u00e9 de mise en \u0153uvre.<\/p>\n<table  class=\" table table-hover\" style=\"border-collapse: collapse; width: 100%;\">\n<tbody>\n<tr>\n<td style=\"width: 74.4048%;\">Ainsi, les encodeurs absolus restent peu utiliser notamment en raison qu&rsquo;une pr\u00e9cision raisonnable est associ\u00e9e \u00e0 un certain co\u00fbt. La r\u00e9alisation d&rsquo;un syst\u00e8me permettant de coder l&rsquo;information sous forme d&rsquo;un code Gray et de le lire est plus complexe.<\/td>\n<td style=\"width: 25.5952%;\">\u00a0<a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/enco_ab.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"300\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=300\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/enco_ab.jpg?fit=344%2C348&amp;ssl=1\" data-orig-size=\"344,348\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"enco_ab\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/enco_ab.jpg?fit=344%2C348&amp;ssl=1\" class=\"alignright wp-image-300\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/enco_ab.jpg?resize=160%2C162&#038;ssl=1\" alt=\"enco_ab\" width=\"160\" height=\"162\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/enco_ab.jpg?resize=296%2C300&amp;ssl=1 296w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/enco_ab.jpg?w=344&amp;ssl=1 344w\" sizes=\"auto, (max-width: 160px) 100vw, 160px\" \/><\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<ul>\n<li>Notre solution<\/li>\n<\/ul>\n<table  class=\" table table-hover\" style=\"border-collapse: collapse; width: 100%; height: 23px;\">\n<tbody>\n<tr style=\"height: 23px;\">\n<td style=\"width: 24.0476%; height: 23px;\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/webcam.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"301\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=301\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/webcam.jpg?fit=205%2C186&amp;ssl=1\" data-orig-size=\"205,186\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"webcam\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/webcam.jpg?fit=205%2C186&amp;ssl=1\" class=\"wp-image-301 aligncenter\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/webcam.jpg?resize=112%2C102&#038;ssl=1\" alt=\"webcam\" width=\"112\" height=\"102\" \/><\/a><\/td>\n<td style=\"width: 75.9524%; height: 23px;\">Nous pr\u00e9sentons ici la r\u00e9alisation d&rsquo;un encodeur absolu \u00e0 l&rsquo;aide d&rsquo;une webcam mise en \u0153uvre sur notre t\u00e9lescope.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<table  class=\" table table-hover\" style=\"border-collapse: collapse; width: 100%; height: 70px;\">\n<tbody>\n<tr style=\"height: 70px;\">\n<td style=\"width: 77.2619%; height: 70px;\">En terme d&rsquo;achat, cela correspond \u00e0 l&rsquo;acquisition de deux webcams, une part axe, et \u00e0 l&rsquo;impression d&rsquo;un code Gray \u00e0 l&rsquo;aide d&rsquo;une imprimante.<\/td>\n<td style=\"width: 22.7381%; height: 70px;\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/printer.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"302\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=302\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/printer.jpg?fit=383%2C438&amp;ssl=1\" data-orig-size=\"383,438\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"printer\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/printer.jpg?fit=383%2C438&amp;ssl=1\" class=\"alignnone  wp-image-302\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/printer.jpg?resize=121%2C138&#038;ssl=1\" alt=\"\" width=\"121\" height=\"138\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/printer.jpg?w=383&amp;ssl=1 383w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/printer.jpg?resize=262%2C300&amp;ssl=1 262w\" sizes=\"auto, (max-width: 121px) 100vw, 121px\" \/><\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"text-align: justify; padding-left: 60px;\">L&rsquo;impression d&rsquo;un code Gray \u00e0 l&rsquo;aide d&rsquo;une imprimante et le montage de celui-ci sur un support comporte \u00e9videmment de large impression qu&rsquo;il faut corriger par un \u00e9talonnage des graduations. Dans le cas contraire, la pr\u00e9cision du syst\u00e8me est largement en dessous de ce que l&rsquo;on attend d&rsquo;un tel syst\u00e8me de positionnement.<\/p>\n<figure id=\"attachment_303\" class=\"thumbnail wp-caption alignright\" style=\"width: 337px\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/proto.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"303\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=303\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/proto.jpg?fit=545%2C362&amp;ssl=1\" data-orig-size=\"545,362\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"proto\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/proto.jpg?fit=545%2C362&amp;ssl=1\" class=\"wp-image-303 \" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/proto.jpg?resize=327%2C217&#038;ssl=1\" alt=\"proto\" width=\"327\" height=\"217\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/proto.jpg?resize=300%2C199&amp;ssl=1 300w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/proto.jpg?w=545&amp;ssl=1 545w\" sizes=\"auto, (max-width: 327px) 100vw, 327px\" \/><\/a><figcaption class=\"caption wp-caption-text\">Le prototype utilis\u00e9 lors des tests<\/figcaption><\/figure>\n<p style=\"text-align: justify; padding-left: 60px;\">Une r\u00e9solution de 640&#215;480 est une valeur courante pour les webcams. La plage de r\u00e9glage de la nettet\u00e9 de l&rsquo;image de la webcam permet d&rsquo;observer clairement un objet de l&rsquo;ordre de 9 mm de largeur. La r\u00e9solution spatiale de la webcam dans ce cas est de 14 \u03bcm.<\/p>\n<p style=\"text-align: justify; padding-left: 60px;\">Compte tenu des dimensions de notre t\u00e9lescope, l&rsquo;utilisation de 4 bandes de feuille A4 (297mm de longueur) est retenue pour la r\u00e9alisation du disque supportant le code Gray.<\/p>\n<p style=\"text-align: justify; padding-left: 60px;\">Nous utiliserons la valeur de 360mm afin de tenir compte des marges d&rsquo;impression. Ainsi le p\u00e9rim\u00e8tre du disque sera de 1131 mm.<\/p>\n<p style=\"text-align: justify; padding-left: 60px;\">La r\u00e9solution angulaire th\u00e9orique de l&rsquo;encodeur absolu sera donc de 16 bits<\/p>\n<p style=\"text-align: justify; padding-left: 60px;\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/bande.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"304\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=304\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/bande.jpg?fit=982%2C527&amp;ssl=1\" data-orig-size=\"982,527\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"bande\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/bande.jpg?fit=648%2C348&amp;ssl=1\" class=\"alignleft wp-image-304\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/bande.jpg?resize=422%2C225&#038;ssl=1\" alt=\"bande\" width=\"422\" height=\"225\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/bande.jpg?resize=300%2C160&amp;ssl=1 300w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/bande.jpg?w=982&amp;ssl=1 982w\" sizes=\"auto, (max-width: 422px) 100vw, 422px\" \/><\/a>Nous avons r\u00e9alis\u00e9 un programme g\u00e9n\u00e9rant un code Gray 14 bits imprimable.<\/p>\n<p style=\"text-align: justify; padding-left: 60px;\">Le choix d&rsquo;un code 14 bits est en raison de la limitation en r\u00e9solution de l&rsquo;impression.<br \/>Toutefois, la lecture pouvant se faire \u00e0 une pr\u00e9cision au-del\u00e0 des 14 bits, le bit de poids faible correspondant \u00e0 environ 5 pixels sur l&rsquo;image de la webcam, la r\u00e9solution effective de lecture n&rsquo;est pas limit\u00e9e par ce choix du code Gray.<\/p>\n<ul>\n<li>Difficult\u00e9s et solutions<\/li>\n<\/ul>\n<p style=\"padding-left: 60px; text-align: justify;\">Le programme de lecture des webcams doit traiter les images en temps r\u00e9el. La m\u00e9thode d&rsquo;interpr\u00e9tation de l&rsquo;image doit \u00eatre :<\/p>\n<ul style=\"padding-left: 90px; text-align: justify;\">\n<li>Adapt\u00e9e \u00e0 l&rsquo;orientation de l&rsquo;image<\/li>\n<li>Peu sensible \u00e0 la poussi\u00e8re<\/li>\n<li>Peu sensible au d\u00e9faut d&rsquo;\u00e9clairage de la bande<\/li>\n<li>Non perturb\u00e9e au niveau de la jonction des bandes<\/li>\n<li>Corrig\u00e9e la distorsion de l&rsquo;image par l&rsquo;optique de la webcam et\u00a0 la courbure de la bande sur son support<\/li>\n<li>\u00a0Telle que la bande soit \u00e9talonn\u00e9e afin de compenser les irr\u00e9gularit\u00e9s d&rsquo;impression et de montage de la bande<\/li>\n<\/ul>\n<p style=\"padding-left: 60px; text-align: justify;\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vu_webcam.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"305\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=305\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vu_webcam.jpg?fit=586%2C445&amp;ssl=1\" data-orig-size=\"586,445\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"vu_webcam\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vu_webcam.jpg?fit=586%2C445&amp;ssl=1\" class=\"alignright size-medium wp-image-305\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vu_webcam.jpg?resize=300%2C227&#038;ssl=1\" alt=\"vu_webcam\" width=\"300\" height=\"227\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vu_webcam.jpg?resize=300%2C227&amp;ssl=1 300w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vu_webcam.jpg?resize=175%2C131&amp;ssl=1 175w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vu_webcam.jpg?w=586&amp;ssl=1 586w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a>Ainsi, le programme que nous avons r\u00e9alis\u00e9 d\u00e9termine en temps r\u00e9el l&rsquo;orientation de la bande et est robuste gr\u00e2ce \u00e0 l&rsquo;utilisation de m\u00e9thodes num\u00e9riques telles que les transform\u00e9s de Fourrier et l&rsquo;ajustement de mod\u00e8le th\u00e9orique par m\u00e9thode des moindres carr\u00e9s<\/p>\n<p style=\"text-align: justify; padding-left: 60px;\">On s&rsquo;affranchit des erreurs de lecture, lors du passage d&rsquo;une jonction de bande devant la webcam, o\u00f9 lors\u00a0 de la pr\u00e9sence de poussi\u00e8re sur la bande, par la lecture de plusieurs graduations, en l&rsquo;occurrence 4 zones de lectures, sur une m\u00eame image.<\/p>\n<p style=\"text-align: justify; padding-left: 60px;\">La distorsion de l&rsquo;image par l&rsquo;optique de la webcam et la courbure de la bande sur son support sont mod\u00e9lis\u00e9es par l&rsquo;observation d&rsquo;une grille de calibration.<\/p>\n<p style=\"text-align: justify; padding-left: 60px;\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Grilles.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"306\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=306\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Grilles.jpg?fit=1047%2C417&amp;ssl=1\" data-orig-size=\"1047,417\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"Grilles\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Grilles.jpg?fit=648%2C258&amp;ssl=1\" class=\"aligncenter wp-image-306\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Grilles.jpg?resize=492%2C195&#038;ssl=1\" alt=\"Grilles\" width=\"492\" height=\"195\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Grilles.jpg?resize=300%2C119&amp;ssl=1 300w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Grilles.jpg?resize=1024%2C407&amp;ssl=1 1024w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Grilles.jpg?resize=1025%2C408&amp;ssl=1 1025w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Grilles.jpg?w=1047&amp;ssl=1 1047w\" sizes=\"auto, (max-width: 492px) 100vw, 492px\" \/><\/a>Afin de r\u00e9aliser l&rsquo;\u00e9talonnage nous devons utiliser une\u00a0 longueur r\u00e9f\u00e9rence. Le principe de lecture du code par la webcam nous donne une telle r\u00e9f\u00e9rence.<\/p>\n<p style=\"text-align: justify; padding-left: 60px;\">Nous r\u00e9alisons deux lectures sur le m\u00eame champ de vue. La distance entre les\u00a0 deux lignes de lecture est fix\u00e9e \u00e0 288 pixels. Ainsi, quelle que soit la position du disque de lecture cette distance est de 288 pixels.<\/p>\n<p style=\"text-align: justify; padding-left: 60px;\">La r\u00e9f\u00e9rence fixe choisie est le nombre de pixels n\u00e9cessaires afin de r\u00e9aliser un tour complet du disque d&rsquo;encodage.<\/p>\n<figure id=\"attachment_307\" class=\"thumbnail wp-caption aligncenter\" style=\"width: 467px\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/3vues.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"307\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=307\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/3vues.jpg?fit=1067%2C394&amp;ssl=1\" data-orig-size=\"1067,394\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"3vues\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;Images individuelles de 480 pixels de largeur&lt;\/p&gt;\n\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/3vues.jpg?fit=648%2C239&amp;ssl=1\" class=\" wp-image-307\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/3vues.jpg?resize=457%2C168&#038;ssl=1\" alt=\"Images individuelles de 480 pixels de largeur \" width=\"457\" height=\"168\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/3vues.jpg?resize=300%2C110&amp;ssl=1 300w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/3vues.jpg?resize=1024%2C378&amp;ssl=1 1024w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/3vues.jpg?resize=1025%2C378&amp;ssl=1 1025w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/3vues.jpg?w=1067&amp;ssl=1 1067w\" sizes=\"auto, (max-width: 457px) 100vw, 457px\" \/><\/a><figcaption class=\"caption wp-caption-text\">Images individuelles de 480 pixels de largeur<\/figcaption><\/figure>\n<p style=\"padding-left: 60px;\">Principe d&rsquo;\u00ab\u00a0assemblage\u00a0\u00bb\u00a0 afin de comptabiliser le nombre de pixel pour couvrir un tour complet.<\/p>\n<p style=\"text-align: justify; padding-left: 60px;\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/3vues_fusion.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"308\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=308\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/3vues_fusion.jpg?fit=824%2C539&amp;ssl=1\" data-orig-size=\"824,539\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"3vues_fusion\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/3vues_fusion.jpg?fit=648%2C424&amp;ssl=1\" class=\"aligncenter wp-image-308\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/3vues_fusion.jpg?resize=378%2C247&#038;ssl=1\" alt=\"3vues_fusion\" width=\"378\" height=\"247\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/3vues_fusion.jpg?resize=300%2C196&amp;ssl=1 300w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/3vues_fusion.jpg?resize=764%2C500&amp;ssl=1 764w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/3vues_fusion.jpg?w=824&amp;ssl=1 824w\" sizes=\"auto, (max-width: 378px) 100vw, 378px\" \/><\/a>A chaque valeur du code Gray est associ\u00e9e une graduation angulaire bas\u00e9 sur la graduation de la bande en pixel, qui est une graduation suffisamment r\u00e9guli\u00e8re.<\/p>\n<ul>\n<li><strong>L&rsquo;ennemi num\u00e9ro 1 : La dilatation<\/strong><\/li>\n<\/ul>\n<p style=\"padding-left: 60px;\">On ne peut s&rsquo;affranchir totalement des effets de dilatation&#8230; mais on peut essayer de minimiser leurs influences.<\/p>\n<p style=\"text-align: justify; padding-left: 60px;\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dila.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"309\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=309\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dila.jpg?fit=1117%2C388&amp;ssl=1\" data-orig-size=\"1117,388\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"dila\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dila.jpg?fit=648%2C225&amp;ssl=1\" class=\"alignright wp-image-309\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dila.jpg?resize=426%2C148&#038;ssl=1\" alt=\"dila\" width=\"426\" height=\"148\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dila.jpg?resize=300%2C104&amp;ssl=1 300w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dila.jpg?resize=1024%2C355&amp;ssl=1 1024w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dila.jpg?resize=1025%2C356&amp;ssl=1 1025w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dila.jpg?w=1117&amp;ssl=1 1117w\" sizes=\"auto, (max-width: 426px) 100vw, 426px\" \/><\/a>Pour minimiser les effets de dilatation, les bandes imprim\u00e9es sur du calque polyester sont mont\u00e9es tendues sur des disques en aluminium.<\/p>\n<ul style=\"text-align: justify;\">\n<li>La r\u00e9alisation<\/li>\n<\/ul>\n<p style=\"padding-left: 60px;\">Le support en aluminium, comme le reste du t\u00e9lescope, a \u00e9t\u00e9 r\u00e9alis\u00e9 au sein de l&rsquo;association. Le support de la webcam a \u00e9t\u00e9 modifi\u00e9 afin de l&rsquo;int\u00e9grer plus facilement sur la monture. Deux leds ont \u00e9t\u00e9 rajout\u00e9es afin d&rsquo;\u00e9clairer le code Gray pendant l&rsquo;observation (qui a priori se passe la nuit&#8230;).<\/p>\n<p style=\"text-align: justify; padding-left: 60px;\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/ensemble.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"310\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=310\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/ensemble.jpg?fit=730%2C608&amp;ssl=1\" data-orig-size=\"730,608\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"ensemble\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/ensemble.jpg?fit=648%2C540&amp;ssl=1\" class=\"aligncenter wp-image-310\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/ensemble.jpg?resize=358%2C297&#038;ssl=1\" alt=\"ensemble\" width=\"358\" height=\"297\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/ensemble.jpg?resize=300%2C249&amp;ssl=1 300w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/ensemble.jpg?resize=600%2C500&amp;ssl=1 600w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/ensemble.jpg?w=730&amp;ssl=1 730w\" sizes=\"auto, (max-width: 358px) 100vw, 358px\" \/><\/a><\/p>\n<ul style=\"text-align: justify;\">\n<li>Dans la pratique<\/li>\n<\/ul>\n<figure id=\"attachment_311\" class=\"thumbnail wp-caption alignleft\" style=\"width: 261px\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_prog.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"311\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=311\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_prog.jpg?fit=733%2C570&amp;ssl=1\" data-orig-size=\"733,570\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"vue_prog\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;Ce que voit la webcam&lt;\/p&gt;\n\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_prog.jpg?fit=648%2C504&amp;ssl=1\" class=\"wp-image-311\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_prog.jpg?resize=251%2C195&#038;ssl=1\" alt=\"\" width=\"251\" height=\"195\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_prog.jpg?resize=300%2C233&amp;ssl=1 300w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_prog.jpg?resize=642%2C500&amp;ssl=1 642w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_prog.jpg?w=733&amp;ssl=1 733w\" sizes=\"auto, (max-width: 251px) 100vw, 251px\" \/><\/a><figcaption class=\"caption wp-caption-text\">Ce que voit la webcam<\/figcaption><\/figure>\n<p>\u00a0<\/p>\n<figure id=\"attachment_312\" class=\"thumbnail wp-caption alignleft\" style=\"width: 223px\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_util.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"312\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=312\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_util.jpg?fit=554%2C499&amp;ssl=1\" data-orig-size=\"554,499\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"vue_util\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;Ce que voit l&amp;rsquo;utilisateur&lt;\/p&gt;\n\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_util.jpg?fit=554%2C499&amp;ssl=1\" class=\"wp-image-312\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_util.jpg?resize=213%2C192&#038;ssl=1\" alt=\"Ce que voit l'utilisateur\" width=\"213\" height=\"192\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_util.jpg?resize=300%2C270&amp;ssl=1 300w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/vue_util.jpg?w=554&amp;ssl=1 554w\" sizes=\"auto, (max-width: 213px) 100vw, 213px\" \/><\/a><figcaption class=\"caption wp-caption-text\">Ce que voit l&rsquo;utilisateur<\/figcaption><\/figure>\n<p>\u00a0<\/p>\n<figure id=\"attachment_313\" class=\"thumbnail wp-caption alignleft\" style=\"width: 223px\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/cdc.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"313\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=313\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/cdc.jpg?fit=682%2C615&amp;ssl=1\" data-orig-size=\"682,615\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"cdc\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;Ce que voit carte du ciel&lt;\/p&gt;\n\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/cdc.jpg?fit=648%2C584&amp;ssl=1\" class=\"wp-image-313\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/cdc.jpg?resize=213%2C192&#038;ssl=1\" alt=\"Ce que voit carte du ciel\" width=\"213\" height=\"192\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/cdc.jpg?resize=300%2C270&amp;ssl=1 300w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/cdc.jpg?resize=554%2C500&amp;ssl=1 554w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/cdc.jpg?w=682&amp;ssl=1 682w\" sizes=\"auto, (max-width: 213px) 100vw, 213px\" \/><\/a><figcaption class=\"caption wp-caption-text\">Ce que voit carte du ciel<\/figcaption><\/figure>\n<p style=\"text-align: justify; padding-left: 60px;\">Dans la pratique on pointe \u00e0 la main pour \u00eatre proche de l&rsquo;objet. On termine par un Go-To \u00e0 l&rsquo;aide du logiciel de cartographie. Cette m\u00e9thode permet de gagner du temps de pointage sans avoir besoin d&rsquo;un Go-to rapide, c&rsquo;est \u00e0 dire des moteurs puissants.<\/p>\n<ul style=\"text-align: justify;\">\n<li>Cot\u00e9 mat\u00e9riel<\/li>\n<\/ul>\n<p style=\"text-align: justify; padding-left: 60px;\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2025\/07\/image1-1.png?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"3480\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=3480\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2025\/07\/image1-1.png?fit=696%2C628&amp;ssl=1\" data-orig-size=\"696,628\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"image1\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2025\/07\/image1-1.png?fit=648%2C585&amp;ssl=1\" class=\"wp-image-3480 alignright\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2025\/07\/image1-1.png?resize=240%2C217&#038;ssl=1\" alt=\"\" width=\"240\" height=\"217\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2025\/07\/image1-1.png?w=696&amp;ssl=1 696w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2025\/07\/image1-1.png?resize=300%2C271&amp;ssl=1 300w\" sizes=\"auto, (max-width: 240px) 100vw, 240px\" \/><\/a>Le programme d&rsquo;encodage tourne sur un PC linux. Le\u00a0programme g\u00e8re 2 webcams, une pour chaque axe, et supervise les communications suivant le protocole LX200 entre le circuit de commande des moteurs pas-\u00e0-pas (Arduin&rsquo;astro) et le logiciel de cartographie (Stellarium).<\/p>\n<p style=\"text-align: justify; padding-left: 60px;\">Le principe est de laisser faire le plus possible la communication entre arduin&rsquo;astro et la cartographie. Le programme d&rsquo;encodage corrige les coordonn\u00e9es uniquement si l&rsquo;\u00e9cart entre les coordonn\u00e9es de PIC-astro et celles donn\u00e9es par les webcams est trop important (typiquement si l&rsquo;\u00e9cart est sup\u00e9rieur \u00e0 1 minute d&rsquo;arc). Cet \u00e9cart provient des d\u00e9fauts g\u00e9om\u00e9trique de la monture, de la mise en station des effets de r\u00e9fraction atmosph\u00e9rique, d\u00e9fauts mesur\u00e9s et compens\u00e9s par les mod\u00e8les int\u00e9gr\u00e9s au programme d&rsquo;encodage.<\/p>\n<ul style=\"text-align: justify;\">\n<li>Bilan<\/li>\n<\/ul>\n<p style=\"padding-left: 60px; text-align: justify;\">De cette fa\u00e7on on peut profiter de la pr\u00e9cision de l&rsquo;encodage relatif d&rsquo;arduin&rsquo;astro et manipuler \u00e0 la main le t\u00e9lescope sans perdre le positionnement gr\u00e2ce \u00e0 l&rsquo;encodage absolu.<\/p>\n<p style=\"text-align: justify; padding-left: 60px;\">Le code d&rsquo;environ 20000 lignes est r\u00e9alis\u00e9 en C++ et en JAVA pour la partie interface graphique et comporte 4 fonctionnalit\u00e9s principales:<\/p>\n<ul>\n<li>Documents de conception<\/li>\n<li style=\"list-style-type: none;\">\n<ul>\n<li>\u00c9talonnage des bandes de lecture avec correction des distorsions optiques et de l&rsquo;effet de courbure du disque sur la lecture des bandes.<\/li>\n<li>Interpr\u00e9tation des images des webcams \/ gestions des communications LX200 entre arduin&rsquo;astro et le logiciel de cartographie.<\/li>\n<li>Mesure et corrections des d\u00e9fauts g\u00e9om\u00e9triques de la monture<\/li>\n<li>Visualisation de la lecture du code Gray pour le d\u00e9buggage et pour l&rsquo;int\u00e9r\u00eat p\u00e9dagogique.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<table  class=\" table table-hover\" style=\"border-collapse: collapse; width: 100%; height: 115px;\">\n<tbody>\n<tr style=\"height: 69px;\">\n<td style=\"width: 14.4048%; height: 69px;\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dossier_enco.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"315\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=315\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dossier_enco.jpg?fit=144%2C207&amp;ssl=1\" data-orig-size=\"144,207\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"dossier_enco\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dossier_enco.jpg?fit=144%2C207&amp;ssl=1\" class=\"wp-image-315 aligncenter\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dossier_enco.jpg?resize=32%2C46&#038;ssl=1\" alt=\"dossier_enco\" width=\"32\" height=\"46\" \/><\/a><\/td>\n<td style=\"width: 85.5952%; height: 69px;\">Conception encodeur (<strong><a href=\"https:\/\/voyager3.com\/documents\/conception_EncodeurAbsolu.pdf\">pdf<\/a><\/strong>)<\/td>\n<\/tr>\n<tr style=\"height: 23px;\">\n<td style=\"width: 14.4048%; height: 23px;\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dossier_enco.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"315\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=315\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dossier_enco.jpg?fit=144%2C207&amp;ssl=1\" data-orig-size=\"144,207\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"dossier_enco\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dossier_enco.jpg?fit=144%2C207&amp;ssl=1\" class=\"wp-image-315 aligncenter\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dossier_enco.jpg?resize=32%2C46&#038;ssl=1\" alt=\"dossier_enco\" width=\"32\" height=\"46\" \/><\/a><\/td>\n<td style=\"width: 85.5952%; height: 23px;\">Mod\u00e9lisation des d\u00e9fauts d&rsquo;une monture \u00e9quatoriale (<strong><a href=\"https:\/\/voyager3.com\/wp-content\/uploads\/2015\/10\/Corrections_Defauts_Geometriques_d_une_Monture.pdf\">pdf<\/a><\/strong>)<\/td>\n<\/tr>\n<tr style=\"height: 23px;\">\n<td style=\"width: 14.4048%; height: 23px;\"><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dossier_enco.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"315\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=315\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dossier_enco.jpg?fit=144%2C207&amp;ssl=1\" data-orig-size=\"144,207\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"dossier_enco\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dossier_enco.jpg?fit=144%2C207&amp;ssl=1\" class=\"wp-image-315 aligncenter\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/dossier_enco.jpg?resize=32%2C46&#038;ssl=1\" alt=\"dossier_enco\" width=\"32\" height=\"46\" \/><\/a><\/td>\n<td style=\"width: 85.5952%; height: 23px;\">Correction sur des coordonn\u00e9es apparentes (<strong><a href=\"https:\/\/voyager3.com\/wp-content\/uploads\/2015\/10\/Corrections_coordonn\u00e9es_apparentes.pdf\">pdf<\/a><\/strong> )<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<ul>\n<li>Conclusion<\/li>\n<\/ul>\n<table  class=\" table table-hover\" >\n<tbody>\n<tr>\n<td><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"321\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=321\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Enco_monture.jpg?fit=383%2C483&amp;ssl=1\" data-orig-size=\"383,483\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"Enco_monture\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Enco_monture.jpg?fit=383%2C483&amp;ssl=1\" class=\"alignleft wp-image-321 \" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Enco_monture.jpg?resize=173%2C219&#038;ssl=1\" alt=\"Enco_monture\" width=\"173\" height=\"219\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Enco_monture.jpg?resize=237%2C300&amp;ssl=1 237w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Enco_monture.jpg?w=383&amp;ssl=1 383w\" sizes=\"auto, (max-width: 173px) 100vw, 173px\" \/><\/td>\n<td><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"317\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=317\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Obs_Severac_De_nuit.jpg?fit=1037%2C691&amp;ssl=1\" data-orig-size=\"1037,691\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"Obs_Severac_De_nuit\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Obs_Severac_De_nuit.jpg?fit=648%2C432&amp;ssl=1\" class=\"alignright wp-image-317 \" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Obs_Severac_De_nuit.jpg?resize=223%2C148&#038;ssl=1\" alt=\"Obs_Severac_De_nuit\" width=\"223\" height=\"148\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Obs_Severac_De_nuit.jpg?resize=300%2C199&amp;ssl=1 300w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Obs_Severac_De_nuit.jpg?resize=1024%2C682&amp;ssl=1 1024w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Obs_Severac_De_nuit.jpg?resize=750%2C500&amp;ssl=1 750w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2014\/06\/Obs_Severac_De_nuit.jpg?w=1037&amp;ssl=1 1037w\" sizes=\"auto, (max-width: 223px) 100vw, 223px\" \/><\/td>\n<td>\n<p>Ca marche !<\/p>\n<p>A nous les petites \u00e9toiles !<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><strong>R\u00e9alisation et mise en place<\/strong><\/p>\n<table  class=\" table table-hover\" style=\"border-collapse: collapse; width: 100%;\">\n<tbody>\n<tr>\n<td style=\"width: 100%;\"><strong><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2015\/05\/IMG_4811_web.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"1110\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=1110\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2015\/05\/IMG_4811_web.jpg?fit=1920%2C1280&amp;ssl=1\" data-orig-size=\"1920,1280\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;3.5&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;Canon EOS 350D DIGITAL&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;1310172042&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;22&quot;,&quot;iso&quot;:&quot;400&quot;,&quot;shutter_speed&quot;:&quot;0.016666666666667&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;1&quot;}\" data-image-title=\"IMG_4811_web\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2015\/05\/IMG_4811_web.jpg?fit=648%2C432&amp;ssl=1\" class=\"aligncenter size-medium wp-image-1110\" src=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2015\/05\/IMG_4811_web.jpg?resize=300%2C200&#038;ssl=1\" alt=\"IMG_4811_web\" width=\"300\" height=\"200\" srcset=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2015\/05\/IMG_4811_web.jpg?resize=300%2C200&amp;ssl=1 300w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2015\/05\/IMG_4811_web.jpg?resize=1024%2C683&amp;ssl=1 1024w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2015\/05\/IMG_4811_web.jpg?resize=750%2C500&amp;ssl=1 750w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2015\/05\/IMG_4811_web.jpg?w=1920&amp;ssl=1 1920w, https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2015\/05\/IMG_4811_web.jpg?w=1296&amp;ssl=1 1296w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><\/strong><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 100%;\"><strong><a href=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2015\/05\/IMG_4507_web.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"1097\" data-permalink=\"https:\/\/voyager3.com\/?attachment_id=1097\" data-orig-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2015\/05\/IMG_4507_web.jpg?fit=1920%2C1280&amp;ssl=1\" data-orig-size=\"1920,1280\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;4&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;Canon EOS 350D DIGITAL&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;1290121184&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;24&quot;,&quot;iso&quot;:&quot;400&quot;,&quot;shutter_speed&quot;:&quot;0.016666666666667&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;1&quot;}\" data-image-title=\"IMG_4507_web\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/voyager3.com\/wp-content\/uploads\/2015\/05\/IMG_4507_web.jpg?fit=648%2C432&amp;ssl=1\" 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