Introduction to LEGO NXT robotics and Robot Sumo – Sept 20, 2008

Douglas G. CzinderIEEE SEM R&A Chairpersonchair@semrobotics.org

Professor Keith Bozinkbozin@greaybox.com

CJ Chung, Ph.D.Associate Professor and Director of Robofestchung@LTU.edu

Lawrence Technological University

This program is possible thanks to:

a grant from The Chrysler Foundation

the Southeastern Michigan Chapter of the IEEE Robotics & Automation Society

Workshop Schedule – Sept 20, 2008

9:30 – 10:00 Continental Breakfast (provided) 10:00 – 10:20 Intro to Lego NXT & Robofest 10:20 – 11:00 Basic NXTG programming 11:00 - 11:15 Break 11:15 - 12:30 Programming with Sensors

12:30 - 1:30 Lunch (provided)

1:30 - 2:15 Programming with Sensors (cont’d) 2:15 – 2:30 Break 2:30 – 3:00 Basic Sumo Program 3:00 – 3:30 Improved Sumo Program 3:30 – 4:00 Mini Competition

Introduction to Robotics

What is a true robot? autonomous robot with an on board computer Mechanical, electrical, and computational

components Six fundamental components of a robot

A brain or brains – computer Body: physical chasses that holds other pieces Actuators: motors, hydraulic pistons, pneumatics Sensors Power sources Communication mechanism

What is Robofest?

100% Autonomous Affordable Challenging: Unknown problem No direct adult help allowed during the

competition Qualifiers and a World Championship Various categories including Robot Sumo Two divisions:

5th – 9th grade: Jr. Division 9th – 12th grade: Sr. Division

RoboSumo

Push the other robot out of the Sumo ring

Specifications

  Junior Division Senior Division

Sumo ring diameter 77 cm (30 inches) 122 cm (48 in)

Maximum robot mass

1kg (2.2 lbs) 2 kg (4.4 lbs)

Maximum robot width and length

23 cm (9 inches)30 cm (11.75

inches)

Maximum robot height

no limit 30 cm (11.75

inches)

Robot type Any;Lego Mindstorms or NXT

recommended. any

Why Sumo?

The most popular robot competition in the world

Integrator in Science Education – Math, Logic, Computers, Mechanics, and Physics

Good for rookie teams Fun Motivator

Unknown Problem in Robofest Sumo

How to start is unknown Need sensor(s) Teams must bring a computer to program

the unknown parts

Introduction to Lego NXT

Brain – RCX micro computer Body: Lego Technic pieces Actuators: up to 3 motors Sensors: Light, Touch, Ultrasonic, Sound, etc. Power source: 9V (six AA batteries or

rechargeable battery pack) Communication mechanism: USB or Blue

Tooth

Introduction to “SB2 (Sumo Bot 2)”

Left motor: A Right motor: C Touch: 1 Light: 3 Ultra Sonic

(distance): 4

Introduction to NXTG Programming

Please go through Getting Started and Software Overview after this class

First NXT program: Go forward for 2 sec. and stop

Let’s name the program first

Click on Go >> button You’ll see a

programming palette (canvas)

First NXT program using SB1: Go forward for 2 sec. and stop (2/3)

Click on Move button Drag and drop the move block to

the canvas

First NXT program using SB2: Go forward for 2 sec. and stop (3/3)

Change parameters for the Move Port Direction Steering Power Duration Next Action

Block

Configuration Panel

How to run your first program (1/2)

How to run your 1st program (2/2)

If “Found New Hardware” pops up, just follow the instruction

Click on “Download” button Recommended to un-plug the

cable from the Bot Press the orange button 4 times

(Turn on, My files, Software files, Run your program entitled go2stop)

How to rerun the program

Check the program name on the LCD Press the orange button just once again

How to stop the program

Gray button

First NXT Program: Go forward for 2 sec. and stop (Review)

Do not forget:

Save your programs Meaningful file (program) names Use comments

2nd Program: ForwardBack

1. Go Forward 2 rotations2. Wait 3 seconds, then 3. Backward 1 rotation

Go Forward 2 rotations, Wait 3 seconds then Backward 1 rotation – ForwardBack

Making Turns(Instructor Slide)

Turn left

Spin left

Face left

Left wheel Right wheel

Left wheel Right wheel

Left wheel Right wheel

stop

stop

Objective Challenge the students to think about how a turn is made Two ways to turn using one motor (demonstrate by turning with

your leg) Demonstrate advantage of turning by spinning

Making Turns

Turn left

Spin left

Face left

Left wheel Right wheel

Left wheel Right wheel

Left wheel Right wheel

stop

stop

Forward 2 rotations, Turn Left 90 Degrees, and Forward 2 rotations

Turn90Left – Using a Motor Block!

Forward 2 rotations, Turn Left 90 Degrees, and Forward 2 rotations – Turn90Left

How do we make to turn 90 degrees?

Timer? Trial errors Let’s do the math!!!

Width of the robot: 14 cm Diameter of the wheel: 5.5 cm Perimeter of the wheel: 5.5 cm x pi = 17.27

Travel distance needed: (14 x 2 x pi) / 4 = 21.98 cm

Number of rotations needed?

21.98 / 17.27 = 1.272714 cm

Programming with Sensors

Programming with Touch Sensor Light Sensor Ultrasonic Sensor

Repeat Basic Sumo Program

Start-Touch

Wait until the touch sensor is pressed; Then start the robot to go forward Stop after a second

Start-Light

Locate the robot in the middle of the ring Wait until the light sensor detects very

bright (lantern) light Then start the robot to go forward Stop after a second

Start-Light

Stop-Touch

Go straight until the bumper is hit then stop

Stop-Edge

Go straight until the white edge of the ring

Then stop

Loop

To repeat a sequence of code Until

Elapsed time Number of repetitions Sensor condition is met Logic becomes true Forever

Say “Yes” – 10 times

Make the robot move around in the ring – Basic Sumo (Sumo0)

Repeat the following forever: Go forward until the edge Backward slightly Spin right

Sumo0

First Sumo Competition

Some matches Ask students to list ideas to improve the

Sumo robot

Improved Sumo Program

Improved Sumo program Unknown Problem Mini Competition Tips and Ideas to improve your Robot!

Program for the Mini Competition

Press “Shift” to connect parallel sequence beams

Ideas to improve your SumoBot

Improve (debug) your program! Applying Theories learned in Physical

Science Mass, Newton’s laws Friction Gearing Wheel size Power level

Detecting the opponent (can be done later) Touch sensor US sensor(s)

Ideas to increase weight of your Robot

What is the max weight of each division? Add more Lego technic pieces, if you

have some at home Add Coins, Used Batteries, or others –

make a holder using cardboards

Put your team name on the robot. An idea: make a team flag

Ideas to increase friction of your Robot

Use rubber bands Add more wheels later for Worlds

Gearing Ideas

Use gear train to increase gear ratio Considering resources, this is not allowed

for the school qualifier The winner from the school qualifier may

consider this idea later

Changing Wheels?

Using bigger wheels Considering resources, this is not allowed

for the school qualifier The winner from the school qualifier may

consider this idea later

Make sure the Power!

Default power level is 75% Fully charge your battery!!! How to check the voltage level?

See the icon on the LCD

Changing the shape of the Robot

Make it sturdy Front part may need some changes (After

the school qualifier)

Height of the robot matters?

Consider the “center of gravity”

Ideas using 2 Touch Sensors

A touch sensor –front leftAnother touch sensor – front right

If left sensor is pressed – turn left and push hard

If right sensor is pressed – turn right and push hard

If both left and right sensors are pressed, push straight hard

What is next? - Meet with your teacher at least twice before the school qualifier

Improve your programs Add stuff for the max possible weight for

your robot Review what you have learned for the

unknown problem. If you do not solve the unknown problem, you lose automatically

Signed Media Release form must be ready before the qualifying competition date at your school

Online Resources

www.ortop.org/NXT_Tutorial: a great tutorial on how to program in NXTG

nxtasy.org: with more information than you could ever want about LEGO robots and programming; a great place to ask questions

End of Today’s Workshop

Contact us with any questions:

Douglas G. Czinder IEEE SEM R&A Chairperson chair@semrobotics.org

Professor Keith Bozin kbozin@greaybox.com

CJ Chung, Ph.D. Associate Professor and Director of Robofest chung@LTU.edu