radman:
Why not just have vertical air jets in the corners to raise the robot off the ground, then horizontal thrusters to move around.
I think the OP is saying the robot supports itself on legs powered by compressed air - it's not a flying vehicle. Compressed air is a very inefficient power supply for this type of thing because air is so compressible - the only way to drop the pressure is by throwing the energy away.
I don't understand the purpose of having a gyro on each leg. Wouldn't it be better to have a position sensor tell you the angle of each joint and use that as input to your position feedback system? If you're hoping to keep the body horizontal (rather than parallel to the ground) that's going to be quite hard to do and will involve the sort of gyro/accelerometer system used on flying vehicles. In that case it'd probably be best to seek help in forums relating to autonomous drones rather than try to develop it from scratch yourself.