Pneumatics

Utilizing Pneumatics

Pneumatics are not scary, despite common belief They are the easiest way to add motion; huge difference maker between teams who constantly perform well and teams who have highlights and lowlights. Using a motor is way more complicated compared to what pneumatics can do for simple situations. Basic, simple, using compressed air to do work; covering air pressure to mechanical energy

Three components:

Storage

Solenoids - controls

Actuators - do work

Full system

High pressure, Low pressure, Lowest pressure [Insert system overview slide, David] Everything to run pneumatics system is here except for wires to control it good idea to create similar system before build season; good practice and good prototype for testing, getting the hang of pneumatics

Starting with the air

All air used comes from a compressor A compressor can be either on board or off the robot Any compressor can be used as long as it meets these specs:

  -Nominal 12V

  -1.05 cam (cfm metric for how much air can be pushed through at a certain time)

These specs must be followed, whether the compressor is on-board or off

Potential options for a compressor

2010 KOP and Earlier

-Thomas Compressor

2011-13 KOP

-Viair Compressor

-VIAIR 00090

High pressure and storage

Air is stored at 120psi Air can be stored in any pressure Vessel rated for 125psi Working Pressure Must have a pressure transducer, blow off valve, and a dump valve

More on Storage

Greater storage generally means less time the compressor runs Consider how many cylinders and size More storage on the robot, more air you can keep and the less you have to run to compressor Don’t be afraid of running compressor, but it’s good to not be using it all the time

Dump valve, pressure reg., and blow-off valve

Commonly assembled inline with brass All have to be on high pressure side before 60psi regulator Make sure it isn’t just at 100, because you would constantly dumping air Have it be easily accessible One of the refs has to be able to see it and interact with it easily, if they can’t, considered illegal

Low pressure side

Starts at 60psi regulator can be 60psi or lower Too low a pressure can cause solenoids to not trigger

Solenoids

Essentially an on/off switch for air Inputs and outputs based on signals [Insert 3 photos of solenoids from slideshow David] Work great with prototyping/testing, programming not required; easily activated with a button push.

Things to consider when choosing a solenoid

Voltage: 24V vs 12V? Single vs double? Use a manifold? Does it stay within FIRST rules? <— important Make sure to plan ahead

Cylinders

Bimba gives teams 3 free cylinders Things to consider when selecting a cylinder

Force required

Distance device needs to be moved

Space available

Bent cylinders are essentially useless One directional; follow the air flow Slightest bend or scratch can affect how air goes into the cylinder

How to calculate the force of a cylinder

Take your working pressure, WP, in psi Bore of cylinder, B in in^2 For extension force = WP*B

Cylinder Length

Stroke: Distance from cylinders shaft will extend from its starting point

Control System

Much simpler All components to one module Module controlled by RoboRIO CAN controlled “plug and play”

How to effectively use Pneumatics

Ensure a Pneumatic cylinder is best suited for the application Remember cylinders are “digital” They have an extended and closed position, nothing in between Consider where else you will be using pneumatics Carefully plan the layout Know where: You will mount the compressor your storage tanks will reside Your solenoids will go Try to use a manifold if possible Plumbing a pneumatics system is like wiring Do it slowly and carefully, more time spent setting up = less time troubleshooting Mistake everyone does Make sure you’re making a clean cut every time Cut it longer than needed first, then trim it down Air leaks cause a pneumatics system to quickly fall apart

Examples of bad setups

“spaghetti” Make sure everything is neat and laid out, similar to clean wiring, labels may be applicable

‘Okay’ setup

Tubing is great, everything is contained Wiring is unkempt Closed box means difficult troubleshooting

‘good’ setup

Clean, everything has it’s own place Organized

At the competition

Inspection Let the inspector do their job Point out components when asked Don’t try to hide anything Help it be quick; everyone wants it to go by fast Keep and eye out for any leaks charge tanks before match Be vigilant; going out for lunch, charge tanks before hand See a worrisome leak, ADDRESS IT Dab soapy water onto connections. If you see more bubbles, that means leakage

Hints and tips

Little things that make life easy Always cut tubing so it has square ends use and properly apply teflon tape Different color tubing Manifold less brass Make sure to buy high quality tubing, cracked tubing is not good make sure bought tubing is legal Building robots, not building a house, weight matters

Should you use pneumatics?

Pneumatics is simple, but there are other ways they add a lot of weight demand on battery speed force/springiness space required

Useful resources:

www.bimba.com

www.autmationdirect.com

freelin-wade.com

smcusa.com
			and more on the slide show [David this is your cue]