Simscape: Base excitation of a dynamic Seat-Model: No oscillation behaviour.

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.

Thanks! Obelix

[Swarooph]

I don't see the pictures attached. And a model would work better to understand what you are trying to do rather than pictures.

Answer 1

[Steve Miller]

Hi - as mentioned, we do not see any pictures. I suspect your scissor mechanism is not properly configured, and that your upper plate and lower plate cannot move with respect to one another.

If you can share the model, we could tell you more.

--Steve

Answer 2

[Pavel Osipov]

Hi! Steve is absolutely right.

I believe that almost everything in Obelix is ready, but you need to carefully monitor the local coordinate systems. I've had the same effect many times. Simscape modeling takes some getting used to. In Mechanic Explorer, you can see all bodies and their associated coordinate systems. Long am fluctuations and will try help, if you not decided to its task himself. Good luck!