2010 Drive Trains

2012 PneumaticsLightning Robotics FRC 862862An awesome way to do things

Do demonstrations of the cylinders here1Pneuma-what?Air! A pneumatic assembly is one that converts energy stored in compressed air to mechanical energy.Electrical EnergyCompressed airMechanical forceCompressorRelease of air862862Read slideElectrical energy powers a compressor, which compresses air. That compressed air is then released on command to do work.For example,Demonstrate by firing precompressed cylinder2Myth Pneumatics are HeavyFalse!Tiny investment, major returnsRequires only some heavy componentsPneumatics are usually very light in comparison to motors!No heavy motorsNo gearboxesNo sprockets, etc.862862In order to use pneumatics on a robot, you have to have a certain initial investment in weight. FIRST limits us to 120 lbs, so weight is a premium. There are some rather heavy components that you almost always have to have, such as a compressor and air tanks. These are heavy. The rest of the pneumatics are not.

If you use pneumatics in only one system, you may or may not end up adding weight to the robot. However, if they are used in multiple systems, then major weight savings can be achieved, because you only have to have one of the items such as the compressor.

The weight issue is much smaller than it used to be. Why? FIRST has introduced a number of lighter components, such as a smaller compressor. Furthermore, they have opened up the pneumatics rules to allow the use of components such as plastic air tanks.3New RulesFIRST made the rules much nicer this past year.Unlimited air storageMuch lighter compressor862862In the past, we were limited to only four of these tiny air tanks.Now, we can have as many as we want.

Compressor is significantly lighter.

4ActuationPutting into motionMotors rotate, cylinders extend and retractGood in different situations Motors Pneumatics862862Actuation means putting into motion

Pneumatics and motors both actuate mechanisms. However, they do so in very different ways. A motor spins, whereas a pneumatic cylinder extends and retracts.

It makes sense to use the mechanism on what its best for. If you have a device that travels over a certain distance, such as lets say an extending arm, chances are its better to use pneumatics. On the other hand, if your device needs to repeatedly spin, such as the wheels on drive trains, then a motor is your best bet.5What does that mean?Pneumatics good for fixed distances of travelMotors good for infinite travelExamples:Raising and lowering arm: fixedExtending and retracting arm: fixedDriving infiniteOperating a belt infiniteSpinning a wheel infiniteOpening and closing a claw - fixed8628626Infinite motion

862862The belts on 548s 2009 ball handling mechanism

7Fixed Motion

862862The extension and vertical travel on 548s 2011 robot8Recap of thatPneumatics are not heavy!If you need infinite motion, use motors. If you need a fixed distance of travel, use pneumatics.Dont try to use one for the other!862862Dont try to use one for the other it turns out badly. Believe me, I know!9Now, for the fun partHow to build them!

86286210CompressorsNew (Rookie) CompressorOld Compressor

862These are the two compressors. They suck air in and compress it until it reaches about 120 PSI.

New compressor is much lighter and smaller, but still compresses at about the same rate

Called rookie because only rookie teams get them in the kit; veteran teams have to buy their own

11Air TanksSimple Concept stores airUnlimited quantity

862862More tanks mean more air fits in the robot, but marginally increases weightNew tanks much lighter

Using more tanks doesnt mean compressor can compress faster!Does mean that more air can be placed on the robot at the start of the match, and that the compressor can have a bigger buffer

Gotta love that stock photo of a tank floating in space. How is it supposed to hold air?12RegulatorFIRST requires that:Max storage pressure: 120 psiMax working pressure: 60 psiRegulator does that!In line between tanks and cylinders862862The regulator closes a valve when the pressure on one side exceeds 60 psi.Safety feature. Ugh.

Appears as a black component with a knob on it all of ours have guages installed, which measures the low-pressure end. Also, it has an arrow. MAKE SURE THE ARROW IS IN THE CORRECT DIRECTION OF FLOW!13CylinderWhat actually does the moving!

862862Air enters through the rear of the cylinder and applies force to [this surface]. That pushes the piston outward. The air remains until it is time to return the cylinder, at which time that air is allowed to escape and air enters through the front of the cylinder, which pushes the piston inward.14Qualities of a CylinderBore Diameter:The diameter of the bore (inside) of the cylinder. Increasing this increases force applied by the cylinder, but also increases air used.Stroke Length:The distance the piston travels when extending or retracting. Increasing this increases air used.862862Why does the bore diameter increase force? It increases surface area, and PSI is Pounds per Square Inch15Solenoid ValveThe valve that controls air flowElectronically controlled2 typesSingle-solenoidDouble-solenoid

862862This is the valve that is connected to the individual cylinders and actually controls whether the air flows to the top or the bottom.

Double solenoids are what are used most often. They are what you see in the picture, and allow force to be applied both when retracting or when extendingSingle solenoids are much simpler. They fill the cylinder from only one direction, and to go in the other way let the air out. advantages: uses half the air.Disadvantage: requires an outside force of some sort to return the cylinder to its resting position; not reliable because the outside force could get stuck.16MiscellanyTubingBrass fittingsSafety pressure release valveTube connectorsPressure sensorTeflon tape862862Demonstrations!862862