Wrong parallel gripper position when gripping an object


I created the urdf of a cartesian robot with a schunk EGH gripper fixed on it:
cartesian_robot_EGH.usd (1.3 MB)
cartesian_robot_EGH.urdf (9.6 KB)

When using this gripper in Isaac Sim, the closure of the gripper does not work as expected when closing the gripper to grasp an object.
Capture d’écran 2023-05-09 à 16.34.13

Indeed, one of the tip reaches its target position but the other one does not and the gripper is not centered as it would be in reality. In the urdf, the “mimic” property is used to represent this behavior. In this issue Problem for isaacgym for mimic joint, it is said that there is no mimic property provided by default in isaacgym, is it the case in Isaac Sim now ?

To solve the problem, this issue How to implement gripper open/close action? suggests to reduce the number of dof to have X dof for the joint of the arm + a dof for the gripper (and not 2 dofs for the 2 fingers of the gripper). However, I don’t know how to implement it knowing I used the SingleManipulator class for my robot and the ParallelGripper class to control my gripper.

Does someone know how the gripper could have the good behavior ?

Hi @alempereur - Someone from our team will review and respond back to you.