double get_bearing_in_degrees() {
const double *north = wb_compass_get_values(compass2);
double rad = atan2(north[0], north[2]);
double bearing = (rad - 1.5708) / M_PI * 180.0;
if (bearing < 0.0)
bearing = bearing + 360.0;
return bearing;
}
// Main function
int main(int argc, char **argv)
{
// Initialize webots
wb_robot_init();
// GPS tick data
int red_line_tick = 0;
int green_circle_tick = 0;
// Get robot devices
WbDeviceTag left_wheel = wb_robot_get_device("left_wheel");
WbDeviceTag right_wheel = wb_robot_get_device("right_wheel");
// Get robot sensors
WbDeviceTag forward_left_sensor = wb_robot_get_device("so3");
wb_distance_sensor_enable(forward_left_sensor, TIME_STEP);
WbDeviceTag forward_right_sensor = wb_robot_get_device("so4");
wb_distance_sensor_enable(forward_right_sensor, TIME_STEP);
WbDeviceTag left_sensor = wb_robot_get_device("so1");
wb_distance_sensor_enable(left_sensor, TIME_STEP);
// Get the compass
WbDeviceTag compass = wb_robot_get_device("compass");
wb_compass_enable(compass, TIME_STEP);
// Get the GPS data
WbDeviceTag gps = wb_robot_get_device("gps");
wb_gps_enable(gps, TIME_STEP);
// Prepare robot for velocity commands
wb_motor_set_position(left_wheel, INFINITY);
wb_motor_set_position(right_wheel, INFINITY);
wb_motor_set_velocity(left_wheel, 0.0);
wb_motor_set_velocity(right_wheel, 0.0);
// Begin in mode 0, moving forward
int mode = 0;
// Main loop
while (wb_robot_step(TIME_STEP) != -1) {
// Get the sensor data
double forward_left_value = wb_distance_sensor_get_value(forward_left_sensor);
double forward_right_value = wb_distance_sensor_get_value(forward_right_sensor);
double left_value = wb_distance_sensor_get_value(left_sensor);
// Read compass and convert to angle
const double *compass_val = wb_compass_get_values(compass);
double compass_angle = convert_bearing_to_degrees(compass_val);
// Read in the GPS data
const double *gps_val = wb_gps_get_values(gps);
// Debug
printf("Sensor input values:\n");
printf("- Forward left: %.2f.\n",forward_left_value);
printf("- Forward right: %.2f.\n",forward_right_value);
printf("- Right: %.2f.\n",left_value);
printf("- Compass angle (degrees): %.2f.\n", compass_angle);
printf("- GPS values (x,z): %.2f, %.2f.\n", gps_val[0], gps_val[2]);
// Send acuator commands
double left_speed, right_speed;
left_speed = 0;
right_speed = 0;
// List the current modes
printf("Mode: %d.\n", mode);
printf("Action: ");
/*
* There are four modes for this controller.
* They are listed as below:
* 0: Finding initial correct angle
* 1: Moving forward
* 2: Wall following
* 3: Rotating after correct point
* 4: Finding green circle + moving on
*/
// If it reaches GPS coords past the red line
if (gps_val[2] > 8.0) {
// Up the GPS tick
red_line_tick = red_line_tick + 1;
}
// If the red line tick tolerance reaches
// more than 10 per cycle, begin mode 3
if (red_line_tick > 10) {
mode = 3;
}
if (mode == 0) { // Mode 0: Find correct angle
printf("Finding correct angle\n");
if (compass_angle < (DESIRED_ANGLE - 1.0)) {
// Turn right
left_speed = MAX_SPEED;
right_speed = 0;
} else if (compass_angle > (DESIRED_ANGLE + 1.0)) {
// Turn left
left_speed = 0;
right_speed = MAX_SPEED;
} else {
// Reached the desired angle, move in a straight line
mode = 1;
}
} else if(mode == 1) { // Mode 1: Move forward
printf("Moving forward.\n");
left_speed = MAX_SPEED;
right_speed = MAX_SPEED;
// When sufficiently close to a wall in front of robot, switch mode to wall following
if ((forward_right_value > 500) || (forward_left_value > 500)) {
mode = 2;
}
}
else if (mode == 2) { // Mode 2: Wall following
if ((forward_right_value > 200) || (forward_left_value > 200)) {
printf("Backing up and turning right.\n");
left_speed = MAX_SPEED / 4.0;
right_speed = - MAX_SPEED / 2.0;
}
else {
if (left_value > 300) {
printf("Turning right away from wall.\n");
left_speed = MAX_SPEED;
right_speed = MAX_SPEED / 1.75;
}
else {
if (left_value < 200) {
printf("Turning left towards wall.\n");
left_speed = MAX_SPEED / 1.75;
right_speed = MAX_SPEED;
}
else {
printf("Moving forward along wall.\n");
left_speed = MAX_SPEED;
right_speed = MAX_SPEED;
}
}
}
} else if (mode == 3) {
// Once arrived, turn to the right
printf("Finding correct angle (again)\n");
if (compass_angle < (90 - 1.0)) {
// Turn right
left_speed = MAX_SPEED;
right_speed = MAX_SPEED / 1.75;
} else if (compass_angle > (90 + 1.0)) {
// Turn left
left_speed = MAX_SPEED / 1.75;
right_speed = MAX_SPEED;
} else {
// Reached the desired angle, move in a straight line
if (green_circle_tick > 10) {
left_speed = 0;
right_speed = 0;
} else {
left_speed = MAX_SPEED;
right_speed = MAX_SPEED;
}
if (gps_val[0] < -3.2) {
green_circle_tick = green_circle_tick + 1;
}
}
}
// Set the motor speeds.
wb_motor_set_velocity(left_wheel, left_speed);
wb_motor_set_velocity(right_wheel, right_speed);
// Perform simple simulation step
} while (wb_robot_step(TIME_STEP) != -1);
// Clean up webots
wb_robot_cleanup();
return 0;
}
