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The effect of motors in a "kinematic"study?

Question asked by Mitch Gilbert on Aug 3, 2010
Latest reply on Aug 12, 2010 by Mitch Gilbert

I'm trying to perform a "kinematic" study involving a mechanism with cams. At this point I don't care about the forces only the timing & motions.  I have a portion of the mechanism modeled (not the cams), I created the cam motions using linear motors (& CSV files) applied to the parts controlled by the cams.  The motors were attached to the moving parts (with a linear degree of freedom) & a dummy part (completely constrained).  One of the cams has a spring in the follower system that "truncates" the cam motion when the follower hits a stop (on each end of the stroke). I modelled the spring as very stiff because I don't care about the forces and didn't want any dynamic effects (compression due to acceleration).  I thought the motors simulated infinitley powerful motors i.e. the motors would always achieve the desired position regardless of the required horsepower.  However, this doesn't seem to be the case.  The motor that drives the part through the spring seems to behave like an undamped spring-mass system & basically goes nuts (regardless of the spring constant).  ProE mechanism distinguishes between a kinematic motor & a dynamic motor (i.e. needs a torque curve). How do the Solidworks Motion motors work in this regard?

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