Add a static collison mesh to robot

Omniverse Isaac Sim
1

Hello there

I am trying to add a the mesh of a robot to Kaya robot, to allow for holonomic movement. This robot has the purpose of carrying cargo. The problem: If I add a collision preset to the mesh, it can successfully collide with the cargo but this collision moves the entire robot. Is it possible to establish a collision box as a reference to the base_link without interfering with the remaining robot mesh. Sorry if the message is confusing.

As you can see in the video the entire robot moved despite the collision only occurred in the mesh I added, I realize by adding the mesh to Kaya it change its composition, but is my goal not possible?

3

Hi @ph.silva1, thank you for your question and sorry for the delay. I am not 100% sure what behavior you are looking for. From what I understand, you want to make the cargo (gray cube) be able to collide with the chassis of the robot you added, but you don’t want this collision to affect the Kaya robot that part of the same prim tree. If that is correct, you can try a couple of things:

  1. Increase the weight of the robot itself (either the chassis or the Kaya). Large inertia might be more reflective of a real setup anyways, and a box colliding will have less of a tilting effect due to the robot inertia.
  2. Add a revolute joint (prismatic might also do it) with passive stiffness and damping so that the impact. You can do that by adding a joint between the chassis part and the base_link. Then you right click on the joint and add a Drive component: Add>Physics>Angular Drive. Then set the parameters that works for you.

Hope that helps,
Michael

4

Just to make it clear, I want to apply the mesh of my custom robot to the Kaya robot to simulate that the custom robot is enabled with holonomic movement without having to reconfigure the wheels, and all the other parameters. So I just want to establish a static displacement, from the Kaya base_link to the mesh of my robot, in a way that appears there is no Kaya robot, and the mesh obviously follows the movement.

Besides this I also want the robot mesh to have colliders to enable it to carry cargo, but the way I setup the robot I achieve the first objective, but not the second one, since the collision between the custom robot mesh and the cargo seems to impact the movemeent of the underlying Kaya.

I am not sure if my behavior is possible, I tried your ideas but, while establishing a higher mass helped with the collision in return it hindered the Kaya movement, and adding a revolute joint simply did not work the wheels just froze.

5

Thank you for clarifying. Another thing to try is to add casters at the perimeter of the chassis. Very low friction caster wheels. You can simply add spheres and add a Spherical joints between the spheres and the main body.