Hi All,
Am an experienced Simulink user looking to do some simulation of mechanisms. I was looking at importing Solidworks drawings into SimMechanics to do the analysis but then found COSMOSMotion which looks like a better tool.
Anyone have experience of simulating mechanical systems with either package?
Thanks,
Mark.
CosmosMotion is integrated in SolidWorks, so it is a "purely mechanics" simulation system, where you can easily define joints, restraints, forces in 3D, and you can take advantage of Animator and CosmosWorks features to make animations and FEA studies of critical parts. However, when you need to simulate a system with feedback, control, complex trajectory generation, you'll need to dive into its (very) old fashioned ADAMS programming language. See the online help about "adams" to get the picture.
SimMechanics is an extension of a great "system oriented" simulation package : Simulink. In Simulink your system is modelled as connected blocks which define "transfer functions" between inputs and output. Each of your parts and each of your joints will be converted in a block by the cad-2-simmechanics tool, then you'll complete the diagram by adding source signals, feedback loops and automation devices in a much more comfortable manner than coding in adams.
A very interesting alternative to Simulink is Dymola by
Block diagram oriented simulation is in trouble with contact problems, for example when a part is in a conveyor and falls on another device. You'd need to define all the possible contacts as blocks, while 3D tools such as CosmosMotion use general collision (interference) detection. However, Block diagrams allow to model contacts and friction with much higher detail than the "impact" model used in 3D (CosmosMotion). The combination of the general collision detection with impact forces and frictionresults in long simulation time and, quite often, wrong results.
A difficulty with all tools including CosmosMotion is the conversion of assembly "mates" into cinematic joints (revolute, prismatic...), while handling "flexible" assemblies and other cad-related stuff. It works on simple models where mates have been carefuly defined using gormetry on connected parts. If your model has "design mates" such as the distance between reference planes of two distant parts, or if you didn't select the same parts to define the concentricity and the coincidence of a revolute joint, or didn't block the free motion of your screws, prepare to spend some time clearing the jungle of the cinematic joints...
Hope this helps.
( Looks like this answer is long enough to become a post on a blog soon ;-)
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