Gazebo | Ignition | Community
Ask Your Question

Frictionless sphere stops spinning for smaller torques

asked 2023-02-27 12:04:07 -0500

Patoinso gravatar image


I'm experimenting with Gazebo Classic v11.10.2 and friction coefficient. I added a unit sphere, set the mass to 120kg, and the mu1 and mu2 coefficient to 0.0. Then I apply a small torque (eg. <500 N.m) around the X axis through the GUI "Aply Force/Torque" According to the GUI plot, I can see the torque is applied during 1s.

The sphere moves slightly during about 1s then stop (I can observe this by plotting the position or the speed in the GUI). As I set the friction coef to 0.0, I expected the sphere to spin endlessly, without translating. However, if I applied a high torque (5000 N.m), the sphere spins endlessly at constant speed.

Why is the frictionless sphere stopping for small torques ? Thanks

edit retag flag offensive close merge delete

1 Answer

Sort by ยป oldest newest most voted

answered 2023-02-27 21:07:00 -0500

Veerachart gravatar image

It's because of this allow_auto_disable parameter. When the model's speed is smaller than the threshold value for a while, the physics update for that model will be disabled. It takes some force and time to enable the model back again. By default, it's set to true. If you want the sphere to rotate forever, set this to false in the sdf.

I think the minimum speed and time can be set through the code, not in the sdf. You can also enable/disable the model from the code as well (via world plugin or model plugin, for example.)

edit flag offensive delete link more
Login/Signup to Answer

Question Tools

1 follower


Asked: 2023-02-27 12:04:07 -0500

Seen: 90 times

Last updated: Feb 27