Overview of PneumaticsOverview of Pneumatics

1425 Wilsonville Robotics

Tim Bennington-Davistbenningtondavis@ixiacom.com

(503) 449-9507

Why Use Pneumatics ?Why Use Pneumatics ? To power Actuators Powerful, reliable, durable Good lifters, long extension, quick action

for short throws

Typical ApplicationsTypical Applications Two-position linear applications◦ A “lifter” or “gate”◦ Transmission shifter◦ Arm extender

Means to impart energy ◦ Load the spring of a kicking device

Limited-arc rotary applications◦ Gripper ◦ Arm Elbow or Shoulder

What will it cost you?What will it cost you? Weight Battery power Space on the robot Logistics to get the right parts

Pneumatic SchematicPneumatic Schematic

Pneumatic SystemPneumatic System

Elements of the SystemElements of the System Compressor Safety Release Valve Air Tanks Pressure Gauges Pressure Regulator Pressure Switch, vent valve Tubing and fittings Solenoids Actuators

Pneumatic SystemPneumatic SystemCompressor

Safety release valve

Air Tanks

Pressure Gauge(high press)

Pressure Gauge(working press)

Regulator

Pressure switch and vent

Solenoid

Actuator

CompressorCompressor New model in 2011 – lighter Earlier model also legal (probably) Mount with rubber mounts to solid

surface Power with Spike (replace fuse with 20A

circuit interrupter)

Safety release valveSafety release valve Releases at 120 psi – prevents over-

pressure condition Must be placed on high-pressure side

(prior to regulator) Recommend mounting at compressor

Air TanksAir Tanks Reservoirs for pressurized air May use more than one Typically used on high-pressure side

Gauges and RegulatorsGauges and Regulators Norgren regulator mandatory, regulates

high pressure side down to 60 psi Relieving regulator to deal with pressure

spikes from mechanical compression Must have gauge on high pressure side,

and on low-pressure side

Pressure switch and valvePressure switch and valve Switch opens at 115 psi, closes at 95 Must be connected to digital input on

digital sidecar – NOT in series with power

Valve is to release pressure from system

TubingTubing Must have clear pressure marking Typically 0.25” OD Always cut with tubing cutter, square end

SolenoidsSolenoids Driven by pneumatic bumper on cRIO Available in single- and double-action 12v or 24v, compatible with pneumatic

bumper

ActuatorsActuators Typical device is a linear ram Available in many sizes◦ Length (throw)◦ Diameter (bore)◦ Mounting configurations

3 cylinders are available at no cost but you must order them

Useful Tricks – Flow controlUseful Tricks – Flow control Flow control valves◦ Mount at air inlet on actuators◦ Control speed of action, not force

Useful Tricks – Magnet SwitchUseful Tricks – Magnet Switch Magnetic switch option◦ Mount switch to side of ram◦ Use digital input to cRIO to detect switch

closure◦ Lets software know when piston is at certain

position◦ Turn “2 position” ram into “multiple”◦ Requires double-action solenoid

More on SolenoidsMore on Solenoids Single Action◦ One electrical connection◦ Controls “two position” operation

Double Action◦ Two electrical connections◦ Enables multi-position operation

Helpful HintsHelpful Hints

System tradeoffsSystem tradeoffs Big rams use more air (stroke and bore) Frequent use of air during match can outrun

your compressor If your air use is limited enough, you can

consider charging tanks in the pit, and not mounting compressor◦ Save weight, cost and battery power

Good FactoidsGood Factoids Order your actuators EARLY. There are lead times

involved. Cut tubing square, and don’t tolerate leaks. ◦ Eats your battery life◦ If you count on a “pre-charge” lasting, and there is a delay in

field play, your air leaks out.

Get on the Bimba website and get familiar with their parts

If you want magnetic switches, you must order magnetic rams.

Get your three actuators, even if you don’t use them this year

SummarySummary Well-suited for: ◦ Fast movement◦ Two-position mechanisms◦ Creating substantial force◦ Sustained Holding

Not so good for◦ Precision position control◦ Sustained movement

Exercise safety

Great resourcesGreat resources FIRST website◦ Pneumatics Manual◦ Rules from 2011

Google “FIRST pneumatics”◦ You’ll get several hits from teams who have

done tutorials, including calculations