LEGO Mindstorms Robotic Invention System

1. LEGO Mindstorms Robotic Invention System Barb Ericson ericson@cc.gatech.edu Georgia Institute of Technology

2. What is it? • A kit for creating and programming robots built with LEGOs

3. What is in it? • 717 LEGO elements • One RCX programmable brick • 2 motors • 2 push sensors • 1 light sensor • Infrared transmitter for transferring the programs • A Constructopedia book with plans for 3 robots and many variations on them • CD with video on getting started and visual programming environment (RCX code) • 9 robots total

4. What else do you need? • 6 AA batteries • Computer • Windows 98/Me/XP • Pentium II 233MHz • 32 MB RAM • 115 MB Disk Space • USB Port (for the infrared transmitter)

5. What else might you want? • Plastic storage containers • For storing built robots • And for sorting parts better • Ultimate Accessory Kit - $50 • 45 LEGO pieces including • 1 remote control • 1 touch sensor • 1 rotation sensor • 1 lamp • 1 Constructopedia

6. More Sensors • http://www.legoeducationstore.com/catalog.cfm?dest=itempg&itemid=920&secid=9&linkon=subsection&linkid=45 Light Angle (Rotation) Touch Temp Touch

7. DCP Sensors • http://www.legoeducationstore.com/catalog.cfm?dest=itempg&itemid=922&secid=9&linkon=subsection&linkid=45

8. What else might you want? • Vision Command - $100 • A video camera • 30 frames per second • 352 by 288 color • 145 LEGO elements • USB connection • Built-in microphone • Vision recognition software • Or get just the camera and USB cable for $39.00 at LEGO Education Store

9. What does it cost? • About $200 • Buy at • Toys R Us • Shop.lego.com • Amazon.com • Wallmart.com • http://legomindstorms2.0.hobbytron.net/robotlegosub.html?source=1359 • Ebay.com

10. What can you do with it? • Use it with RCX code or Robolab (visual programming) • To teach about commands, programs, iteration, conditionals, and variables • Without worrying about syntax • Use it with leJOS (Java) • To teach about commands, programs, iteration, conditionals, and variables • Arrays, strings, recursion, listeners, static • Using Java syntax

11. Programming your Robot • Click the Program button in the main menu

12. Pick the Robot • Pick the robot to program. If you are using your own design pick “Freestyle”.

13. Create a Program using RCX code • Big Blocks are shown for a particular robot • Click and drag them to make a program • They will snap into place • You can save the program using the File menu • This will name your program

14. Download your Program • Turn on the RCX (OnOff button) • Plug the IR Tower into your computer • Put the RCX near the IR Tower • Click the “Download” button • The default is to download to slot 5 • You can change this by clicking on “Settings” • When the download is finished the RCX will play a short tune • It displays dots during the download

15. Running the Program • Two ways to run • Click the Run button on the RCX • Or click the Run button on the screen • Stopping the program • Click the Run button again on the RCX • Or click the Stop button on the screen

16. Modify a Block • Click on the edit tab at the right edge of the block • You can change the duration of commands • Use the arrow key to use preset values • Or type a value in the textbox

17. Robot Challenge • Make your robot go forward for 2 seconds • Make your robot turn right for 1.5 seconds • Make your robot go backwards for 3 seconds • Make your robot spin left for 1.5 seconds • Save your program using the File menu

18. Getting More Information • Click on Help • Click on What’s this? • The cursor will show What’s this? with an arrow • Click on something you want more information about • Like a block • Or a menu item

19. Robot Challenge • Use the help to find out the difference between turn left and spin left • Use the help to figure out what a Dance block will do • Use the edit tab to try out the Dance block • Make sure your robot is on and near the IR tower

20. Using the Sensors • Click a Touch Sensor on the left and position it on the right • Pick the input port attached to your sensor • Click next • Pick when to respond • On press, release, or click (press and release) • Click next • Click “Try It” to try it or “Done”

21. Handling a Sensor Event • Add command blocks after the if sensor event block • These actions will happen when that sensor event happens • Like when the touch sensor is pressed • Or when the light sensor’s value is > or < some amount

22. Robot Challenge • Make your robot go forward for 10 seconds • If your robot’s touch sensor is pressed backup for 1 second and spin right • Set up items to block your robot and try it

23. Adding Iteration • Use Repeat Blocks to add iteration (looping) • You can change the number of iterations • You can repeat a group of commands

24. Conditionals • Add a test • Do one thing if the test is true • Like turn left • Do something else if the test is false • Like turn right

25. Variables • You can create new variables • freq • And use them in other blocks • Add to them • Subtract from them • Multiply them • Divide them

26. Create New Blocks • You can create new blocks using My Blocks • Name the block • Add other blocks to it • You can collapse the interior commands • Click on upper left square

27. Small Blocks • Finer control of robot • Big Blocks are made up of small block commands • Click on the top left box to open a big block • And see the internal small blocks

28. Where to get help? • http://mindstorms.lego.com\ • Main web site • Books – at LEGO Education Store • Building Robots with LEGO Mindstorms • Creative Projects with LEGO Mindstorms • LEGO Mindstorms: RIS 2 Projects

29. Project Ideas • Anders Project ideas (scanner, fan) • http://www.norgesgade14.dk/legoSider/mindstorm_en.html • Andy’s Page (chess playing robot) • http://www.artilect.co.uk/lego/default.asp?page=Chess • Buick Music Study (Play MIDI or WAV files) • http://www.aga.it/%7Eguy/lego/bms.html • Joe’s Nagata’s Mindstorms Gallery (vehicles) • http://homepage3.nifty.com/mindstorms/ • http://members.at.infoseek.co.jp/Milano/studio1.html (movies) • Mario Ferrari’s Web Pages (piano player, skier, etc) • http://www.marioferrari.org/lego_mindstorm.html

30. Using Java with LEGO Robots • Install leJOS (the Java Operating System) • Download from http://lejos.sourceforge.net/faq.html • Set the system variables • Plug in the IR Tower to the top USB port • Download the firmware using a command prompt • lejosfirmdl

31. Setting System Variables • Create new System Variables • LEJOS_HOME variable to the directory where leJOS is installed • RCXTTY=USB • Add to the PATH variable • The Java SDK bin directory • ;%LEJOS_HOME%\bin • Add to the CLASSPATH variable • ;%LEJOS_HOME%/lib/classes.jar;%LEJOS_HOME%/lib/pcrcxcomm.jar

32. Using leJOS • Import the classes in leJOS • import josx.platform.rcx.*; • Compile for Java 1.1 using • lejosjc.bat Class.java • Link together an executable • lejoslink.bat -o Class.bin Class • Download the executable to the RCX • lejosdl.bat Class.bin

33. LCD Control

34. Motor Class • 3 objects are available as public static (class) variables • Motor.A, Motor.B, and Motor.C • You make the motor go forward, backward, stop (brake), and float to a stop • When you start a motor forward it will keep going until you tell it to stop or float to a stop. • Use Thread.sleep(numMilliseconds) to control how long the motor is moving • Control how fast the motor moves with • setPower(num) with num from 0 to 7 (fastest)

35. Motor Test • Make both A and C motors go forward at power 7 for 1 second • Stop for 1 second • Have both motors go forward at power 2 for 3 seconds • Float to a stop

36. leJOS Resources • Download from • http://lejos.sourceforge.net/ • Tutorial at • http://lejos.sourceforge.net/tutorial/ • Discussion at • http://sourceforge.net/mailarchive/forum.php?forum_id=552 • Books • http://lejos.sourceforge.net/books.html

37. FIRST LEGO League • Robotics competition for a team of kids (ages 9-14) • Up to 10 kids on a team • Register by Sept 30th • Work for 8 weeks on a challenge • New one each year • Compete at tournaments Nov – Dec • Georgia Tech hosted one Jan 15, 2005 • Cost (about $600 per team)