Motors at the same time

[ale252]

Hello,

I'm very new in programmation, but I'm tying.

I have a problem, I can Start the two motors at the same time with a while. He can stop when he is 20 cm from anything, but it doesn't stop the 2 motors at the same time, I have one stop et another stop. The robot do a little rotate.

Anybody know whats the problem?

I have this class:

Code: Select all

public class Moteur {

    public Moteur() {
    }

    public void avancer() {
        Motor.A.forward();
        Motor.B.forward();
       
    }

    public void reculer() {
        Motor.A.backward();
        Motor.B.backward();
    }
    public void tournerGauche(){
           Motor.A.rotate(320);
    }
   
        public void tournerDroite(){
           Motor.B.rotate(320);
           Motor.A.stop();
    }
}

And this other:

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public class HelloWorld {

    private static int dist = 20;

    public static void main(String[] args) {
        Moteur m = new Moteur();


        MotorPort a = MotorPort.A;
        UltrasonicSensor u1 = new UltrasonicSensor(SensorPort.S2);
        while (u1.getDistance() != dist) {
            m.avancer();

        }

        Motor.A.stop();
        Motor.B.stop();
        }
   

    }
}

Thanks very much for the help!

[roger]

The difficulty is that

Code: Select all

    Motor.A.stop();

does not return immediately, and Motor.B continues to run for a short time.
To make them stop simultaneously, you use

Code: Select all

Motor.A.stop()true;
     Motor.B.stop();

In your main() method, I do not think that
MotorPort a = MotorPort.A;
does anything useful. And the repeated call to
m.avancer();
is not necessary and should be removed. Every time a call is made to a motor method, the motor regulator thread, which is trying to control the motor speed, is reset which prevents it from doing its job.
Cheers,
Roger

[ale252]

Thank you very much, that help me!

Now it work correctly!

[ale252]

Do you know how to do to rotate exactly 90°? Because using the commande

motor.rotate(320);

It's not very exactly.

Thanks

[roger]

Hi
Yes, an accurate rotation of the robot is not so easy to achieve. You could try other values of the motor rotation to see what works best.
Now that you understand how the Motor class works, look at the DifferentialPilot class. You can use it to make your robot to rotate, travel forward and backward, and trace an arc of a circle. You can use the immediate return flag in these methods and use the ultrasonic sensor to stop the robot if it detects an obstacle while the robot is moving.
Good luck,
Roger