{"action":"created","issue":{"url":"https://api.github.com/repos/ros-industrial/ur_modern_driver/issues/183","repository_url":"https://api.github.com/repos/ros-industrial/ur_modern_driver","labels_url":"https://api.github.com/repos/ros-industrial/ur_modern_driver/issues/183/labels{/name}","comments_url":"https://api.github.com/repos/ros-industrial/ur_modern_driver/issues/183/comments","events_url":"https://api.github.com/repos/ros-industrial/ur_modern_driver/issues/183/events","html_url":"https://github.com/ros-industrial/ur_modern_driver/pull/183","id":339923203,"node_id":"MDExOlB1bGxSZXF1ZXN0MjAwNDU4NjQ5","number":183,"title":"Set speedj_time from the parameter server","user":{"login":"megantuttle","id":16921298,"node_id":"MDQ6VXNlcjE2OTIxMjk4","avatar_url":"https://avatars2.githubusercontent.com/u/16921298?v=4","gravatar_id":"","url":"https://api.github.com/users/megantuttle","html_url":"https://github.com/megantuttle","followers_url":"https://api.github.com/users/megantuttle/followers","following_url":"https://api.github.com/users/megantuttle/following{/other_user}","gists_url":"https://api.github.com/users/megantuttle/gists{/gist_id}","starred_url":"https://api.github.com/users/megantuttle/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/megantuttle/subscriptions","organizations_url":"https://api.github.com/users/megantuttle/orgs","repos_url":"https://api.github.com/users/megantuttle/repos","events_url":"https://api.github.com/users/megantuttle/events{/privacy}","received_events_url":"https://api.github.com/users/megantuttle/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":2,"created_at":"2018-07-10T16:43:44Z","updated_at":"2018-11-09T17:53:11Z","closed_at":null,"author_association":"NONE","pull_request":{"url":"https://api.github.com/repos/ros-industrial/ur_modern_driver/pulls/183","html_url":"https://github.com/ros-industrial/ur_modern_driver/pull/183","diff_url":"https://github.com/ros-industrial/ur_modern_driver/pull/183.diff","patch_url":"https://github.com/ros-industrial/ur_modern_driver/pull/183.patch"},"body":"When using the velocity-based controller, we were experiencing stuttering/jerky movements on our UR3.  After some investigating, I determined that this behavior was caused by the time parameter in the speedj() command, which was set too low for our setup (UR3 v.3.5, Kinetic, Ubuntu 16.04). I found that commands were not being received fast enough so stop commands were periodically issued, resulting in random stuttering/jerky movements.  The issue was fixed by increasing the time parameter, so the purpose of this PR is to add the speedj_time parameter to the parameter server so it can be easily adjusted (similar to the servoj_time parameter).\r\n\r\nFrom the [UR scripting manual](https://www.universal-robots.com/download/) v3.3: \r\n> **speedj** (qd, a, t_min)\r\n> Accelerate linearly in joint space and continue with constant joint\r\nspeed. The time t is optional; if provided the function will return after\r\ntime t, regardless of the target speed has been reached. If the time t is\r\nnot provided, the function will return when the target speed is reached\r\n> \r\n> **Parameters**\r\n> * qd: joint speeds [rad/s]\r\n> * a: joint acceleration [rad/sˆ2] (of leading axis)\r\n> * t_min: time [s] before the function returns (optional)\r\n"},"comment":{"url":"https://api.github.com/repos/ros-industrial/ur_modern_driver/issues/comments/437440865","html_url":"https://github.com/ros-industrial/ur_modern_driver/pull/183#issuecomment-437440865","issue_url":"https://api.github.com/repos/ros-industrial/ur_modern_driver/issues/183","id":437440865,"node_id":"MDEyOklzc3VlQ29tbWVudDQzNzQ0MDg2NQ==","user":{"login":"megantuttle","id":16921298,"node_id":"MDQ6VXNlcjE2OTIxMjk4","avatar_url":"https://avatars2.githubusercontent.com/u/16921298?v=4","gravatar_id":"","url":"https://api.github.com/users/megantuttle","html_url":"https://github.com/megantuttle","followers_url":"https://api.github.com/users/megantuttle/followers","following_url":"https://api.github.com/users/megantuttle/following{/other_user}","gists_url":"https://api.github.com/users/megantuttle/gists{/gist_id}","starred_url":"https://api.github.com/users/megantuttle/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/megantuttle/subscriptions","organizations_url":"https://api.github.com/users/megantuttle/orgs","repos_url":"https://api.github.com/users/megantuttle/repos","events_url":"https://api.github.com/users/megantuttle/events{/privacy}","received_events_url":"https://api.github.com/users/megantuttle/received_events","type":"User","site_admin":false},"created_at":"2018-11-09T17:53:11Z","updated_at":"2018-11-09T17:53:11Z","author_association":"NONE","body":"I was hesitant to apply the change to all PolyScope versions originally because I've only used v3.3 and up but I should have just looked at the other script manuals. I'll add it to the previous versions. Is there a reason that the driver doesn't set the time parameter for v3.1 and v3.2?\r\n\r\nI see what you mean about being wary of setting default values in the launch files since it depends on the PolyScope version, but do we really want to make everyone set a speedj_time parameter? If the default is set to 20ms I don't think it would negatively affect anyone's current setup. If the default is set to 8ms it might cause some stuttering on the early versions, but even at top speed, the difference in travel distance between 20ms and 8ms would be very small."}}
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