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javabehaviorlego-mindstormslejos-nxj

usage of ev3 ultrasonic sensor in lejos behavior based programming

I'm using ev3 ultrasonic sensor. And I'm writing a behavior based lejos code. I want to do some tasks when the ultrasonic sensor detects an object which is not further than 30 cm's. And this is my code:

public UltrasonicSensor(Port port)
    {
        sonar = new EV3UltrasonicSensor(port);
        sonar.getDistanceMode().fetchSample(value, 0);
    }

    @Override
    public boolean takeControl() {
        // TODO Auto-generated method stub
        return value[0] < 0.3;

    public void action() {
        ....
    }

    @Override
    public void suppress() {
        // TODO Auto-generated method stub
        suppressed = true;
    }

But I think it is not the right way. How can I implement it in the right way?

Thanks for help,

Solution

  • It appears you are only fetching a distance sample from the ultrasonic sensor once. Get a SampleProvider object from the getDistanceMode(), store it in a global variable, and call fetchSample() on it each time you want a new sample.

    However, you may want to make sure that you don't ask the sensor for a new sample too often, as this may overload it with ping requests. Sound can be slow in comparison to how fast your program runs.