1 / 28

Using LeJOS

Using LeJOS. LMICSE Workshop August 11 - 14, 2006 Villanova University. Presentation Outline. LeJOS Overview An Example Program Controlling Motors Sleeping Using Sensors Generating Sounds Using Buttons Defining Listeners LeJOS Resources. LeJOS Overview. LeJOS

thibault
Download Presentation

Using LeJOS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Using LeJOS LMICSE Workshop August 11 - 14, 2006 Villanova University

  2. Presentation Outline • LeJOS Overview • An Example Program • Controlling Motors • Sleeping • Using Sensors • Generating Sounds • Using Buttons • Defining Listeners • LeJOS Resources

  3. LeJOS Overview • LeJOS • is an open source project • is based on a subset of Java with extensions for the RCX • missing Java features hard to predict (i.e., no switch statement) • contains as well some advanced robotics libraries • navigation (odometry) • behaviors (subsumption architecture) • image processing (vision) • is available at lejos.sourceforge.net

  4. import the basic LeJOS package set up a bump sensor sensor constants turn on the motors “poll” the sensor An Example Program import josx.platform.rcx.*; class GoForward implements SensorConstants { public static void main(String[] args) { Sensor.S2.setTypeAndMode(SENSOR_TYPE_TOUCH, SENSOR_MODE_BOOL); Motor.A.forward(); Motor.C.forward(); while( Sensor.S2.readValue() != 1 ) ; } } Move forward until a bump

  5. Controlling Motors • Three Motors: A, B, C • Controlled using: • public static void forward() • public static void backward() • public static void reverseDirection() • public static void flt() • public static void stop() • public static void setpower()

  6. Motor Examples • Motor.A.forward(); • Motor.B.forward(); • Motor.B.flt();// like an idle • Motor.A.reverseDirection(); • Motor.A.setPower(3);// possible values 1-7 • (deceptive – does not cause the motor to go slow it just causes to use less energy which, perhaps, might slow it down)

  7. threads can be interrupted timing is in milliseconds Sleeping • Put the thread to sleep in order to time movements import josx.platform.rcx.*; class Patrol { public static void main(String[] args) throws InterruptedException { Motor.A.forward(); while (true) { Motor.C.forward(); // go forward Thread.sleep (5000); Motor.C.reverse(); // turn around Thread.sleep (1000); } } Patrol back and forth

  8. Using Sensors I • Three Sensors: S1, S2, S3 • First you must “set type and mode” of the sensor • setTypeAndMode(int aType, int aMode) • use the SensorConstants for aType and aMode: aType SENSOR_TYPE_RAW = 0; SENSOR_TYPE_TOUCH = 1; SENSOR_TYPE_TEMP = 2; SENSOR_TYPE_LIGHT = 3; SENSOR_TYPE_ROT = 4; aMode SENSOR_MODE_RAW = 0x00; SENSOR_MODE_BOOL = 0x20; SENSOR_MODE_EDGE = 0x40; SENSOR_MODE_PULSE = 0x60; SENSOR_MODE_PCT = 0x80; SENSOR_MODE_DEGC = 0xa0; SENSOR_MODE_DEGF = 0xc0; SENSOR_MODE_ANGLE = 0xe0;

  9. Using Sensors II • Sensor.S1.activate();// turns the sensor on • Sensor.S1.passivate();// turns the sensor off - required for “active” sensors

  10. Sensor Examples • Sensor.S2.readRawValue(); (must be used if aType = 0) • Sensor.S2.readBooleanValue(); (used if aMode = BOOL e.g. touch sensor) • Sensor.S2.readValue(); (used for light sensor percentage aMode = 3 aType = 0x80)

  11. light sensors must be activated use the LCD class for display Sensor Code Example import josx.platform.rcx.*; class LCDShowLight implements SensorConstants { public static void main(String[] args) { Sensor.S1.setTypeAndMode(SENSOR_TYPE_LIGHT, SENSOR_MODE_PCT); Sensor.S1.activate(); while(true) LCD.showNumber(Sensor.S1.readValue()); } } Repeatedly display the reading of the light sensor

  12. Sound • Uses RCX speaker – useful for debugging • beep() // one beep • beepSequence() // a series of beeps going down • buzz() // a buzz • playTone(int aFrequency, int aDuration) • aFrequency: 31-2100 Hz //human sound range • aDuration: 1 – 256 Centiseconds

  13. ascending descending Sound Code Example import josx.platform.rcx.*; class AudibleSounds { public static void main(String[] args) throws InterruptedException { for(int f = 440; f < 10000; f = 110*f/100) { LCD.showNumber(f); Sound.playTone(f, 50); Thread.sleep(500); } for(int f = 440; f > 20; f = 90*f/100) { LCD.showNumber(f); Sound.playTone(f, 50); Thread.sleep(500); } } } Play an ascending and then a descending series of tones

  14. The RCX Buttons • All buttons may be re-programmed except “RUN” • Controlled by a “button class” • Polling or Using a Listener (Discuss) • “listener” or directly using waitForPressAndRelease()

  15. blocks until button click Button Code Example import josx.platform.rcx.*; public class RunButton { public static void main(String[] args) throws InterruptedException { // move forward Motor.A.forward(); Motor.B.forward(); // just run until RUN button is pressed again Button.RUN.waitForPressAndRelease(); } } Move forward until RUN button is pressed

  16. Using Listeners • Just as with standard Java, you can define listeners. • Perhaps most useful with sensors, particularly touch sensors. • You need to • implement the SensorListener interface by defining a stateChanged method. • register the listener with the appropriate sensor(s).

  17. Listener Example • An extended example: • The robot patrols back and forth. • While it patrols, it plays (without stopping) • a low tone when its left bump sensor is pressed. • a high tone when its right bump sensor is pressed.

  18. implement SensorListener can’t register a listener in a static object register the listeners Listener Example Part 1 import josx.platform.rcx.*; class ListenerExample implements SensorConstants, SensorListener { public static void main(String[] args) { ListenerExample exam = new ListenerExample(); Sensor.S1.setTypeAndMode(SENSOR_TYPE_TOUCH, SENSOR_MODE_BOOL); Sensor.S3.setTypeAndMode(SENSOR_TYPE_TOUCH, SENSOR_MODE_BOOL); Sensor.S1.addSensorListener(exam); Sensor.S3.addSensorListener(exam); exam.patrol(); } The beginning of the class definition and the main method

  19. sleeping does not affect the listener Listener Example Part 2 public void patrol () { try { Motor.A.forward(); while (true) { Motor.C.forward(); Thread.sleep(3000); Motor.C.backward(); Thread.sleep(1000); } } catch (Exception e) { } } The patrol method

  20. on a press, not a release id is either 0, 1, or 2 Listener Example Part 3 public void stateChanged(Sensor source, int oldValue, int newValue) { if (newValue == 1) if (source.getId() == 0) // left bumper Sound.playTone(220, 50); else if (source.getId() == 2) // right bumper Sound.playTone(660, 50); } }// end class ListenerExample The stateChanged method and class definition end

  21. Where to Learn More • The LeJOS Tutorial: an online resource which is part of the LeJOS project. • Books such as: • Core Lego Mindstorms Programming, by Brian Bagnall (Prentice-Hall, 2002), • Programming Lego Mindstorms in Java, by Giulio Ferrari, et al (Syngress, 2002), • and many others.

  22. The BlueJ IDE and MindStorms • A popular integrated development environment for Java developed by Michael Kolling and others • Often used in introductory CS courses • Available at www.bluej.org, easy to install • Go ahead and open BlueJ on your PC

  23. Setting up BlueJ for MindStorms • Two requirements: • Install LeJOS • Available from lejos.sourceforge.com • Just do the basic install • Add the BMJT plugin to BlueJ • Available from ddi.uni-paderborn.de/mindstormstools/bjmt • Good instructions available online • These steps are already done for you on your PC!

  24. set the path to the JDK set the path to LeJOS choose configure just say usb there is a 1.5 option in newer versions Once the BMJT Plugin is installed • You need to configure it • This is already done for you on your PC!

  25. choose firmware Firmware • Now you can download the firmware to the RCX • Plug the tower into a usb port • if on a PC you may need to install the usb drivers • Place the RCX in front of the tower, turn it on • ChooseFirmware • You will see a progress dialog on the PC • On the RCX you will see an ascending series of numbers

  26. choose compile not this one! Compiling an Existing File • Right-click (Command-click) on the file icon • ChooseCompile from the pop-up menu

  27. choose download Downloading a Project • Robot must be on and in front of tower • Right-click (Command-click) on the file icon for the main class • ChooseDownload from the pop-up menu

  28. Try it Out! • Place the robot in its play area. • Press run. • It should move forward until it hits an obstacle.

More Related