ARTICULATION
What is articulation?
• It’s the way a robot interacts with the field and game objects
• Articulation systems usually have manipulators (mechanisms that interface game objects directly)
• Many different types
Example
• Dumper in Clean Sweep– Articulation system
consists of dumper and intake (manipulation)
– Wheels roll balls into dumper
– Dumper lifts to unload on other side
– System accomplishes its task
Designing for Articulation Depends on
object Light? Heavy? Strong? Weak? Shape: Round?
Square? Where? Ground?
Raised? Autoloaders?
(put pics of diff objects)
Motors Different types for
different useso 3-wire motor
(standard)o 2-wire motor: more
torque, same speed/ more speed, same torque
o servo: 180º, good for claws, limited motion
Pneumatics Use air pressure Good for two position articulation systems that
require lot of torque (claw)/ transmissions No risk of motor stripping Needs compressor or else limited in number of
throws
Collection Systems
Intake Rollers
Quickly grab objects off ground
Relatively simple design
BUT... may jam (low torque)
Conveyor Systems
Intake objects from ground and move around with objects (Elevation)
Chains, belts, tank treads w/ zip ties, flaps
Claws Can grab almost
everything BUT... can only
grab one object at a time and harder to drive
Suitable for pneumaticso one motiono motor has to keep
runningo servo only moves
in desired positions
Fixed/Mechanical
Can do simple basic tasks without using a motor to do it (knocking down footballs, Green Eggs triangle goals)
Scoring Systems
4-Bar Linkage
Can raise manipulator at a constant angle Use 4 bars Need lots of torque to lift, esp. if heavy load
Elevators
Use sliders to lift loads vertically
Need to make sure low friction
Also need a lot of force
Arms/Basket/Dump
Can be used to reach a wide range of positions
Depending on placement of forces, loads, and fulcrum, may require a lot of torque to function
Shooter/Catapult Fire objects to
places cannot access
Need VERY HIGH RPM and enough torque to launch objects, heavier = harder
Catapult... Pneumatics may work depending on objects and distance needed to fire... CHEESYPOOFS!
Sensors
Limit Switch
Useful for making a limit on the arm's rotation, or for autonomous, determining if object is in claw
Potentiometer
Measures the angle of the shaft
Useful for autonomous or driver control for arms
Sources
http://media.wpi.edu/News/Events/Robotics/First/2008/Videos/
2008FRC_Mechanisms1_Collection_Ventimiglia.wmv
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