[Alan Anderson]

If you're worried about writing commands to control individual cylinders, you're probably not at the appropriately high level of abstraction. I suggest that you should be controlling subsystems, not actuators. The subsystem implementation should take care of the details of motor and relay and solenoid control based on commands for speed and state.

Don't extend or retract a cylinder. Instead, engage or disengage a brake, or lock or unlock a latch, or open or close a gripper. It would be appropriate to extend or retract an arm, if that's the motion you've designed it to do.