Learning Roomba

Module 2 - Robot Configurations

Outline

What is a Robot Configuration? Why is it important? Several types of Configurations Roomba Configuration

What is a Robot Configuration?

Describes how a robot can move and where it can go

Includes Physical shape of the Robot Model of how the Robot can move in the

Environment

What is a Robot Configuration?

Holonomic vs. Non-holonomic Holonomic Robots can move in any direction Non-holonomic Robot is contrained to certain

types of movement Example: A Car is non-holonomic

What is a Robot Configuration?

For ground robots, the Configuration often describes how it Rotates (How the robot turns) Translates (How the robot moves forward or

backward)

Why is it important?

With the Configuration you can tell how a Robot will operate prior to controlling it

Important to understand a Robot’s limitations while designing it

Several Types of Configurations Wheeled Robots

Differential Drive Ackerman Steer Tricycle Drive Synchro Drive Skid Steer Roller Wheeled

Legged Robots Flying Robots

Fixed-wing Rotorcraft

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Differential Drive

2 Wheels Independently powered in-line with each other Usually in the center of the

robot

Often has 1 or 2 casters Non-powered Swivel in any direction Add stability

Differential Drive

Advantage Simple Design Can go anywhere the robot

can fit

Disadvantage Has difficulty with uneven

terrain (both wheels need to touch the ground to work)

Has to rotate before traveling in a new direction

Differential Drive

Shape matters In this example, the Circle robot can turn freely while the

Square robot cannot

Ackerman Steer

Like a Car 4 Wheels

2 Rear wheel are powered, fixed-rotation 2 Front wheels are non-powered that turn

Turn at different Angles

Ackerman Steer

Advantage Drive and Rotation functionality are separated Typically more stable

Disadvantage Mechanically complicated Often complicated maneuvers (non-holonomic)

Tricycle Drive

Similar to Ackerman Steer Only 1 front wheel that turns

Tricycle Drive

Advantage Mechanically Simpler

Disadvantage Similar motion limitations as Ackerman Steer Less Stable

Synchro Drive

At least 3 wheels All rotate together All are powered together

Synchro Drive

Advantage Can travel in any direction without turning the top

base Separate motors for turning and driving

Disadvantage Very Mechanically Complicated Top base cannot face another direction

Skid Steer

Like a tank Several wheels on

each side or tank treads

Turning Requires skidding

Skid Steer

Advantage Can handle uneven

terrain well Disadvantage

Poor odometry due to skidding

Roller Wheeled

3 Wheels Arranged around the

circumference of the robot

Wheels are Roller Wheels (Next Slide)

Non-Steering Independently

Powered

Roller Wheeled

Roller Wheels Includes Rollers

Perpendicular to the Wheel

Around the wheel Non-powered

Roller Wheeled

Advantage Can go in any direction

without first rotating Can go anywhere the

robot can physically fit Disadvantage

Tracking position through odometry is difficult

Legged Robots

Uses legs instead of wheels Any number of legs

Legged Robots

Advantage Can travel over rugged terrain

Disadvantage Mechanically complicated Hard to control

Fixed Wing Aerial Like a Plane Not Restricted to the ground

Rotorcraft Aerial Like a Helicopter Not Restricted to the ground Can take-off vertically

Other Configurations Many other Configurations Robots are not restricted to Ground (or even Air) Can be manipulated in many different ways

Roomba Configuration Wheels

2 Wheels Independently Powered Non-Steered Arranged at approximately the

center of the robot on opposite sides of each other

Shape Circular Few inches tall

Roomba Configuration Round Differential-Drive

Configuration Can travel anywhere the

Roomba can fit and get to Can move in any direction,

but first need to turn to that direction

Questions?