Programming for Lego Mindstorms using Eclipse to take you back to your childhood!

Programming forLego® Mindstorms™using Eclipseto take you back to your childhood!
Benjamin CabéOct 28th, 2009

Agenda
The Mindstorms NXT brick
The LeJOS VM
Eclipse + Mindstorms = FUN!
Implementing an RSE connector
Data visualization inside an Eclipse editor
State machines modeling and code generation
©2009 Sierra Wireless inc. – Made availableunderEPL v1.0

The NXT brick
32-bit ARM7 processor @48MHz
256kB of Flash
64kB of RAM
100x64 pixel LCD display
USB 2.0
Bluetooth
Open Source firmware!

4 input ports

3 output ports (motors)

LeJOS NXJ VM
A tiny (10kb) but stillcool Java VM
Threads / Synchronization
Exceptions
Most of the java.lang, java.util and java.io classes
Generics, enums, « for each » loops
A “robotics”, event-based, API
Open Source!
Limitations
No GarbageCollector
No switch()

LeJOS NXJ Eclipse plug-in
Useful to upload firmware and/or programs to the brick
Not much integrated in the IDE…
… how about leveraging DSDP/TM?!

TM/RSE hacking
LeJOS NXJ comes with APIs to :
List/get/send files
Execute programs
Get sensor states
… it should be possible to define an RSE connector and a file subsystem…!

Brief RSE introduction
A frameworkat Eclipse to connect to remotesystems and provide:
remote file systems through SSH, FTP, a dedicated agent, or whatever
remote shell access
remote process monitoring
remote debugging (gdb)
It comeswithgeneric, reusable, UI

TM/RSE hacking (2)
In a couple of hours:
A new 'LeJOS' system is available
An RSE file 'subsystem' allows to:
Browse the brick's filesystem
Remotely execute programs
Another subystem could bewritten to retrieve sensors values
Nota: Communication with the brick can be done using either BT or USB

TM/RSE hacking (3)
Very straightforward 1..1 mapping between RSE and LEJOS APIs
Example: LejosRemoteFile implementation
publicvoid launch() throwsIOException {
LejosConnectorService connector = (LejosConnectorService) getParentRemoteFileSubSystem()
.getConnectorService();
connector.getComm().startProgram(_hostFile.getName());
}
RSE
LEJOS

Let’stoy a cool sonar!
Follows a closed track
Scans the interior of the track with the ultrasonic sensor
Writes a binary output file into flash memory
The file will be retrieved using the RSE connector

Robot behavior

Robot Java program
publicstaticvoid main(String[] args) {
tachoNav= new TachoNavigator(5.6f, 11.5f, Motor.A, Motor.B);
File fRadar = new File("result.radar");
FileOutputStream fosRadar = new FileOutputStream(fRadar);
tachoNav.goTo(0, TERRAIN_WIDTH, true);
while(tachoNav.isMoving()) {
intdist = ultrasonic.getDistance();
fosRadar.writeInt(dist);
}
}

Display captured data
In an Eclipse editor associated to .radar files
Parse binary files
Process signal
sin(α)… cos(α)… Remember?! 
Since the ambient noise level is also recorded, we can display it in a similar manner
http://www.sxc.hu/photo/1099687

17
State machines modeling
LeJOS comes with an event-based robotics API, remember?
Eclipse has a bunch of cool modeling/diagramming/code generation technologies
… how about mixingboth?!

18
LeJOS Visual Development Toolkit
A state machine framework on top of LeJOS
A GMF editor
Xpandtemplates for code generation
An integrationwith the LeJOS Eclipse plugin
Auto-deployment of the binary
Communication between the brick and the IDE to monitor the state machine

A state machine diagram…

Questions?
Benjamin Cabé
BCabe@sierrawireless.com

If youwannaplay by yourself!
http://www.mindstorms.com
http://lejos.sourceforge.net
http://www.juanantonio.info/p_articles/archive/2008/leJOSStatemachineDevelopmentToolkit.pdf
http://www.eclipse.org/dsdp/tm/