Simulation of two simple robot arms to grasp a ring using SimMechanics contact forces library block

I want to implement a simulation of two robot arms grasping a movable ring. Now I have modeled the contact force using SimMechanics contact forces library--Circle to Ring contact. The contact between one hand and the ring is simplified as three little circles (radius = 0.0001m) contacting with the ring (two circles inside the ring and one circle outside). However, the hands always penetrate the ring, and cannot grasp the ring. So can somebody help me with this problem? I want to know whether my modeling method is correct or not.

Answer 1

[Steve Miller]

Hi Yuhan,

This looks like a 3D problem, so you should probably be using Sphere-to-Cylinder, not Circle-to-Ring.

Circle-to-Ring will only work if your hands and the ring are constrained to the same plane. Make sure the frames attached to Circle-to-Ring are properly oriented (see the documentation).

The other thing to watch out for is make sure your spheres are appropriately sized. 1e-4m radius is pretty small. That can work, but your simulation step size will also need to be small so that the spheres do not pass through the cylinder on a single time step.

Thanks,

-Steve