{"action":"opened","issue":{"url":"https://api.github.com/repos/ev3dev/ev3dev/issues/1067","repository_url":"https://api.github.com/repos/ev3dev/ev3dev","labels_url":"https://api.github.com/repos/ev3dev/ev3dev/issues/1067/labels{/name}","comments_url":"https://api.github.com/repos/ev3dev/ev3dev/issues/1067/comments","events_url":"https://api.github.com/repos/ev3dev/ev3dev/issues/1067/events","html_url":"https://github.com/ev3dev/ev3dev/issues/1067","id":312054927,"number":1067,"title":"Large Motor reverses after rotation","user":{"login":"worgarside","id":26073454,"avatar_url":"https://avatars2.githubusercontent.com/u/26073454?v=4","gravatar_id":"","url":"https://api.github.com/users/worgarside","html_url":"https://github.com/worgarside","followers_url":"https://api.github.com/users/worgarside/followers","following_url":"https://api.github.com/users/worgarside/following{/other_user}","gists_url":"https://api.github.com/users/worgarside/gists{/gist_id}","starred_url":"https://api.github.com/users/worgarside/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/worgarside/subscriptions","organizations_url":"https://api.github.com/users/worgarside/orgs","repos_url":"https://api.github.com/users/worgarside/repos","events_url":"https://api.github.com/users/worgarside/events{/privacy}","received_events_url":"https://api.github.com/users/worgarside/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":0,"created_at":"2018-04-06T17:25:06Z","updated_at":"2018-04-06T17:25:06Z","closed_at":null,"author_association":"NONE","body":"I'm trying to get a motor to rotate accurately to 45 degree increments, up to 48 times in a row. After each rotation, the motor reverses by a couple of degrees and by the end of the loop, it's clearly out of line. I've tried several routes, such as adding a `ramp_down_sp` to slow down the end, or using `run_to_abs_pos` instead of relative, but to no avail. If I rotate the entire amount at once, the motor is perfectly aligned by the end, so it's a problem with a small overhead per rotation.\r\n\r\nI'm using Python 3.6, with the latest version of ev3dev. This is for my dissertation so any help would be greatly appreciated!\r\n\r\nI've uploaded a [video to demonstrate the issue here](https://youtu.be/IEwG2lL-Dww), and the code used in it is below. Thanks in advance!\r\n\r\n```\r\nfrom time import sleep\r\nfrom ev3dev.ev3 import Sound, OUTPUT_A\r\nfrom ev3dev.helper import LargeMotor\r\n\r\nmotor = LargeMotor(OUTPUT_A)\r\nmotor.stop_action = 'hold'\r\n\r\nfor i in range(16):\r\n    motor.run_to_rel_pos(position_sp=200, speed_sp=510)\r\n    motor.wait_until_not_moving()\r\n    sleep(0.05)\r\n    Sound.beep()\r\n```"}}
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