problem with Motor.A.rotate();

[treeface99]

Hi,

I am having trouble rotating the motors 80 degrees.. I am making a blackjack playing nxt robot and am having trouble with my card reading class. This class uses the Lego RGB colour sensor to read two coloured strips on the playing cards. Here is my code for the early stages of my ReadCard class :

import lejos.nxt.*;
import lejos.robotics.Color;

public class ReadCard {



public int CardRead(){

int counter = 0;

String colorNames[] = {"Red", "Green", "Blue", "Yellow",
"Megenta", "Orange", "White", "Black", "Pink",
"Grey", "Light Grey", "Dark Grey", "Cyan"};


while (!Button.ESCAPE.isPressed() && counter == 0)
{


ColorSensor colours = new ColorSensor(SensorPort.S1);
ColorSensor.Color colourVal = colours.getColor();


Motor.A.setSpeed(540);
Motor.B.setSpeed(540);
Motor.C.setSpeed(540);

Motor.A.forward();
Motor.B.forward();
Motor.C.forward();



if (colourVal.getColor()<7){

counter = 1;
Motor.A.rotate(80);
Motor.B.rotate(80);
Motor.C.rotate(80);

}

}


return card;

}

}

The aim of this is to turn the motors to draw in the card and when the sensor senses the beginning of the card, I want all 3 the motors to rotate 80 degrees to position the card in the correct position for the first coloured strip to be read. Everything works until the 'rotate motor' code runs. All that happens is one motor turns slowly for a few seconds then shuts off. If I remove the B and C line and just have Motor.A.rotate(80), it works and motor A rotates 80 degrees. I cant seem to get all 3 motors to rotate 80 degrees.

Any Suggestions?

Many Thanks

[kirkpthompson]

Try using a Motor.[A/B/C].stop() or .flt() between the.forward() and .rotate() transition and report back what the behavior is.

i.e.

Code: Select all

if (colourVal.getColor()<7){
    Motor.A.stop(true);
    Motor.B.stop(true);
    Motor.C.stop(false);
    counter = 1;
    Motor.A.rotate(80);
    Motor.B.rotate(80);
    Motor.C.rotate(80);
}


Best,
-K

[gloomyandy]

Do you really intend to let motors B and C continue moving forward while motor A rotates by 80 degrees. The rotate method waits for the rotation to complete, if you want to just start the operation use the non blocking version. You should probably also move the creation of the color sensor object, and the calls to setSpeed and to forward outside of the loop. Constantly calling these methods is not a good idea...

Andy

[treeface99]

thanks a lot for your input. I tried :

Code: Select all

if (colourVal.getColor()<7){


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

         
                        
            Motor.A.rotate(80);
            Motor.B.rotate(80);
            Motor.C.rotate(80);

            counter = 1;
}

This was a little closer to what i am aiming for. Now they perform a 80 degree turn, one at a time. What i need is for all 3 motors to turn 80 degrees at the same time.

I will play around with the creation of the colour sensor object and the setting of speed.

Many Thanks

[gloomyandy]

As I said above, you need this version of rotate:
http://lejos.sourceforge.net/nxt/nxj/api/lejos/nxt/NXTRegulatedMotor.html#rotate(int,%20boolean)
The one you are using will wait for the rotate to complete. Note that you may need to add code after the loop to wait for all three motors to reach the end point (see the waitComplete method)...

Andy

[treeface99]

thats great, working now. Thanks very much