I am using SW 2009 with CosmosMotion for inverse dynamics/kinematics. I am trying a very simple example: a moving object on a plane, constrained to follow a sinusoidal trajectory sketched on the plane. I use the "Assembly Motion" study by giving the initial and final position of the moving object over the path and it works fine. But my purpose is not animation but dynamic/inverse kinematic analysis, thus I need CosmosMotion to drive this object by inserting a force. I tried two different methods to make this mate: 1. Coincident mate: by making a point of the car coincident with the path (standard mate) 2. Path mate: by making a point of the car to follow the path given by the curve (advanced mate) None of these methods works with CosmosMotion. I apply a force on the object, which is mated with the sketched curve, and when I run the simulation the objecto complete igonres the constrained path, moving in straight line, as if it was not constrained. I am pretty sure the solver is ignoring this constraint. However, in page 80 of the "What's New in SoliWorks 2009" it is written it should work. Unfortunately I do not have the MazeGame.sldasm to check how it was done, because I think that could answer a lot. Does anyone here had the same problem?