[pmangels17]

I was going to say a similar thing. One caveat to pneumatics is that they require an entire air system: storage tanks, tubing, gaues, solenoid valves, and a compressor all need to be added to the robot in order for you to use pneumatic actuators. A compressor isn't necessary to have on the robot, but you'll need some way to supply compressed air if you exclude one. You also have to think about a safety system like a pressure relief valve and quick release to vent all the air in the system.

That being said, if you have a thing that only needs to be in two (or three or four if you use multi-stage cylinders or multiple cylinders) positions, pneumatics are a simple and reliable way to achieve this. Motors and gearboxes add a different set of complications, namely making sure the motors and gears you select give you the correct amount of torque to get you where you want when you want to get there. You'll also need some sort of feedback sensors (limit switches, potentiometers/encoders, etc) and some sort of feedback control loop (not necessarily PID control, but probably more complex than the software for pneumatics). Both solutions have their advantages and disadvantages, and there are other solutions available as well, but this is what makes engineering challenging.