PyBullet: Programmatically set joints position and limit with createMultiBody

[ycps]

Hi, I'm experimenting with randomized robot generation, but could not find a way to set joints position or limit with createMultiBody: joints seem to always be created at the center of shapes without range limits.

I understand that using URDF or the other importers is the expected way to create robots, but I don't know what is the best approach when most of the robot features should be randomized.

I searched about this, but could only find this similar questions in the PyBullet forum:

• Programmatically set the revolute (hinge) joint limits?
• how to change joint position

Thank you for Bullet!

[erwincoumans]

Joint position can be set using the linkPositions argument (and then change joint angle using resetJointState)
See this example:
https://github.com/bulletphysics/bullet3/blob/master/examples/pybullet/examples/createMultiBodyLinks.py

Joint limits are indeed not exposed yet. I think the joint limit constraints are actually added but not activated. We should implement a 'changeDynamics' method to modify the joint limits.

[erwincoumans]

Here is a CL that allows to enable/modify lower/upper joint limits and also joint limit max force.
See #2919
Note that the CL doesn't update the internal info, so the joint lower/upper limits in getJointInfo will not be updated!