Connecting DC motor to a revolute joint

Hi

I'm trying to interface the DC motor block (Simscape Electrical) to a revolute joint (Simscape Multibody). The aim is to develop a simulation model for a Pendubot.

Following several examples I think (I hope) I've made the connection properly, including the Rev-Rot interface to feedback the joint velocity into the DC motor but I have a doubt. If I want to change the friction, where is the right place to do it?. I've noticed that I can change the damping coefficient in the revolute joint (which is what I usually do) but it can be changed in the mechanical parameters of the DC block. (Rotor inertia).

Find attached a zip file with the simulink model and the stp files. Don't mind the commented blocks, just trying to model the motor non-linearity.

Thanks for your help.

Best regards

Answer 1

[Juan Sagarduy]

Hi Vicente

It shall work in both cases, but it is more natural to do it on the Simscape side (DC actuator). This makes sense if u wanted to add friction later on.

Good luck Juan

[Vicente Casanova]

Thank you, Juan for you answer.

That's what I thought but there must be any difference. The parameter in the DC motor (rotor inertia) is mesured in Kg*m2 (momentum of inertia) and the one in the joint (damping coefficient) is measured in N*m/(deg/s) (viscous friction). I guess there must be some kind of equivalence. I mean, if the damping coefficient is e.g. 0.0001, which is the value of the rotor inertia to get the same results?.

Best regards

[Thi Pham Duy]

hello friend, if I want to add a coefficient of friction for the DC motor, how can I add it. I hope you can reply

Answer 2

[Vicente Casanova]

I usually adde the friction in the damping coefficient of a revolute joint (Simscape Multibody) connected to the motor. But I'm not really sure if it is the right form to do it.