MATLAB Answers


Simscape Multibody mutually dependant definitions

Asked by Sean
on 26 Jun 2017
Latest activity Answered by Steve Miller on 3 Apr 2019
I'd like to model two masses that are attached by springs and dampers (picture below). I'm interested in their behavior after they are let go and acted upon by gravity.
So far I have the following system:
I get an error stating that: "Coordinate systems CS1@Body1, CS2@Body Spring & Damper2/Body1 on the highlighted Bodies have mutually dependent definitions. Remove mutual dependencies among coordinate systems so that at least one coordinate system is directly or indirectly referenced to World."
Everything online says that this error is the result of a circular definition of the coordinate system. I don't think that this is the case in my model.
Does anyone know of a Simscape Multibody example that uses the Body Spring & Damper block?
Thank you very much for your help.

  1 Comment

Have you looked at this FileExchange entry? Seems like it is modeling the same system. It also allows you to specify some trajectory as well and see the response. If you wanted to see what the effect is just under gravity, comment the 'Extremity Trajectory' subsystem in the model. (Although I haven't looked at this model in detail, I am guessing that's what that does).

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1 Answer

Answer by Steve Miller on 3 Apr 2019

Hi - if you posted your model, we could debug it.
I would highly recommend you explore modeling this in Simscape Multibody Second Generation technology. You would use fewer blocks (the spring-dampers are contained in the joints) and would not have to create so many coordinate systems.


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