{"action":"created","issue":{"url":"https://api.github.com/repos/parallaxinc/Flight-Controller/issues/13","repository_url":"https://api.github.com/repos/parallaxinc/Flight-Controller","labels_url":"https://api.github.com/repos/parallaxinc/Flight-Controller/issues/13/labels{/name}","comments_url":"https://api.github.com/repos/parallaxinc/Flight-Controller/issues/13/comments","events_url":"https://api.github.com/repos/parallaxinc/Flight-Controller/issues/13/events","html_url":"https://github.com/parallaxinc/Flight-Controller/issues/13","id":170033747,"number":13,"title":"Altitude Hold with Laser Rangefinder Feedback Loop","user":{"login":"RoboTechie","id":13735732,"avatar_url":"https://avatars.githubusercontent.com/u/13735732?v=3","gravatar_id":"","url":"https://api.github.com/users/RoboTechie","html_url":"https://github.com/RoboTechie","followers_url":"https://api.github.com/users/RoboTechie/followers","following_url":"https://api.github.com/users/RoboTechie/following{/other_user}","gists_url":"https://api.github.com/users/RoboTechie/gists{/gist_id}","starred_url":"https://api.github.com/users/RoboTechie/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/RoboTechie/subscriptions","organizations_url":"https://api.github.com/users/RoboTechie/orgs","repos_url":"https://api.github.com/users/RoboTechie/repos","events_url":"https://api.github.com/users/RoboTechie/events{/privacy}","received_events_url":"https://api.github.com/users/RoboTechie/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/parallaxinc/Flight-Controller/labels/bug","name":"bug","color":"fc2929"}],"state":"closed","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":1,"created_at":"2016-08-08T21:48:26Z","updated_at":"2016-09-17T04:13:22Z","closed_at":"2016-09-17T04:13:22Z","body":"I tested the most recent firmware release today, and while the barometric pressure and PING))) altitude hold modes perform well, using the SF11/C Laser Rangefinder causes an oscillatory feedback \"loop\", whereby as soon as the laser-assisted altitude hold is enable, the ELEV-8 begins to oscillate vertically (moves down vertically, then back up, then back down), and the magnitude of the oscillations (distance up/dwn) quickly increases with time.\r\n\r\nI had wireless telemetry set up during the tests. Here is the graph of distance to ground over time, showing the oscillations\r\n![osc1](https://cloud.githubusercontent.com/assets/13735732/17497340/41a30cc6-5d76-11e6-96ec-c8f2e99a0799.png)\r\n\r\nI then tried changing the Altitude PID from 125 to 70, thinking that maybe the value was just to aggressive, but it didn't have any noticeable effect:\r\n![laser2](https://cloud.githubusercontent.com/assets/13735732/17497494/fa53d926-5d76-11e6-8b2f-765537e61646.png)\r\n\r\nIf I had to guess, I would think that a sign is reversed somewhere."},"comment":{"url":"https://api.github.com/repos/parallaxinc/Flight-Controller/issues/comments/247747901","html_url":"https://github.com/parallaxinc/Flight-Controller/issues/13#issuecomment-247747901","issue_url":"https://api.github.com/repos/parallaxinc/Flight-Controller/issues/13","id":247747901,"user":{"login":"MatzElectronics","id":19737272,"avatar_url":"https://avatars.githubusercontent.com/u/19737272?v=3","gravatar_id":"","url":"https://api.github.com/users/MatzElectronics","html_url":"https://github.com/MatzElectronics","followers_url":"https://api.github.com/users/MatzElectronics/followers","following_url":"https://api.github.com/users/MatzElectronics/following{/other_user}","gists_url":"https://api.github.com/users/MatzElectronics/gists{/gist_id}","starred_url":"https://api.github.com/users/MatzElectronics/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/MatzElectronics/subscriptions","organizations_url":"https://api.github.com/users/MatzElectronics/orgs","repos_url":"https://api.github.com/users/MatzElectronics/repos","events_url":"https://api.github.com/users/MatzElectronics/events{/privacy}","received_events_url":"https://api.github.com/users/MatzElectronics/received_events","type":"User","site_admin":false},"created_at":"2016-09-17T04:13:22Z","updated_at":"2016-09-17T04:13:22Z","body":"This appears to be solved by removing the filtering on the SF-11C, which is turned on by default.  @RoboTechie has drafted instructions"}}
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