Help! Transfer Function for Hydraulic Electro-hydraulic actuator

[Hydromech99]

I am looking for help with a project that I am involved with for my post-graduate studies.

I will be performing the control design and some simulation for an electrohydraulic actuator for aircraft flight control surface actuation.
This is a hydraulically powered actuator that is controlled by a electrohydraulic servo valve, that uses current to two coils to control the position of the metering (flapper) valve. The feedback of the actuator position is by LVDT.

What I need is a rough model or transfer function to work with to start the simulation and control design.
Help! Any tips or information would be greatly appreciated.

Thanks,
Sean
M. Eng almost

 

[ScottyUK]

Search the web for Moog Hydraulics in England. They are usually quite helpful, although it might take a while to speak to someone 'in the know'.



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If we learn from our mistakes,
I'm getting a great education!

 

[sreid]

ScottyUK is correct. A quick seach on "servo valve transfer function" gave

http://www.servovalve.com/technical/new_tb_103.pdf

 

[Hydromech99]

Hi there, sreid and ScottyUK.

Thanks for the tip - that definitely will set me in the corect direction. Given the amount of variables involved in such a device, I will likely have to use a simplified model, for the purposes of synthesis and control design. That Moog document will be a huge help. Any more thoughts are appreciated. I am very impressed with this site, and have sent the link to all my colleagues and engineering friends (I work in flight controls and hydraulics, currently in a customer support role).

Cheers,
Sean