How to deal with limit tag when joint limits are changeable (depended on other links) and not fixed?

asked 2017-01-10 04:43:03 -0500

jake123
23 ●2 ●5 ●6

updated 2017-01-11 02:59:22 -0500

My robot has not fixed joint limits. On every position is has a different joint limits other side it will hit parent/child link. Or it will go out of working area because I removed support links (closed loop) that are increasing max payload. What I think is to add an extra dummy link to parent/child link to make collision detection and prevent crashing. But i can't deal when it is going out of working area. Can I add a mathematic equation on limits?

If not I should add again support links (counterweights for payload), close the open loop, prevent collision with parent links and then it will never go out of working area.. but i find it too difficult to close the open loop. Is there any way to deal with it?

Update1:

Question: How to make support_link_2 follow a specific point/axe on link_3

Video of the custom robot: https://2.sendvid.com/7w3a2jp5.mp4

Structure:

Structure

answered 2017-01-10 07:27:43 -0500

gvdhoorn
86574 ●283 ●1432 ●1054 http://cor.tudelft.nl/

I can write a more extensive answer later, but for now: no, there is no support for festooning joint limits anywhere in ROS. Not in URDF, SDF or any consumers of those formats (joint_state_publisher, robot_state_publisher or Gazebo). MoveIt! does also not support this.

The big assumption in almost everything that deals with robot kinematics and geometry is that the structure is defined once, loaded at application startup and does not change.

Perhaps if you can describe your robot better (diagram or picture), we can suggest alternatives / work-arounds.