Introduction to Pneumatics

Slides by Raul Olivera from FRC 111 –
› Presentation from the FIRST Championships in
FRC 358
› Lots of great resources!
FIRST Pneumatics Manual
› “The study of the mechanical properties of air and other
› The system on an FRC robot which uses pressurized air to
transfer force
Pressure = matter pushing against matter
› Object pushing against another object
Absolute (psia): true matter-based pressure
› 0 psia - no matter present to press against objects
› Not too important in our designs
Gauge (psig): Relative to Atmosphere
› 0 psig - pressure in equilibrium with atmosphere
› All regulators and gauges based on this
› At sea level: 0 psig = ~14.7 psia
Pressure = Force / Area
 Force = Pressure X Area
 Example: 30 psig in 2” diameter cylinder
30 psig
Area = pr2 = p(1”)2 = 3.14 in2
94.2 lbs
Force = 30 psi X 3.14 in2 = 94.2 lbs
Low to high force applications
› Up to 188 lbs (plus any mechanical advantage in
› Can vary force by changing pressure
Linear and rotational motion
Two positions
Flexible design options
› Linear is much more common
› Great for applications where a motor would stall
› Open/close or on/off applications
 Claws, lifters, pushers, pokers, levers
 Shifters and clutches
› Excess cylinder length can be accommodated in
 Move mounting point
 Push against rigid object
› Can start match with force applied, and keep it
applied at end of match
Relatively straightforward rules and
Mounting hardware included
Easy interface to robot
Can test manually without code
FIRST provides instructions!
Economy of scale – easy to add more later
Easy to transfer energy from robot “base” to
› Flexible tubes
› Don’t need chain, belt, or perfectly aligned shafts
› All components except for cylinder can be mounted
High Pressure
(120 psi)
Working Pressure
(60 psi)
Lower Working
Pressure (30 psi)
› Mount with rubber vibration
isolation mounts
› Must power with Spike relay with
20 amp breaker (not fuse)
› Gets hot!
Pressure Relief Valve (Norgren)
› Must be installed on output of
› Vents at 120 psi for safety (in case
your code to shut off compressor
doesn’t work right …)
› Must check that this is calibrated
Pressure switch (Nason)
› Normally closed (compressor runs)
› Opens at ~115 psi (code to turn
compressor off when switch is open)
› Wire to digital input and ground on
digital sidecar
Accumulator (Air Tank)
› Check rules regarding # allowed
› Make sure to mount on high pressure
side to take advantage of higher
pressure storage!
Primary Regulator (Norgren)
› Restricts working pressure to 60 psi
max on output side of regulator
› Can adjust to less than 60 psi if
› Make sure arrow points in direction of
air flow!
Secondary Regulator (Monnier)
› Yellow ring
› Allows additional lower pressure
circuit if desired
› Provide readout of pressure in line
› Place one on high pressure side and
one on working pressure side (can
attach directly to regulator)
Plug Valve (manual release valve)
› Install on high pressure side
› Must be able to release all pressure in
› Must be easily accessed and labeled
on your robot
Cylinders (aka “Pistons”)
› Donated by Bimba
› Order to team specifications from FIRST-
specific options
› Single or double acting
 Single = spring-based return when vented
 Double = air pressure drives both directions
› Magnetic position sensing option
Solenoid valves (Festo/SMC)
› Switches direction of air flow to drive
cylinder motion
› Connect to solenoid breakout on CRIO
› Need a double solenoid to drive double
acting cylinder
› Can activate manually with blue buttons
› Pressurized air has a lot of potential
› Follow rules EXACTLY and be careful
 Rotation
› Difficult to control orientation of the end
of a round shaft
 Leaks
› Can be hard to find – so prevent them
with good assembly technique!
 Cut tubing straight and clean
 Tighten fittings with proper tools
› Use methodical approach to narrow in
on one area
Pipe thread wrap
› Too much is not a good thing
› Leave last 2 threads clear
› Avoid getting into valves and hoses
Extra components
› Bring spec sheets for non-KOP items to
Cylinders are sensitive to side loads
“Pulling” force is slightly reduced due to area
of rod
Large cylinders use a lot of air – make sure your
compressor and storage can keep up with
expected use
Plug valve must be closed before you start the
MYTH: Using pneumatics is complicated
› Simple system with detailed instructions, and it’s the same
every time!
› Robust system with fewer parts to fail
MYTH: Pneumatics is heavy
› 2013 compressor is only 2.5 lbs
 Could be left off robot to save weight (check rules in 2014!)
› Cylinders have high force/weight ratio (compare to
CIM+gearbox+chain+speed controller…)
› Adding a second, third, etc. cylinder is trivial
› Plastic air tanks are available
› Solenoid and tubing weights are negligible
MYTH: Pneumatic cylinders are uncontrollable
› Flow control valves can slow down motion
› Can choose piston length based on geometry
› Magnetic reed switches can be used to sense
piston position
MYTH: Pneumatics is difficult to program
› Program compressor to run when pressure switch
is closed – connected directly to digital sidecar
› Double solenoid consists of two on/off switches –
when one is on, other is off!
Use all 24v or 12v solenoids – don’t mix!
Even if you aren’t using pneumatics on your
robot, take advantage of the Bimba donation
– play with them in the off-season or have on
hand for next year!
Solenoids need a minimum pressure (~30 psi) to
work. Test your code with pressure in the
Clevis pins can be replaced with bolts for more
mounting options

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