Hello! I am currently working on some penumatics and i need to persicly control it from a servo valve except i cant find any?(That aren't in the $100 + range) Any Reason? And Work arounds?
Look on AliExpress?
Give an example of what you are trying to do.
Be aware that the position of a pneumatic ram depends on the load as well as the air pressure. That is why they are usually designed to be driven to an end point with speed being adjusted by valves.
They are not designed to be positioned as you would a hydraulic valve. Oil does not compress while the air does.
Weedpharma
Im trying to make a robotic limb capible of lifting semi large loads and i need the emg sensors to power a servo valve to percicly control the flow and are there any compact things that work like this?
As air compresses, you will unlikely be able to precisely control the position of the arm. The control valve would need to be able to be modulated to allow small amounts of air to be applied. The lowering of the arm would need similar control.
While suitable valves are available, they are not cheap hobby prices.
Weedpharma
The stuff we use at work that could do this would mount on a rotary actuator then the control head mounts on top. The control head reads the position and compares it to the requested point and adjusts to suit. This would be a large bulky way of doing it. the price is also in the thousands.
Now depending on what you plan to lift and how accurate you want it the basic concept of feedback is still the same. The expensive stuff uses cams, springs and needle valves. this way the further you are from the set point the more air is allowed to flow.
Im sure that you can get feedback to the arduino then using a adjustable valve and some air solinoids you could make something that works im just not sure that it can be done for under a $100
If you are willing to go to electric motors then I would suggest looking at a power wheel chair motor gearbox assembly ( about $30 ). The motor has a brake and the gearbox amplifies torque. It would require 24v dc power. You would still require a sensor for feedback