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Gripper states are reversed in simulation compared to reality

Open jkaniuka opened this issue 1 year ago • 2 comments

I have been using both the real robot (xArm6) and the simulation in Gazebo and noticed there is a problem. In section 5.7(xarm_api/xarm_msgs) it says:

Proper range of the open distance is from 0 to 850. 0 is closed, 850 is fully open. 500 is used as an example. 'ret' value is 0 for success.

When we look at the SRDF (xarm6_gripper_moveit_config/config/xarm6_with_gripper.srdf) file, you can see that distance 0 indicates an open state, and distance 850 indicates a closed state.

  <group_state group="xarm_gripper" name="open">
    <joint name="drive_joint" value="0"/>
  </group_state>
  <group_state group="xarm_gripper" name="close">
    <joint name="drive_joint" value="0.85"/>
  </group_state>

This has two consequences:

  1. Simulation does not de facto imitate reality.
  2. In simulation, there is a problem with gripper control using MoveIt- errors like the one below appear, for example.

Invalid Trajectory: start point deviates from current robot state more than 0.01 joint 'drive_joint': expected: 0, current: 0.85

jkaniuka avatar Jul 13 '23 07:07 jkaniuka