[Jeff Waegelin]

When discussing the "weight issue" of pneumatics, I like to use an analogy to economics: pneumatics have high fixed costs, with low marginal cost, while motors have high marginal cost but low fixed cost. In this case, "cost" can represent weight and complexity of design. When you add pneumatics to a robot, there are a lot of support pieces you need (compressor, tanks, etc.) that weigh quite a bit. However, each individual cylinder represents only a small increase in both weight and complexity of your pneumatic system. Thus, the "cost" of adding pneumatics to a robot is high, but once you've added one, the "cost" of a second is pretty low.

Motors, on the other hand, don't really require any additional fixed weight, as everything they need (battery, RC, breaker panel, etc.) is a required component of any robot. Adding each one, though, can add lots of weight for the motor and any associated gear reduction. So, unlike pneumatics, there is no real fixed startup "cost", but each additional motor can be a major increase in "cost".

My philosophy in using pneumatics in FIRST is based partly on this idea. If I use pneumatics, I generally prefer to use them for as many functions as possible. Once I've added a compressor and all the other support pieces, it's easy to add more, and can be a very weight-efficient plan. On the other hand, if I only have one use for pneumatics on a robot, I will generally try and eliminate that mechanism, or change it to a lead screw or other motor-driven mechanism, so as not to have to add all the weight associated with that initial pneumatic cylinder.

All things considered, I like pneumatics. They're fairly easy to work with, fast, reliable, and consistent. Lightweight manipulation on the end of an arm is also a great feature. But, if I had no pneumatics on my robot, and a choice between adding 5 lbs. for a small motor and lead screw, or 15 for all the pneumatic equipment... it's an easy choice.