How can I properly drive an Ideal Translational Velocity Source in Simscape so my pneumatic cylinder rod actually moves?

I’m trying to drive a pneumatic cylinder as a limit-volume pump in Simscape by attaching it to an Ideal Translational Velocity Source; although the velocity command (± m/s profile) reaches the source, the cylinder rod never moves and the motion sensor reads zero—what could prevent motion despite a valid S-port input?

Answer 1

[Tridib]

Hi @Sadegh,

Since there are not many details about your current setup, here are some general things you can check that might help:

• Make sure both the cylinder and the Ideal Translational Velocity Source are connected to a Mechanical Translational Reference. If this connection is missing or set up incorrectly, the cylinder rod will not move.
• Check that the rod of the cylinder is not blocked or held still by other parts or connections in your model.
• Look at the pressure in the cylinder chambers. If both sides are at the same pressure or open to the atmosphere, there might not be any force to move the rod. Also, if the air cannot flow in or out, the rod will not move either. Make sure you have the right pneumatic sources and vents.
• The Ideal Translational Velocity Source tries to set a certain speed, but if the rest of the system cannot keep up, nothing will move.
• Sometimes, if the model is too stiff or not set up with enough constraints, the simulation will not run properly.
• You can also use the Simscape “Model Diagnostics” tool to check for any missing connections or setup problems.

Hope this helps!