Manipulator + mobile robot joint error


I’m trying to import and run my own robot, mobile manipulator.

However, I’ve faced to some problems like these errors below.

  1. Moving like zero gravity even if it has physics.

  1. Manipulator links do not work well.

Is there any example related to control of mobile manipulator ?

If not, how can I fix these problems ?

Thank you !

Hello @swimpark,

Some things to watch out for:

  1. Inspect the physics mass properties for the links (mass, Inertia tensor), and check if they are in the expected range. Inertia tensors that are too big will cause the “no gravity” feeling.
  2. When composing the mobile base, ensure that there are no nested rigid bodies, as that is an illegal composition
  3. Make sure there is only one Articulation Root, as the physics API does not allow nested articulations roots
  4. Make sure there are no loops in the articulation by inspecting the joints, and the bodies they connect. A joint hierarchy is considered a loop when Body A can reach itself without reusing any joint in the articulation. For example, B1J1B2J2B3J3B1
  5. Check the joint drives for Damping/Stiffness properties. on a Position drive, Stiffness must be greater than zero, and it’s recommended to have at least a minimal Damping, to avoid oscillations. For velocity drives, Stiffness must be zero, and Damping must be sufficient to drive the bodies the joint is connected to.

if you are unable to find a solution with those tips and are willing to share the asset, we can take a look to see what’s going on.