FIRST Pneumatics - Oregon FIRST Robotics

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Nov 13, 2013 (3 years and 8 months ago)

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FIRST Pneumatics

Team 1425

Wilsonville Robotics

Agenda


Components


Basic System Design


Applications


Tricks of the Trade


Resources

Components


Compressor


Accumulator


Tubing


Fittings


Release Valve


Popoff Valve


Regulator and Gauge


Pressure Switch with Spike Control


Solenoids


Actuators

Compressor

Back



Used to compress ambient air to do work for you.



Powered by 12 VDC. Eats your battery if you run it continuously.



DC power is connected through a Spike Relay, controlled by robot controller



On/Off control accomplished by monitoring a pressure switch



turns “on” at approximately 95 psi, turns “off” at approximately 115 psi



wired directly to a digital input on robot controller



will need to be programmed by Software Team



Do not put pressure switch in series with 12VDC supply to compressor

Compressor

12 volts DC

High pressure
air out

High pressure
air out

Accumulators

Back



Also known as “air tanks”.



Provides local storage for compressed air, to provide high instantaneous air

flow and reduced compressor operation.



Must be placed in circuit immediately after the compressor.



The more tanks you place, the less often your compressor needs to run for

each actuation of your pneumatic system. Each tank adds weight.



If your air needs are very low during a round, it is allowable to charge your

air tanks between rounds, and eliminate compressor from your robot.

Tubing

Back



Flexible and light means of getting air from compressor to other parts.



If you wish to substitute tubing other than what is supplied with kit, be sure

that you can prove substitute meets or exceeds working pressure.



Greatest challenge is routing tubing among moving parts so that binding and

pinching does not occur


zipties are your friend.

Fittings

Back



For connecting between devices.



Typically use brass for fitting between devices, or quick connect fittings for
connecting tubing to devices.



Lots of choices! Examples are:



Plugs for plugging extra holes



Right angles for making tubing routes compact and out
-
of
-
the way



Nipples for connecting between distribution blocks and devices



Use Teflon tape on all male threads, but leave first two threads bare.


Otherwise tape will get into your system and clog tiny holes you don’t

want clogged.

2 tubes

into 1

2 Tube Tee

into a device

Flow Control

Brass

Tee

Elbow

Release Valve

Back



A single valve on the high pressure side



Used to release all air pressure to make system safe to work on


Popoff Valve



An automatic valve on the high pressure side



Prevents high
-
pressure side from getting too high



Can be mounted directly to the compressor


Regulator and Gauges

Back



For setting the working pressure on the low
-
pressure side of your system,

and being able to see what you have set it for.



Regulator must be placed in line immediately after the air tanks.



Maximum downstream pressure is limited to 60 psi by FIRST rules.



Additional secondary regulators (with yellow ring) are supplied if you want to

have other circuits at even lower pressure.

Pressure Switch

Back



For providing a means for your robot controller to know when to turn the

compressor on and off.



Simple electrical switch which “closes” when the pressure is below 95 psi,

and “opens” when the pressure is at 115 psi or above.



Must be used, and must be mounted in the high pressure side!



A Spike Relay is used to actually control the DC power to the compressor,

not this pressure switch!

Solenoids

Back



Also known as “electric valves”


Provides a means for your robot controller to control air flow to a linear

actuator or rotary actuator.



Supplied in kit are



double solenoid (two electromagnets) energize one to make ram
extend, energize the other to make ram retract, ram will stay put when
both are de
-
energized.



single solenoid (one electromagnet) energize to make ram extend, ram
will retract when power is removed (ram won’t stay put)



Spike Relay is used for each electromagnet



Each solenoid has an override button, to actuate without power

Power here
and air goes
this way

Power here
and air goes
this way

Actuators

Back



Come in two types:



Linear (known as Rams) (motion: extends and retracts linearly)



Rotary (motion: rotates a shaft clockwise/counterclockwise a fixed
amount)



Provides a variety of uses for lifting, pushing, shifting gears, actuating

“paddle” mechanisms



The power available is a function of physical size of the ram and the air
pressure.



A 2” diameter bore at 60 psi can create 188 pounds of force



You get different force upon retraction and extension



Not a good choice when precise control over movement or position is

needed.

System Design

Compressor

Release valve

Pressure Switch

Gauge

Accumulators

Regulator

115 psi max

60 psi max

Flow Control

Solenoid

Battery

Spike

Robot

Controller

Spike

Applications


Controlling a flapper mechanism


Actuating a gear shift mechism


Opening/closing a grabber


Lifting a portion of a robot


Deploying a large device, like a ramp

Tricks of the Trade


Cut the tubing with a sharp knife, squarely


Don’t use side
-
cutters, you’ll get leaks


The third time you insert tubing in the fitting, it’ll
leak (leave tubing long)


Build a manifold to keep a few things together


Pressure switch


High pressure gauge


Release valve


Regulator and distribution

Resources


2007 Pneumatics Manual from FIRST


http://www2.usfirst.org/2007comp/other/200
7%20FRC%20Pneumatics%20Manual.pdf


There are many resources listed in this
manual, including manufacturer’s
specifications

Parting Words


Remember these three rules


If it is pneumatic, it will leak


It’s easier than it looks


Anything worth doing requires one more trip
to the hardware store


Best of luck from Team 1425