File content as of revision 9:085e090e1ec1:

/* University of York Robotics Laboratory PsiSwarm Library: Motor Functions Source File
 *
 * File: motors.cpp
 *
 * (C) Dept. Electronics & Computer Science, University of York
 * James Hilder, Alan Millard, Homero Elizondo, Jon Timmis
 *
 * PsiSwarm Library Version: 0.3
 *
 * October 2015
 *
 */

#include "psiswarm.h"

Timeout time_based_action_timeout;
char brake_when_done = 0;

void set_left_motor_speed(float speed)
{
    motor_left_speed = speed;
    motor_left_brake = 0;
    IF_update_motors();
}

void set_right_motor_speed(float speed)
{
    motor_right_speed = speed;
    motor_right_brake = 0;
    IF_update_motors();
}

void brake_left_motor()
{
    motor_left_speed = 0;
    motor_left_brake = 1;
    IF_update_motors();
}

void brake_right_motor()
{
    motor_right_speed = 0;
    motor_right_brake = 1;
    IF_update_motors();
}

void brake()
{
    motor_left_speed = 0;
    motor_right_speed = 0;
    motor_left_brake = 1;
    motor_right_brake = 1;
    IF_update_motors();
}

void stop()
{
    motor_left_speed = 0;
    motor_right_speed = 0;
    motor_left_brake = 0;
    motor_right_brake = 0;
    IF_update_motors();
}

void forward(float speed)
{
    motor_left_speed = speed;
    motor_right_speed = speed;
    motor_left_brake = 0;
    motor_right_brake = 0;
    IF_update_motors();
}

void backward(float speed)
{
    motor_left_speed = -speed;
    motor_right_speed = -speed;
    motor_left_brake = 0;
    motor_right_brake = 0;
    IF_update_motors();
}

void turn(float speed)
{
    //A positive turn is clockwise
    motor_left_speed = speed;
    motor_right_speed = -speed;
    motor_left_brake = 0;
    motor_right_brake = 0;
    IF_update_motors();
}

//Forward for a set period of time
void time_based_forward(float speed, int microseconds, char brake)
{
    //Check if a current time based action is running - if it is, throw a warning and cancel its timeout
    IF_check_time_for_existing_time_based_action();
        
    //Start moving
    forward(speed);
    brake_when_done = brake;
    time_based_action_timeout.attach_us(&IF_end_time_based_action,microseconds);
}

//Turn for a set period of time
void time_based_turn(float speed, int microseconds, char brake)
{
    //Check if a current time based action is running - if it is, throw a warning and cancel its timeout
    IF_check_time_for_existing_time_based_action();
        
    //Start turning
    turn(speed);
    brake_when_done = brake;
    time_based_action_timeout.attach_us(&IF_end_time_based_action,microseconds);
}

//Return the time in microseconds that performing the turn will take
int get_time_based_turn_time(float speed, float degrees)
{
    //Check sign of degrees
    if(degrees < 0) degrees =- degrees;
     
    //Main calculation for turn time
    float turn_time = degrees / ((290 * speed));

    //Add a hard offset of 4ms to account for start\stop time
    if(degrees > 4) {
       turn_time += 0.004;
    } else turn_time += 0.002;

    // Add offset for slow speed
    if(speed<0.31) {
        float mul_fact = 0.31 - speed;
        if(mul_fact < 0) mul_fact = 0;
        mul_fact /= 2;
        mul_fact += 1;
        turn_time *= mul_fact;
    }

    // Add offset for short turns
    if(degrees < 360) {
        float short_offset_multiplier = 1.0 + (0.9 / degrees);
        turn_time *= short_offset_multiplier;
    }
    
    // Convert to uS 
    turn_time *= 1000000;
    
    return (int) turn_time;   
}

//Turn the robot a set number of degrees [using time estimation to end turn]
int time_based_turn_degrees(float speed, float degrees, char brake)
{
    if(speed < 0 || speed > 1 || degrees == 0) {
        debug("Invalid values to time based turn: speed=%f degrees=$f\n",speed,degrees);
        return 0;
    } else {
        //Check if a current time based action is running - if it is, throw a warning and cancel its timeout
        IF_check_time_for_existing_time_based_action();
        
        //Calculate turn time using get_time_based_turn_time
        int turn_time = get_time_based_turn_time(speed,degrees);
        
        //Set correct turn direction (-degrees is a counter-clockwise turn)
       if(degrees < 0) {
            degrees=-degrees;
            speed=-speed;
        }

        //Start turning
        turn(speed);
        
        brake_when_done = brake;
        time_based_action_timeout.attach_us(&IF_end_time_based_action,turn_time);
        return turn_time;
    }
}

//Check if a current time based action is running - if it is, throw a warning and cancel its timeout
void IF_check_time_for_existing_time_based_action()
{
    if(time_based_motor_action == 1){
        time_based_action_timeout.detach(); 
        debug("WARNING: New time-based action called before previous action finished!\n");
    }   
    else time_based_motor_action = 1;
}

void IF_end_time_based_action()
{
    if(brake_when_done == 1)brake();
    else stop();
    time_based_motor_action = 0;
}

void IF_update_motors()
{
    if(motor_left_speed > 1.0) {
        motor_left_speed = 1.0;
        //Throw exception...
    }
    if(motor_right_speed > 1.0) {
        motor_right_speed = 1.0;
        //Throw exception...
    }
    if(motor_left_speed < -1.0) {
        motor_left_speed = -1.0;
        //Throw exception...
    }
    if(motor_right_speed < -1.0) {
        motor_right_speed = -1.0;
        //Throw exception...
    }
    if(motor_left_brake) {
        motor_left_f.write(1);
        motor_left_r.write(1);
        if(motor_left_speed!=0) {
            motor_left_speed = 0;
            //Throw exception...
        }
    } else {
        if(motor_left_speed >= 0) {
            motor_left_f.write(0);
            motor_left_r.write(IF_calibrated_speed(motor_left_speed));

        } else {
            motor_left_r.write(0);
            motor_left_f.write(IF_calibrated_speed(-motor_left_speed));
        }
    }
    if(motor_right_brake) {
        motor_right_f.write(1);
        motor_right_r.write(1);
        if(motor_right_speed!=0) {
            motor_right_speed = 0;
            //Throw exception...
        }
    } else {
        if(motor_right_speed >= 0) {
            motor_right_f.write(0);
            motor_right_r.write(IF_calibrated_speed(motor_right_speed));
        } else {
            motor_right_r.write(0);
            motor_right_f.write(IF_calibrated_speed(-motor_right_speed));
        }
    }

}


float IF_calibrated_speed(float speed)
{
    if(speed == 0) return 0;
    //Converts an input value to take account of the stall speed of the motor; aims to produce a more linear speed
    float adjusted = speed;
    if(OFFSET_MOTORS) {
        adjusted*=0.8f;
        adjusted+=0.2;
    }
    return adjusted;
}

void IF_init_motors()
{
    // Motor PWM outputs work optimally at 25kHz frequency
    motor_left_f.period_us(40);
    motor_right_f.period_us(40);
    motor_left_r.period_us(40);
    motor_right_r.period_us(40);
    motor_left_speed = 0;
    motor_right_speed = 0;
    motor_left_brake = 0;
    motor_right_brake = 0;
    IF_update_motors();
}