{"action":"created","issue":{"url":"https://api.github.com/repos/ethz-asl/rovio/issues/23","labels_url":"https://api.github.com/repos/ethz-asl/rovio/issues/23/labels{/name}","comments_url":"https://api.github.com/repos/ethz-asl/rovio/issues/23/comments","events_url":"https://api.github.com/repos/ethz-asl/rovio/issues/23/events","html_url":"https://github.com/ethz-asl/rovio/issues/23","id":117786971,"number":23,"title":"Position in inertial-z (altitude) seems to drift","user":{"login":"devbharat","id":3105122,"avatar_url":"https://avatars.githubusercontent.com/u/3105122?v=3","gravatar_id":"","url":"https://api.github.com/users/devbharat","html_url":"https://github.com/devbharat","followers_url":"https://api.github.com/users/devbharat/followers","following_url":"https://api.github.com/users/devbharat/following{/other_user}","gists_url":"https://api.github.com/users/devbharat/gists{/gist_id}","starred_url":"https://api.github.com/users/devbharat/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/devbharat/subscriptions","organizations_url":"https://api.github.com/users/devbharat/orgs","repos_url":"https://api.github.com/users/devbharat/repos","events_url":"https://api.github.com/users/devbharat/events{/privacy}","received_events_url":"https://api.github.com/users/devbharat/received_events","type":"User","site_admin":false},"labels":[],"state":"closed","locked":false,"assignee":null,"milestone":null,"comments":3,"created_at":"2015-11-19T10:42:54Z","updated_at":"2015-11-26T12:38:48Z","closed_at":"2015-11-26T12:38:48Z","body":"When executing vertical motion with the camera facing down, rovio's z estimate seems to drift with respect to gazebo's ground truth with time. It happens more severely when the vertical motion is executed slowly (the slower the worse) and better when accelerations are higher.\r\n\r\nI can observe on the Rviz output, that when rising slowly, rather than moving the IMU-Camera position estimate in the upword direction, it adjusts the tracked feature patch's location (then all start condensing closer). This doesn't happen when the vertical accelerations are higher.\r\n\r\nPlots below:\r\nSlow vertical motion:\r\n![vel_test_z_slow_3d](https://cloud.githubusercontent.com/assets/3105122/11268708/92c5138a-8eb2-11e5-9092-f569f9cc7628.png)\r\n![vel_test_z_slow_position](https://cloud.githubusercontent.com/assets/3105122/11268710/98af3c6c-8eb2-11e5-95ea-b49990ead3ee.png)\r\n![vel_test_z_slow_linear_velocity](https://cloud.githubusercontent.com/assets/3105122/11268711/9afe86d0-8eb2-11e5-8ba3-95f51749b0ff.png)\r\n\r\nFast vertical motion:\r\n![vel_test_z_3d](https://cloud.githubusercontent.com/assets/3105122/11268721/a41151c6-8eb2-11e5-9eca-7c28761d8351.png)\r\n![vel_test_z_position](https://cloud.githubusercontent.com/assets/3105122/11268722/a7895722-8eb2-11e5-827f-d171788df411.png)\r\n![vel_test_z_linear_velocity](https://cloud.githubusercontent.com/assets/3105122/11268725/aa3944a0-8eb2-11e5-96e5-326fec3104fa.png)\r\n\r\nThe datasets were collected with gazebo simulator, px4 sitl, and rovio position feedback."},"comment":{"url":"https://api.github.com/repos/ethz-asl/rovio/issues/comments/159902309","html_url":"https://github.com/ethz-asl/rovio/issues/23#issuecomment-159902309","issue_url":"https://api.github.com/repos/ethz-asl/rovio/issues/23","id":159902309,"user":{"login":"devbharat","id":3105122,"avatar_url":"https://avatars.githubusercontent.com/u/3105122?v=3","gravatar_id":"","url":"https://api.github.com/users/devbharat","html_url":"https://github.com/devbharat","followers_url":"https://api.github.com/users/devbharat/followers","following_url":"https://api.github.com/users/devbharat/following{/other_user}","gists_url":"https://api.github.com/users/devbharat/gists{/gist_id}","starred_url":"https://api.github.com/users/devbharat/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/devbharat/subscriptions","organizations_url":"https://api.github.com/users/devbharat/orgs","repos_url":"https://api.github.com/users/devbharat/repos","events_url":"https://api.github.com/users/devbharat/events{/privacy}","received_events_url":"https://api.github.com/users/devbharat/received_events","type":"User","site_admin":false},"created_at":"2015-11-26T12:38:48Z","updated_at":"2015-11-26T12:38:48Z","body":"This does not happen anymore as of commit b1fd00886b731 . "}}