How to move the rod of a cylinder?

I am starting with simhydraulics, and my target is to move mechanically a Double Acting Hydraulic Cylinder, to obtain an hydraulic flow between A/B ports.

I have joined a Source Sine Wave to an Ideal Translational Velocity Source (with SPS converter), and this one attached to the rod of the cylinder.

The problem, is that having only 0.4m of possible displacement, when I graph the position of the rod during the simulation, it moves from 0 to a bigger number than 0.4 (depending of the amplitude of the source sine). Briefing, the rod moves more than the maximun displacement.

I want to know if it can be configurated and/or if there is another better system to simulate the moving of the rod, instead of using the velocity as parameter.

Thanks, Alain

Answer 1

[Yifeng Tang]

So far, the only way in Simscape to prescribe a mechanical motion is using a velocity source, while in Simscape Multibody, the only way is to prescribe the displacement. I suppose the best way to make sure the resulting displacement from a velocity source make sense is to do an integration of the signal, with an initial condition consistent with the cylinder initial position, and scale the velocity signal up or down to get the displacement you want.

Otherwise, it's possible that the piston will move beyond the limit. The hardstop force is likely huge, but the velocity source doesn't care, because it's "ideal" and will generate whatever force needed to get the prescribed velocity.