some bugs about making Spherical joint
Posted: 21 Mar 2024, 15:58
Hello,
I'm trying to create a humanoid robot in urdf and implement it in CoppeliaSim.
I realized that I can't dynamically activate the spherical joints, so I built it with 3 revolute joints, as shown in the attachment.
For the mujoco physics engine, I made it without auxiliary masses,
For the bullet physics engine, I added a secondary mass between the revolute joints.
I have a couple questions here.
1) First, for mujoco, I thought I did a good job, but like the video (human_mujoco), it freezes during simulation.
I don't see anything wrong with the dynamics(!), so I don't know what is causing the error.
2) If I use the bullet engine, I understand that I need to add a virtual link (virtual mass) between revolutes, but I have questions such as what should be the mass or inertia of that link and should it be responsive?
- Regarding the dynamic simulation rules(?), I saw that when two objects are connected, their masses should not differ by more than 10 times. However, my concern is whether adding a virtual mass that is within 10 times the mass will cause problems with dynamics and collisions.
There are my files.
https://1drv.ms/f/s!AuvU7BTQNjpWh_Vem8H ... w?e=NaRCxI
Thank you!
I'm trying to create a humanoid robot in urdf and implement it in CoppeliaSim.
I realized that I can't dynamically activate the spherical joints, so I built it with 3 revolute joints, as shown in the attachment.
For the mujoco physics engine, I made it without auxiliary masses,
For the bullet physics engine, I added a secondary mass between the revolute joints.
I have a couple questions here.
1) First, for mujoco, I thought I did a good job, but like the video (human_mujoco), it freezes during simulation.
I don't see anything wrong with the dynamics(!), so I don't know what is causing the error.
2) If I use the bullet engine, I understand that I need to add a virtual link (virtual mass) between revolutes, but I have questions such as what should be the mass or inertia of that link and should it be responsive?
- Regarding the dynamic simulation rules(?), I saw that when two objects are connected, their masses should not differ by more than 10 times. However, my concern is whether adding a virtual mass that is within 10 times the mass will cause problems with dynamics and collisions.
There are my files.
https://1drv.ms/f/s!AuvU7BTQNjpWh_Vem8H ... w?e=NaRCxI
Thank you!