Electrical Engineering & Electronics Design

Pneumatic is not a good choice if you want to precisely control travel since gases are compressible and will have some lag in controlling. And you definitely need a feedback.

As I see the system, it's two regulated (PWM, maybe) valves for each direction of movement. Difference in pressure on output of those valves produce movement of cylinder in either direction. And by PID regulating the difference, using feedback from the cylinder, you could precisely set the position.

Better and easier is to use stepper motor with a screw.

Hello Mohamed, can you tell us which kind of actuator you will use ?

it s exact what you said but the problem is i m making a fatigue testing machine i need a hight speed and force in the actuator and the stepper motor in not assuring those condition

do you have any other iddea ?

thnks

ofc i wanna use a pneumatic cylinder

https://www.youtube.com/watch?v=mw70qhuGKds

please check this video it s exactly what i want to do

It's hard to tell from the video, but here's how I think they did it:

1. Using propositional control valve, where solenoid current changes how far the valve is open, you can adjust speed of movement. You could connect to Arduino several ways: 1. A DAC output with a high current driver, Class A, so not very efficient 2. A PWM output, also with a driver, but potentially also a filter. This would electrically be kind of like a Class D Audio amp, the inductor will average the pulses into a changing current. You would want to use a very high PWM frequency.
2. A position feedback system. As was noted above, pneumatic systems compress so if the load changes the movement will be affected. You will need a closed loop software control to achieve the correct movement. If you are not very concerned about accuracy, and your load is very light, you might get away without this by just picking a cylinder that is highly overpowered for your load, then the difference will be negligible.

thanks for replying

and about the software i hate te developpe one i m not sure but i think the LABVIAW and Arduino are ther best for this case

do u have any other idea ?

please can i get more information about feedback