{"action":"created","issue":{"url":"https://api.github.com/repos/iNavFlight/inav/issues/564","repository_url":"https://api.github.com/repos/iNavFlight/inav","labels_url":"https://api.github.com/repos/iNavFlight/inav/issues/564/labels{/name}","comments_url":"https://api.github.com/repos/iNavFlight/inav/issues/564/comments","events_url":"https://api.github.com/repos/iNavFlight/inav/issues/564/events","html_url":"https://github.com/iNavFlight/inav/issues/564","id":175039247,"number":564,"title":"Fixed wing PID controller improvement","user":{"login":"digitalentity","id":11059099,"avatar_url":"https://avatars.githubusercontent.com/u/11059099?v=3","gravatar_id":"","url":"https://api.github.com/users/digitalentity","html_url":"https://github.com/digitalentity","followers_url":"https://api.github.com/users/digitalentity/followers","following_url":"https://api.github.com/users/digitalentity/following{/other_user}","gists_url":"https://api.github.com/users/digitalentity/gists{/gist_id}","starred_url":"https://api.github.com/users/digitalentity/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/digitalentity/subscriptions","organizations_url":"https://api.github.com/users/digitalentity/orgs","repos_url":"https://api.github.com/users/digitalentity/repos","events_url":"https://api.github.com/users/digitalentity/events{/privacy}","received_events_url":"https://api.github.com/users/digitalentity/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/iNavFlight/inav/labels/Discussion","name":"Discussion","color":"cc317c"},{"url":"https://api.github.com/repos/iNavFlight/inav/labels/Experimental","name":"Experimental","color":"1d76db"}],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":{"url":"https://api.github.com/repos/iNavFlight/inav/milestones/6","html_url":"https://github.com/iNavFlight/inav/milestones/1.3","labels_url":"https://api.github.com/repos/iNavFlight/inav/milestones/6/labels","id":1757669,"number":6,"title":"1.3","description":null,"creator":{"login":"DzikuVx","id":966811,"avatar_url":"https://avatars.githubusercontent.com/u/966811?v=3","gravatar_id":"","url":"https://api.github.com/users/DzikuVx","html_url":"https://github.com/DzikuVx","followers_url":"https://api.github.com/users/DzikuVx/followers","following_url":"https://api.github.com/users/DzikuVx/following{/other_user}","gists_url":"https://api.github.com/users/DzikuVx/gists{/gist_id}","starred_url":"https://api.github.com/users/DzikuVx/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/DzikuVx/subscriptions","organizations_url":"https://api.github.com/users/DzikuVx/orgs","repos_url":"https://api.github.com/users/DzikuVx/repos","events_url":"https://api.github.com/users/DzikuVx/events{/privacy}","received_events_url":"https://api.github.com/users/DzikuVx/received_events","type":"User","site_admin":false},"open_issues":67,"closed_issues":32,"state":"open","created_at":"2016-05-10T12:24:14Z","updated_at":"2016-09-27T07:56:02Z","due_on":null,"closed_at":null},"comments":15,"created_at":"2016-09-05T10:10:59Z","updated_at":"2016-09-28T09:05:44Z","closed_at":null,"body":"I think we have a significant issue with airplane code that affects takeoff behavior.\r\nAt the moment we have full effects of PID integrator right after arming, but this is not desired at takeoff:\r\n\r\nAt low speeds (initial acceleration) control surfaces don't have full effect on UAV stabilisation, PID control attempts to compensate using I-term. By the moment airplane have gained significant velocity for control surfaces to work reasonably good, I-term has seriously winded up and PID controller will overshoot leading to severe oscillation which might lead to a crash because altitude during takeoff might be too low to allow successful recovery. This is precisely what happened to my Ranger airplane during maiden with stabilisation.\r\n\r\nI suggest creating a TAKEOFF mode that will detect a launch (a jerk in acceleration) and disable I-term in PID control until airplane gains some velocity (using GPS, airspeed sensor or a simple timer). During takeoff only P-term will be active - aircraft might not be able to maintain attitude precisely but in general it should be more stable during takeoff.\r\n\r\nFW flyers, thougts?\r\n\r\nIdeas and implementations:\r\n\r\n- [x] I-term limiting for fixed wing (#574)\r\n- [ ] Take off detection by timer\r\n- [ ] Take off detection by accelerator\r\n- [ ] Prevent some functions to engage before take-off is detected"},"comment":{"url":"https://api.github.com/repos/iNavFlight/inav/issues/comments/250112531","html_url":"https://github.com/iNavFlight/inav/issues/564#issuecomment-250112531","issue_url":"https://api.github.com/repos/iNavFlight/inav/issues/564","id":250112531,"user":{"login":"sppnk","id":12456418,"avatar_url":"https://avatars.githubusercontent.com/u/12456418?v=3","gravatar_id":"","url":"https://api.github.com/users/sppnk","html_url":"https://github.com/sppnk","followers_url":"https://api.github.com/users/sppnk/followers","following_url":"https://api.github.com/users/sppnk/following{/other_user}","gists_url":"https://api.github.com/users/sppnk/gists{/gist_id}","starred_url":"https://api.github.com/users/sppnk/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/sppnk/subscriptions","organizations_url":"https://api.github.com/users/sppnk/orgs","repos_url":"https://api.github.com/users/sppnk/repos","events_url":"https://api.github.com/users/sppnk/events{/privacy}","received_events_url":"https://api.github.com/users/sppnk/received_events","type":"User","site_admin":false},"created_at":"2016-09-28T09:05:44Z","updated_at":"2016-09-28T09:05:44Z","body":"How will this detection affect to bungee-cord launching (no throttle)? I amd flying lately a Mini Talon, wich I launch by bungee cord."}}
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