I am using a VSO LowPro Proportional control Valve (https://www.parker.com/Literature/Precision%20Fluidics/Miniature%20Proportional%20Valves/VSO%20LowPro.pdf) to regulate pressure into a closed actuator.

I am wanting to try and model this system in simulink but I am unsure on how to model this valve. I have done circuit modeling of electrical systems but not electrical mechanical systems and general you can get the transfer function from the response of the system. However could you use flow rate vs pressure to model the system? enter image description here

Any help of this would be greatly appreciated.


  • \$\begingroup\$ It depends on how simple or complex the model should be. The data sheet gives a 'response time' of 10 ms, which I take to be the steady-state response time, in which case a first order exponential with \$ \tau = \small 10/5 = 2 ms\$, along with a constant gain, might suffice. \$\endgroup\$
    – Chu
    May 5, 2019 at 8:55

1 Answer 1


You would use a linear regression curve for the mA vs flow rate for the selected with some 5 to 10 % hysteresis then multiple that curve gain above threshold by the input pressure curve with a linear constant if operation below 50% max pressure.

This is a 1st order approximation.

For better accuracy, modelling the exact part with Excel curve fitting the range above threshold can yield a family of curves that can be used to compute the expect flow vs measured flow rate and then adjust for error reduction. By always choosing to regulate on the rising current curve, you can avoid the hysteresis.

enter image description here

From testing, you may find that the threshold also shifts with input pressure, P so another coefficient on the threshold using P/25 {psid} to scale that threshold.

I do not know how to use Simulink, but the best tool is the one you know how to use. I could probably model it in excel or even Falstad with a pot control, pretty quick, using Zener curves with a defined series resistance and threshold voltage for current and a capacitor with an AC sweep for hysteresis at some frequency with DC bias.

Example : Falstad
enter image description here

  • \$\begingroup\$ Any questions?...... \$\endgroup\$ May 5, 2019 at 15:05

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