MINDSTORMS CATERPILLAR

I enhanced the code a little bit that the cat can move without seriously hitting any objects. It is steered by the ultrasonic-, touch- and light sensor. I wrote a Java class to let the cat find a black spot by avoiding barriers. It’s kind of an ad hoc code, I’ll optimise it during the next days and will let it look a bit more organised.

After reorganising the code I think it’s a good basis to add more intelligence to it, maybe something for remembering the route and optimising the path.

But for now it does it’s job:



Java class:

package tospinout;

import lejos.nxt.*;

/**
* 2008-12-27 author 2spinout
*/

public class Cat
{
static TouchSensor ts = new TouchSensor(SensorPort.S3); //initialize Touchsensor
static UltrasonicSensor us = new UltrasonicSensor(SensorPort.S4); //initialize Touchsensor
static LightSensor ls = new LightSensor(SensorPort.S2); //initialze Lightsensor

//drive train
public static void main (String[] aArg)
throws Exception
{
// PortA = Motor.A = ultrasonic movement motor
// PortB = Motor.B = left driving motor
// PortC = Motor.C = right driving motor
// Port1 = SoundSensor
// Port2 = LightSensor
// Port3 = TouchSensor
// Port4 = UltrasonicSensor

LCD.drawString("2spinout",3,4);
Thread.sleep(2000);
ls.setFloodlight(true);

for(int COUNT = 0 ; COUNT < 20 ; COUNT += 1)
{
int stop = 0;
int light = 100;

Motor.A.setSpeed(400);
Motor.B.setSpeed(400);//720=2RPM
Motor.C.setSpeed(400);
Motor.B.forward();
Motor.C.forward();
Thread.sleep(1000);

do {
LCD.drawString("--> forward",3,4);
for(int count2 = -90 ; count2 < 91 ; count2 +=45)

{
light = ls.readValue();

if ((us.getDistance() < 45)|| (Motor.B.getActualSpeed() <390) || (Motor.C.getActualSpeed() < 390)||(light < 40)||(ts.isPressed()==true))

{
Motor.B.stop(); //stop driving engines
Motor.C.stop();
stop = 1;
}
Motor.A.rotateTo(count2);
}

Motor.A.rotateTo(0);
if (light<40)
{
break;
}

} while(stop != 1);

if (light<40)
{
break;
}
Thread.sleep (1000);


//turn back
Motor.B.setSpeed(400);//720=2RPM
Motor.C.setSpeed(400);
Motor.B.backward();
Motor.C.backward();
LCD.drawString("<-- backward",3,4);
Thread.sleep (1000);
Motor.B.stop(); //stop driving engines
Motor.C.stop();
Thread.sleep (1000);

//find best way / best distance
int left = 0;
int right = 0;

//check left
Motor.A.rotateTo(-90);
left = us.getDistance();
Thread.sleep(500);

//check right
Motor.A.rotateTo(90);
right = us.getDistance();
Thread.sleep(500);

Motor.A.rotateTo(0);
Thread.sleep(500);

if (left>right)
{
//turn left
Motor.B.setSpeed(400);//720=2RPM
Motor.C.setSpeed(400);
Motor.B.backward();
Motor.C.forward();
LCD.drawString("-^ turn left",3,4);
Thread.sleep (1200);
Motor.B.stop(); //stop driving engines
Motor.C.stop();
Thread.sleep(1000);
}

else
{
//turn right
Motor.B.setSpeed(400);//720=2RPM
Motor.C.setSpeed(400);
Motor.B.forward();
Motor.C.backward();
LCD.drawString("-v turn right",3,4);
Thread.sleep (1200);
Motor.B.stop(); //stop driving engines
Motor.C.stop();
Thread.sleep (1000);
}

}

ls.setFloodlight(false);

}
}

NXT GOES JAVA

Due to the limited possibilities you have with the Lego Mindstorms software I just converted to the leJOS Java Virtual Machine and also flashed the NXT brick with the corresponding firmware.
I think it will give me much more options in coding functionalities. In addition to that I’m using the Eclipse JDK. The firmware flashing and installation of the leJOS was very quick but I have to admit that the correct Eclipse setup took quite a while. It’s just because I never used it before.
As this is all done now I’ll set up the first projects. Below you’ll find my first sample:

package tospinout;

import lejos.nxt.*;

/**
* 2008-12-26 author 2spinout
*/

public class Cat
{

public static void main (String[] aArg)
throws Exception
{
// PortA = Motor.A = ultrasonic movement motor
// PortB = Motor.B = left driving motor
// PortC = Motor.C = right driving motor
// Port1 = SoundSensor
// Port2 = LightSensor
// Port3 = TouchSensor
// Port4 = UltrasonicSensor

LCD.drawString("2spinout",3,4);
Thread.sleep(2000);

Motor.B.setSpeed(720);// 2 RPM
Motor.C.setSpeed(720);
Motor.B.forward();
Motor.C.forward();


Thread.sleep (5000);
Motor.B.stop();
Motor.C.stop();

}
}

MINDSTORMS

I’ll try a project with Lego Mindstorms during the next weekends. I ordered a book that should teach me how to code the NXT model with Java. I’m looking forward to the results. As motivation I already played a little bit: