LeJOS Java for Lego RCX. 2-12-2005. CJ Chung. Associat

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LeJOS Java for Lego RCX2-12-2005CJ
ChungAssociate Professor of Computer
ScienceDirector of Robofest AssistantsMauric
e TedderSteven KryskallaRick Dudley
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Agenda

• 900 am - Introduction to LeJos Java Programming
  using Eclipse
• 915 am Installation of Java, Eclipse, and
  LeJos
• 945 am LeJOS Java Programming Workshop
• 1100 am Mini Challenge
• 1145 am - Wrap-up

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Why Autonomous Robots?
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2 Million Dollar Prize, 2005
142 Miles, within 10 hours
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Weaponized robot, also known as SWORDS in Iraq,
Jan. 14, 2005
Many of the vehicles being developed will have
some autonomy, meaning they'll navigate rough
terrain, avoid obstacles and make decisions about
certain tasks on their own
The Pentagon's research arm, the Defense Advanced
Research Projects Agency, also recently awarded
contracts to aid research of robots that one day
could be dropped into combat from airplanes
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Your RJ (Roverbot Jr.)

• Two motors
• Left A
• Right C
• One light sensor on input port no. 1
• One touch sensor on input port no. 2
• One brain H8 microprocessor, 16MHz

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Why Java to program the Brain?
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Why Java?

• Write Once, Run Anywhere
• AP CS A and AB using Java since 03-04 year
• Pure OO (Object Oriented) language
• Standardized
• Free

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Characteristics of Java

• Simple automatic memory allocation and garbage
  collection. of language Construct is small.
• Portable
• Robust (Reliable) exception handling
• Multithreaded
• Interpreted
• Distributed
• Secure
• Architecture Neutral
• Dynamic You can freely add methods in a class at
  runtime)

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LeJOS for Lego

• LeJOS Ley-J-oss
• http//lejos.sourceforge.net
• Replacement Firmware for Lego RCX brick JVM for
  RCX
• Size 16KB
• around 12 KB for user-programs
• Download for Free
• Can be thought of as J2ME (Java 2 Micro Edition)
  for smaller devices such as pagers, cell phones,
  and handheld PCs.

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LeJos Memory Map
Routines for ROM (4 KB)
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Advantages of using Java for Lego instead of NQC
(or C)

• Pure Object Oriented. Enormous APIs
• Floating point numbers vital for navigation
• Recursion
• Threads
• Simple Event Model
• You can use custom made sensors, easily
• Powerful networking APIs
• Web control of your robot
• Everything is for free
• However, no Garbage collection yet (?)

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Comparing RCX programming languages
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How to Install LeJos programming environment

• Using DOS
• Start Control Panel System Advanced
  Environment Variables
• Add c\lejos\bin to the system PATH, if leJos was
  installed at c\lejos
• IDE
• Eclipse the best free Java tool
• www.robofest.net resources button

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Uploading JVM to RCX using DOS

• Fast mode lejosfirmdl f
• Slow mode lejosfirmdl
• It takes about one minutes
• After the download, you should see a number on
  the LCD representing the battery voltage

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Compile, Upload, and Run using DOS

• Compile lejosc ltfilenamegt.java
• Upload lejos ltfilenamegt
• Press the green button
• Uploading more than one program
• lejos ltfilenamegt,ltfilenamegt

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Workshop Topics

• Eclipse programming environment
• Learning Java Basics with Lego RCX
• Repetition while and for
• Decision if, if else
• Methods
• Variables
• Sensors
• IR Packet Communications
• Mini Challenge a part of Robofest Challenge,
  RoboRelay

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Robofest 2005

• Junior Division (5-9th)
• Senior Division (9th-12th)
• Exhibition Division
• 13 regional competitions
• Top winning teams to World Robofest at LTU on
  April 23.
• MPC laptops to the best team for each division

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Class Mission 1

• Do forever
• Beep when the light sensor sees the bright light

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Class Mission 2

• Go forward until the robot detects the edge of
  the white board. Stop at the edge of the board

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Class Mission 3

• Go forward while counting N black lines. Stop
  right after the Nth black line

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Mini Challenge (a part of Robofest Game)

• Start when the lamp under the board is on
• Follow the black line until it detects the end of
  the line (edge detection)
• Turn around
• Coming back to the home base
• Stop when the bumper (touch senor) is hit