Building Mindstorms NXT Building Mindstorms NXT RobotsRobots

Dr. David JohnsonDr. David Johnson

School of ComputingSchool of Computing

What Is a Robot?What Is a Robot?

Resources for Learning About RobotsResources for Learning About Robots

• Web– Wikipedia

• http://en.wikipedia.org/wiki/Robot– New Scientist

• http://www.newscientist.com/article/dn9973-instant-expert-robots.html

– Youtube• Many!

– MAKE magazine– Boy Scout badge guide is quite nice and cheap

• Consider exercising your team’s FLL skills by having them look at some of these resources

Some Example RobotsSome Example Robots

• Big Dog– http://www.youtube.com/watch?v=b2bExqhhWRI

• Planetary Exploration– http://www.youtube.com/watch?v=nb2GsD7TAjU&feature=related

• Home assistance– http://www.youtube.com/watch?v=GTxW3GWZ5hI

• Hobby– http://www.youtube.com/watch?v=zX09WnGU6ZY

What Is a Robot?What Is a Robot?

• Sense– Update information about the world

• Plan– Modify original plan in response to this

sensed information

• Act– Move in the world or make a change in the

world

Mindstorms NXTMindstorms NXT

• Can it?– Sense– Plan– Act

Mindstorms NXTMindstorms NXT

• It can– Sense

• Light intensity and color• Sound intensity• Button presses• Distance to nearby objects• Wheel revolutions

– Plan– Act

Mindstorms NXTMindstorms NXT

• It can– Sense– Plan

• Small computer brain– “the brick”

• Graphical programming language

– Act

Mindstorms NXTMindstorms NXT

• It can– Sense– Plan– Act

• Three motors that turn

Goals For TodayGoals For Today

• Raise your comfort level with Mindstorms– Building– Programming– There is no substitute for doing it

• Try some common tasks– Wheeled robot– Respond to sensors

• Maybe a taste of competition…

Testing EquipmentTesting Equipment

• Plug in motors, sensors

• A critical thing to know is the view program– Let you read values from

sensors without writing a custom program

BuildingBuilding

• Not “normal” LEGO pieces– Based on the Lego Technic build system– Pegs and holes

• Can be frustrating– Stable

• One peg makes a rotary joint• Multiple pegs lock two pieces in place

– Strong• Keep in close to the main body• The wheel axes must not be wobbly and flex!

Building ResourcesBuilding Resources

• There are lots of instructions for building things online– http://www.nxtprograms.com/– Have the team try some out

• Learn things that work• Then modify

– Don’t get too distracted with NXT guitars, guns, etc.

– 5 minute bot• A quick base• Probably not good to adapt for

competition

ProgrammingProgramming

• Programming teaches– Breaking complex problems into solvable parts– Precise thinking and specification– Creative experimentation to discover and isolate

problems

• Programs are designed on a base computer– Downloaded by USB cable to the brick

•

Programming the BrickProgramming the Brick

• LEGO Mindstorms NXT– Default language for programming Mindstorms

• Designed to be friendly– Nice tutorials

• Try them with your team

– Not based on traditional programming languages– Easy to do very basic things

• More difficult to advance• It does have some subtle actions that can cause confusion

Learning to Use the TutorialLearning to Use the Tutorial

• Each tutorial is structured as– Challenge– Build– Program

• The mobile base from the tutorials is not my favorite– Takes too long to build– Difficult to modify

A Quick Programming Tour A Quick Programming Tour

• Control goes along the path

• Each block performs some action– Most blocks are very flexible– Learn the options at the bottom panel– Many actions continue until

• A sensor is triggered• Time has passed• A commanded result is finished

A Quick TestA Quick Test

• Attach a motor to the brick (ports A,B,C)• Attach a touch sensor to the brick (ports 1,2,3,4)• Write a program

– Move block• Set duration to unlimited

– Wait until touch– Move block

• Set the brakes

• Download to brick• Run it

Additional ResourcesAdditional Resources

• There is a lot to learn, but you can get started pretty quickly

• I recommend– Winning Design! LEGO Mindstorms NXT: Design

Patterns for Fun and Competition• Most FLL-centric of the books• Beginning to medium skill level

– If you don’t have prior experience, I think you would be foolish not to look at this book.

• Parts of my FLL camp notes– More for getting a novice team started

Let’s have a competition!Let’s have a competition!

• Go through maze• Stop before unknown finish “wall”

• How to solve?– Detect or dead reckoning

• Development cycle– Build, test, adjust, repeat– Most kids do not understand how to test and

modify something until it works

Teams!Teams!