Pros and Cons of Using Pneumatics

[EricRobodox]

EricH nailed it on the head i think. only missing one more major pro though. Accuracy. You know exactly where the piston will stop and how far it will move. With motors, its a lot harder unless puting limits on it which is more time consuming. RoboDox have been using pneumatics every year almost since our start, and have been one of the first teams in FIRST to use them. This year we didnt use a compressor, which is legal. We charge it before each match. This saved a lot of weight and allowed us to be a unique robot as our actuators were not for shifting, but lifthing the balls. ahahaha. balls. ahahah. But i think pneumatics are very good, and people over look how much potential they have.

[nparikh]

Pneumatics are neat....but I think they're a real pain. Don't get me wrong, we used them in our 2003 robot, and that went to the Finals on Einstein..so it was by no means an unsuccessful design..but for the most part, I think it's caused more grief than it's worth. Leaks, breakages, etc..are a pain, GR.

As FIRSTers say, Keep it short and simple . Pneumatics tend to get on the more complicated side..if there's an easier / more efficient / (any other way) to do something, I'd go that way.

[slickguy2007]

We used pneumatics in 2004 and 2005 and we didn't have any problems. We just made sure that we had an onboard compressor, and we made sure that the air tanks would fill up on the field before we needed them again. The pneumatics operated only things that we knew wouldn't interfere with normal game play. We didn't have too many problems with air leaking out of the tubing, but if we did we just used the good ol' soap&water test on the tubes to find the leak.

[EricRobodox]

I never had a problem with pneumatics. My friend did the most of it, but i was right there with him putting it together. I give him all the credit, he deserves it. But the point is, it seems easier than limiting a motor, because with a motor you need to program the limit process as well as speed and many more variables. With pneumatics, you use flow controls for speed which allows you to change the speeds a lot easier, its just an On/Off if its a single solenoid to activate, and its just a switch. When hosing everything, just make sure you cut perpendicular to the hose and also all your connections get 3 windings in the correct direction with teflon tape. I never really had problems with pneumatics. For leaks, i just listen for the leak, usually the best tool to use. soap and water takes a while, although i have helped other teams with their pneumatics with this method. With pneumatics, its easier to do something once and slow, than fast and redo it. plus, it makes you look better.

[Astronouth7303]

The big problem (and the reason our team hasn't used them since 2004) is the 10lbs weight you add for your first cylinder. We've never had a great need for pnuematics, our designs have always made use of 1 or 2, if any.

The binary nature of them (esp the larger cylinders) is no longer a problem for us. We dealt with it in 2004; that arm stopped in the middle. (Albeit, the drift and equalization times could use tweaking. But it stopped half-way up.)

[Daniel_LaFleur]

Anything you can do with Pneumatics you can do with motors (and vice versa). Thus it comes down to the application. Most people who use only motors tend to look at each actuator as a separate system rather than as a small part of the whole.

Case in point: If I have a robot that has 7 actuators for a claw / gripper / arm I could use 7 separate motors (each with their own encoders and limit switches ) or I could use 7 cylinders (with hard stops), a compressor and a storage volume (1 system). Each has their place.

Another advantage of using pneumatics is that you can set whether the energy is released or maintained at power-down.

Examples:
1>Say you want a claw / hopper to drop / dump what its carrying at the end of the match ... just set the valve to open the cylinder to atmosphere.
2> say you to ensure the robot does not move (even if on an incline) when power is turned off ... set the valve so that when power is turned off, pressure goes to a cylinder that lifts the robots wheels off the floor.
3> (from a couple of years ago) Launching a tether back to your side of the field to score points in a zone.


Energy wise both use approximately the same amount of energy, but the pneumatic system uses it over a longer period of time (utilizing stored energy much better), thus lowering the chances of 'popping' a circuit breaker.

[KenWittlief]

Originally Posted by Daniel_LaFleur

Anything you can do with Pneumatics you can do with motors (and vice versa).

I dont think this is entirely accurate if you take all design parameters into consideration

you might be able to get the same kind of motion from a motor/lead screw / servo... as you would from a pneumatic cylinder

but I dont think you can match the speed and power available from a pneumatic cylinder in a package of the same size, weight, cost, availability, simplicity...

Sure you could run cables all over your robot, or push rods, or torque rods to get mechanical power to the end of a long arm, but that would be very complex compaired to putting a cylinder out there with two plastic tubes.

There are tradeoffs going with pneumatics or motor actuators. For some applications pneumatics are definately better.

(BTW, to keep everything on an equal footing, dont forget that for each motor you also need a spike or Victor, a fuse, heavy copper wire, crimp terminals, a feedback circuit or limit switches + SW development time and effort.)