ROS_DifferentialBase - Errors

I am successfully test creating differential robot in Omniverse Isaac Sim. It runs okay when target velocity is applied. But when I add ROSDifferentialBase component I get the following errors on the terminal window.

2021-07-21 06:11:20 [7,993,421ms] [Error] [omni.isaac.dynamic_control.plugin] DcGetRigidBodyAngularVelocity: Invalid or expired body handle
2021-07-21 06:11:20 [7,993,429ms] [Error] [omni.isaac.dynamic_control.plugin] DcGetRigidBodyPose: Invalid or expired body handle
2021-07-21 06:11:20 [7,993,429ms] [Error] [omni.isaac.dynamic_control.plugin] DcGetRigidBodyPose: Invalid or expired body handle
2021-07-21 06:11:20 [7,993,429ms] [Error] [omni.isaac.dynamic_control.plugin] DcGetRigidBodyLinearVelocity: Invalid or expired body handle
2021-07-21 06:11:20 [7,993,429ms] [Error] [omni.isaac.dynamic_control.plugin] DcGetRigidBodyAngularVelocity: Invalid or expired body handle

I am not sure what I need to do to make it work in this simple custom robot (base + L and R wheels). It works fine with the Carter_ROS example. I tried to replicate it but not successful yet.

Any help/suggestions will be appreciated it.

Thanks.

Here is more information to understand my misunderstanding:

Error when trying to create ROS DifferentialBase.

2021-07-21 08:41:40 [2,706,460ms] [Warning] [omni.isaac.dynamic_control.plugin] DcPeekObjectType: Function called while not simulating
2021-07-21 08:41:40 [2,706,460ms] [Error] [omni.isaac.ros_bridge.plugin] chassisPrim is not a valid articulation

Thanks.

Hi,

A little question: Is your chassisPrim (which must be defined by clicking on the Add Target button inside Raw USD Properties, if you are using the graphical interface) an Articulation Root?

Can you share screenshots of your stage and prim properties?

Like toni said, you need to make sure the prim specified in the chassisPrim property for the ROS Differential Base component has an Articulation Root, which you can see in the property panel.


image