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