programmable air pillows

[scottmurchison]

I am designing a project that needs small pillows of air that I can quickly partially inflate and deflate. I'm talking about a pillow no bigger than 2" diameter for example. I want to use three of them to support a load less than 5 lb. I imaging using a air pump with tank and regulator and the pillows themselves would each utilize two 12V solenoid valves, one to allow air into the pillow and the other to allow air out of the pillow. I would use a microcontroller like an Arduino to manage the solenoids to change the air pressure in each pillow. What I'm looking for now is parts and someone who have done something like this before. Has anyone out there ever experimented with air control like this?

[adafruit_support_bill]

Yes. I've built an Arduino-controlled device to sequence the inflation/deflation of a multi-chambered bladder. I experimented with pumps & valves from inexpensive portable blood-pressure cuffs. These were a little too slow for my purposes, so I went with a BLDC medical-grade pump from Hargraves. Plumbing was via 3/8" silicone tubing and servo-actuated pinch valves. Pressure was regulated via 4 pressure sensors attached to the bladders.

[scottmurchison]

Sounds interesting, but expensive.

[adafruit_support_bill]

All together it was about $500 in parts to build the device. Half of the cost was for the pump. Still quite economical considering that commercial versions of that device sell for the price of a luxury car.

If inflation speed is not an issue, you can probably get by with parts from blood pressure cuffs. I found some surplus cuffs on eBay for less than $10 each. Each one came with a small diaphragm pump, a solenoid valve and a pressure sensor.

[scottmurchison]

I think that if I can partially inflate/deflate a maximum of 10 times per second, I would be fine. I only need the bladder to expand/contract a few mm.

[adafruit_support_bill]

10 times per second

Hmmm. You won't be able to cycle a pump that fast. You will probably need to have the pump running full-time and a small pressure tank between that and the pillows.
The other issue is valves. To move air quickly, you need a valve with a large orifice & a correspondingly large solenoid. Large solenoids don't like to move that quickly either.

Instead of pumping air in one side and venting it out the other, why not build a closed system. You could have 2 sets of bladders and an actuator that squeezes one side to pressurize the other.