Attaching objects to Gripper does not work in effect.

Issue #2114 new
Yuki Furuta
created an issue

Current grasp checking algorithm for gripper is:

  • check contacts between objects and gripper links on every updates (update rate is 0.75 sec [1])
  • if contacts exists continuously (attach_steps parameter is used), it starts to compute distance of every contacts. [2]
  • Latest 10 differences from the distance of contacts and one on previous time is collected. [3] (Gripper::HandleAttach)
  • If none of these differences and their variance exceeds threshold 1e-5, then the object are attached to the gripper link. [4]

The problem is there is hard-coded parameter 10 for computing a maximum of the latest differences of collision distances, which means we must call method Gripper::HandleAttach at least 10 times for regarding that objects should be attached to the gripper. As the update rate for grippers are not so high, method Gripper::HandleAttach may not be called 10 times on grasp action. So it should be better to provide option to change update rate for gripper and the hard-coded parameter 10. This may need to change the specification of sdformat. How do you think about it? And how can we change?

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