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Free standing entity in SimMechanics?

Free standing entity in SimMechanics?

Free standing entity in SimMechanics?

Is it possible to model a free standing entity in SimMechanics (ie. a robot with 4 wheels)?  If so, what joints would you use to "ground" the model or how would you otherwise simulate the robot's interaction with the ground?  It needs to roll around, so the friction between the wheels and ground needs to be taken into account.
What if it is a legged robot?  How could I model it walking around in SimMechanics?
Also, what if you wanted it to interact with a complex obstacle (ie. a set of stairs)?  Is this even possible to do in SimMechanics?  I'm seeing that generally to define the geometry of bodies you only identify the points of interaction with other bodies and their mass and moment of inertia.  Is there some other way to do this?  Can you perhaps use StateFlow or SimEvents to switch the supports around to where the interactions will be?
If not, is there some other simulink add-in that will do this?  I've looked around the website extensively and haven't found anything.
Finally, if all else fails is there some other modelling software I should look at?  I've been looking at another program called ADAMS, is anyone familiar with this?
I know this is a lot, but if someone could just answer at least a handful of my questions that would be very useful.

-Sam Boyce
Asst. Mechanical Engineer

RE: Free standing entity in SimMechanics?


I dont think simMechanics is appropriate for modeling the mobility of a 4 wheel vehicular platform. It is more suited to the modeling of linkage type mechanisms where at least one support can be a ground fixed revolute joint.

I would think a simulation for the mobility could be achieved by modeling the dynamic equations of motion for the chassis. This way the input to the system of equations could be the displacement of the tires from some starting elevation.

This paper may help.
If you are still looking for an add-on I would suggest seriously looking at simpack .

I know you've heard some of this before... But I hope whatever is new is helpful.


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