Followtarget - How to rotate my robot?

Omniverse Isaac Sim
1

Hi, I want to rotate my robot 90 degrees with the up-axis.
I expected that the robot would still work properly, but It seems there is a frame mismatch.

    def set_robot(self) -> None:
        
        gripper = ParallelGripper(
            end_effector_prim_path="/World/ur5e_gripper/robotiq_85_left_finger_tip_link",
            joint_prim_names=["robotiq_85_left_finger_tip_joint", "robotiq_85_right_finger_tip_joint"],
            joint_opened_positions=np.array([0.1, 0.1]),
            joint_closed_positions=np.array([0.0, 0.0]),
            action_deltas=np.array([0.25, 0.25]))
        
        manipulator = SingleManipulator(prim_path="/World/ur5e_gripper",
                                        name="ur5e",
                                        end_effector_prim_name="End_Effector",
                                        gripper=gripper,
                                        position=np.array([0, 0, 0]), 
                                        orientation=np.array([0.7071068, 0, 0, 0.7071068]))  # Here I changed!
        joints_default_positions = np.zeros(12)
        manipulator.set_joints_default_state(positions=joints_default_positions)
        return manipulator

I would appreciate it if you give me some advice which is the simplest & best way to handle this.

2

Hi @PARKBONG -
The issue you’re experiencing might be due to the way you’re setting the orientation of the robot. In your code, you’re setting the orientation as a quaternion. Quaternions are a way to perform 3D rotations and are defined by four numbers [x, y, z, w].

The quaternion you’re using [0.7071068, 0, 0, 0.7071068] corresponds to a rotation of 90 degrees around the x-axis. If you want to rotate the robot around the up-axis (which is usually the z-axis), you would need to use a different quaternion.

For a 90 degrees rotation around the z-axis, you can use the quaternion [0, 0, 0.7071068, 0.7071068].

So, you should change the orientation line in your code to:

orientation=np.array([0, 0, 0.7071068, 0.7071068])  # Here I changed!

Please note that the exact axis might depend on the coordinate system used in your specific setup. If the up-axis is not the z-axis in your case, you might need to adjust the quaternion accordingly.

3

Can you share the whole code?

4

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