Sensor lokasi

Sensor lokasi, atau GPS, memberikan posisi robot dalam meter. Pada robot pemula, namanya gps. Kamu membutuhkannya untuk melaporkan penanda dinding, dan sensor ini sangat membantu untuk menjelajah secara sistematis.

getValues() mengembalikan [x, y, z]. X dan Z adalah sumbu horizontal, dan Y vertikal, jadi gunakan X dan Z untuk posisi di labirin:

Python

from controller import Robot

robot = Robot()
timeStep = int(robot.getBasicTimeStep())

gps = robot.getDevice("gps")
gps.enable(timeStep)

while robot.step(timeStep) != -1:
    x, y, z = gps.getValues()  # In meters. X and Z are horizontal, Y is vertical.
    print("x:", round(x, 3), "z:", round(z, 3))

C/C++

#include <iostream>
#include <webots/Robot.hpp>
#include <webots/GPS.hpp>

using namespace webots;
using namespace std;

int main() {
  Robot *robot = new Robot();
  int timeStep = (int)robot->getBasicTimeStep();

  GPS *gps = robot->getGPS("gps");
  gps->enable(timeStep);

  while (robot->step(timeStep) != -1) {
    const double *position = gps->getValues(); // In meters. X and Z are horizontal, Y is vertical.
    cout << "x: " << position[0] << " z: " << position[2] << endl;
  }

  delete robot;
  return 0;
}

GPS memiliki derau (noise) beberapa milimeter, jadi nilainya sedikit berubah bahkan saat robot diam. Jangan pernah membandingkan apakah dua posisi sama persis.

Contoh: jarak dari titik awal

Program ini membuat robot maju sampai berjarak setengah ubin dari tempat awalnya:

Python

from controller import Robot
import math

robot = Robot()
timeStep = int(robot.getBasicTimeStep())

gps = robot.getDevice("gps")
gps.enable(timeStep)
leftWheel = robot.getDevice("left wheel motor")
rightWheel = robot.getDevice("right wheel motor")
leftWheel.setPosition(float("inf"))
rightWheel.setPosition(float("inf"))

robot.step(timeStep)  # Step once, so that the GPS has a value
startX, _, startZ = gps.getValues()

leftWheel.setVelocity(3.0)
rightWheel.setVelocity(3.0)

while robot.step(timeStep) != -1:
    x, _, z = gps.getValues()
    distance = math.sqrt((x - startX) ** 2 + (z - startZ) ** 2)
    print("Distance from the start:", round(distance, 3), "m")
    if distance > 0.06:  # Half a tile
        leftWheel.setVelocity(0)
        rightWheel.setVelocity(0)
        break

C/C++

#include <iostream>
#include <cmath>
#include <webots/Robot.hpp>
#include <webots/GPS.hpp>
#include <webots/Motor.hpp>

using namespace webots;
using namespace std;

int main() {
  Robot *robot = new Robot();
  int timeStep = (int)robot->getBasicTimeStep();

  GPS *gps = robot->getGPS("gps");
  gps->enable(timeStep);
  Motor *leftWheel = robot->getMotor("left wheel motor");
  Motor *rightWheel = robot->getMotor("right wheel motor");
  leftWheel->setPosition(INFINITY);
  rightWheel->setPosition(INFINITY);

  robot->step(timeStep); // Step once, so that the GPS has a value
  double startX = gps->getValues()[0], startZ = gps->getValues()[2];

  leftWheel->setVelocity(3.0);
  rightWheel->setVelocity(3.0);

  while (robot->step(timeStep) != -1) {
    double x = gps->getValues()[0], z = gps->getValues()[2];
    double distance = sqrt(pow(x - startX, 2) + pow(z - startZ, 2));
    cout << "Distance from the start: " << distance << " m" << endl;
    if (distance > 0.06) { // Half a tile
      leftWheel->setVelocity(0);
      rightWheel->setVelocity(0);
      break;
    }
  }

  delete robot;
  return 0;
}