What is the Best Control System for Compressed Air in a Drone?

[Andr5w5]

Hey,

I'm working on a project to build a drone which is powered through air jets. The drone needs a valve control system which can control the flow rate (hence the thrust) going to each nozzle in order to adjust it's altitude and stabilty.

I need to set up a circuit which can electronically control a valve to alter the flow rate of air (coming from a constant pressure supply - 85psig). The system is to be used to control the flow rate of air in order to control the thrust output from a nozzle.

I have been looking into proportional solenoid valves (i.e. http://www.smcpartbuilder.com/categories/cat/127096) where the valve position is altered by controlling the supplied current. My worry with these kind of valves is that they won't be accurate/repeatable enough or precise enough to provide the level of air flow control that I require. My plan had been to map the valve position to the output thrust to allow control of the thrust however in order to gain precise control of the flow would I require a system involving a mass flow rate controller? (something like this: http://proportionair.com/electronic-flow-controls/medium-flow-control/)

My experience with pneumatic systems is very limited and I wonder if anyone has any suggestions for a system which could do what I need?

 

[MHrtz]

So, essentially, you are need an electronic control system for compressed air. I'm assuming you were asking for a control sequence rather than for actual devices to control. I think you are on the right tack with the flow control device with the transducer. You will definitely need that. You will probably also need some sort of PLC to act as the brain for the system as well as a means for maintaining a constant air pressure. This means the system has the be capable of ramping up and down to control the pressure setpoint. Obviously, as valves open and close, the system will experience increases and decreases in pressure.

Say you wanted to begin an initial takeoff of the system. The process would be something like this:

1. User inputs a parameter (i.e. vertical direction@50%)
2. Signal goes to PLC. PLC tells the valve to open to 50%.
3. Valve begins to open, air flows through the valve, supply pressure begins to drop.
4. Mechanism providing the supply air speeds up to increase flow and maintain pressure.

Speed control on the supply pressure is very important because if the valve closes to quickly and the system can't adjust in time, the drone could explode from being over pressurized. Either that or the drone will launch like a rocket but not be capable of landing since there won't be air left to control the descent. As for the actual speed and precision of the controls, these are things that can be tuned or programmed to an extent but the valve will have its limits. You will probably want to play around with it and determine how much precision you actually need.

I hope this is what you were looking for.