6dof joint simulation problem

I am running a simulation if I use 6dof joint my simulation is so slow that it almost seems its not working. Where in the same model it I use a planar or cartesian joint keeping rest everything same the simulation works fine. what could be going wrong?

[Ridhi Bansal]

I have few more questions:

1. If i used a planar joint between an object and ground, do I get normal force?
2. Also I tried using 6DOF joint between object and world frame and contact friction block between object and ground and the object falls passing through ground block, how to i stop it from passing through ground block?

Answer 1

[Sam Chak]

@Ridhi Bansal

Most likely that the simulation ran into one of the singularities.

You must identify the singularities and don't move your joints close to them.

[Ridhi Bansal]

I have few more questions:

1. If i used a planar joint between an object and ground, do I get normal force?
2. Also I tried using 6DOF joint between object and world frame and contact friction block between object and ground and the object falls passing through ground block, how to i stop it from passing through ground block?

[Sam Chak]

Hi @Ridhi Bansal

Correct me if I'm wrong.

1. Isn't it true that if the position of the object is higher than the ground position, then there shoud be no reaction or normal force?
2. Are you able to manually insert a few conditional statements such that it does not phantomly phase through the ground? Theoretically, there should be multiple solutions for a 6DOF robot, and you should discard solutions that phase through the ground. Else, you need to solve a Constrained Problem via optimization technique such that the ground position is the constraint.

[Ridhi Bansal]

For planar joint the normal force is zero even when on the ground. Is this correct? Because this is what my simulations are showing me.

For 6dof joint the mass passes through the ground. How do you constrain it to stay on the surface and still have a normal force?