Hallo, I have build a Simscape Multibody model of a dynamic Tractor-Seat. I modelled a base excitation using a Prismatic Joint between World Frame and Bottom-Plate. The upper plate is connected to the bottomplate using a scissor-kinematic and an controlled pneumatic piston. I expect that the upper plate begins to swing when the bottom-plate starts to move. The position is messured with a transform sensor between the upper plate and the world frame. The problem is that the upper plate just moves up and down like the bottom plate. There is no oscillation of the upper plate. I have tried different spring stiffnesses and dampers. I can measure the Forces at the wheels under the upper plate but it does not move, except the movement of the excitation. Does anybody know what I am doing wrong? There are some pictures so that you can get an idea what I am talking about.