Transcript Robo Academy Mindstorms NXT with Java.docx, leJOS

MINDSTORMS NXT with JAVA
A guide to getting started
Berry Nall
Robotics Coach, Roma High School
I. Introduction
What is leJOS?
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“leJOS NXJ is a Java programming
environment for the LEGO MINDSTORMS
NXT ®. It allows you to program LEGO ®
robots in Java.”
http://lejos.sourceforge.net/nxt/nxj/tutorial/Preliminaries/Intro.htm
Why would educators use leJOS?
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Introduce students to text-based
programming
Inspire student interest in JAVA, a widelyused programming language
Allow students to take advantage of leJOS’
superior performance
At the 2011-12 TCEA Region One Advanced Arena competition, the top 3 robots
and at least 4 of the top 6 finishers were programmed using text-based
programming (leJOS or RobotC).
Other Advantages of leJOS
(compared to NXT)
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Faster loading and program execution
Programs use less memory
Greater accuracy
Scalable
Free!
Who can learn to use leJOS?
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Anyone here (and your students) can learn
enough to program for a TCEA competition.
We hope some of our students will go far
beyond what we can do.
II. Eclipse IDE
An Integrated Development Environment is a program
that allows you to write (and run) programs.
Uploading leJOS to the brick
If something goes wrong?
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The brick will most likely make a ticking
noise.
1. Reinstall the NXJ software using the
LEGO-supplied program.
2. Upload the leJOS software again.
Exploring Eclipse
Upload program
Locate program files
Edit program
Upload status
Eclipse helps
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In Eclipse, the view is called a “perspective.” Students may change it
accidentally, causing confusion.
This view is saved as the “leJOS” perspective.
Current perspective
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To restore, click “Window”, then choose “Reset
perspective”
Eclipse helps
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Eclipse tells you if there is a typing error or an
illegal command:
Eclipse helps
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Click here to load a program:
III. JAVA basics
JAVA Rules to remember
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Capitalization matters! Ex: tcea is not
TCEA is not tCeA
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Every command ends with a semicolon
// means you are inserting a comment;
everything after the slashes is ignored
IV. Writing programs
Program Sections
Import
statements
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File name
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Define pilot,
sensors
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import lejos.nxt.*;
import lejos.robotics.navigation.*;
import lejos.util.Stopwatch;
/**
*comment to name author (please change!)
*
*/
public class TCEA
{
//Variables and declarations go here
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public static void main(String[] args)
{
// program goes here
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}
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Commands
for robot to
follow
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}
To start: modify TCEA.java for your
robot
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Experimentally determine the wheel diameter.
Make the “travel” statement a comment and
remove the comment slashes from the “rotate”
statement.
Experimentally determine the wheel base. Note:
the wheel base may need to be modified for
different surfaces or designs even if the actual
size doesn’t change.
Test your robot:
TCEA1rectangle.java
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If the wheel diameter and wheelbase are
set correctly, the robot will travel in a
rectangle and arrive where it started.
To program your robot: save the
modified TCEA.java with a new name.
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Change the class to the name of your file.
Add commands to make the robot move.