How to simulate revolute joint friction?

[Patrick Roncagliolo]

I'd like to simulate a revolute joint with some kind of friction in it, like a torque proportional to bearing/radial load and opposite in sign to the current rotation direction.

However, I could not find an example for this. Is it possible to implement such behaviour? Why Chrono doesn't implement, for example, radial bearings imposing non-ideal (not-exactly-free) rotation?

Thank you in advance,

Patrick

[Radu Serban]

Patrick,

 

A couple of options:

 

1. If you only want to add viscous damping (and maybe also a linear rotational spring), you can activate the “ForceRz” on the revolute joint and set a spring coefficient and/or a damping coefficient. Something like:
       revolute->ForceRz().SetActive(true);
       revolute->ForceRz().SetSpringCoefficient(spring_coeff);
       revolute->ForceRz().SetDampingCoefficient(damping_coeff);
   See ChLinkLock.
   
   
2. Alternatively, you can add a rotational spring damper actuator (ChLinkRSDA) for which you can specify the torque function through a user-provided callback. That way, you can implement whatever function you want, including one proportional to the current load. See demo_MBS_rot_spring for an example of defining a ChLinkRSDA torque callback.

 

--Radu

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