main_line_follower_base_ss24.cpp

#include "mbed.h"

// pes board pin map
#include "pm2_drivers/PESBoardPinMap.h"

// drivers
#include "pm2_drivers/DebounceIn.h"
#include "pm2_drivers/DCMotor.h"
#include "eigen/Dense.h"
#include "pm2_drivers/SensorBar.h"

#define M_PIf 3.14159265358979323846f /* pi */

bool do_execute_main_task = false; // this variable will be toggled via the user button (blue button) and
                                   // decides whether to execute the main task or not
bool do_reset_all_once = false;    // this variable is used to reset certain variables and objects and
                                   // shows how you can run a code segment only once

// objects for user button (blue button) handling on nucleo board
DebounceIn user_button(USER_BUTTON); // create DebounceIn object to evaluate the user button
                                     // falling and rising edge
void toggle_do_execute_main_fcn();   // custom function which is getting executed when user
                                     // button gets pressed, definition below

// main runs as an own thread
int main()
{
    // attach button fall function address to user button object, button has a pull-up resistor
    user_button.fall(&toggle_do_execute_main_fcn);

    // while loop gets executed every main_task_period_ms milliseconds, this is a
    // simple approach to repeatedly execute main
    const int main_task_period_ms = 20; // define main task period time in ms e.g. 20 ms, there for
                                        // the main task will run 50 times per second
    Timer main_task_timer;              // create Timer object which we use to run the main task
                                        // every main_task_period_ms

    // led on nucleo board
    DigitalOut user_led(USER_LED);

    // additional led
    // create DigitalOut object to command extra led, you need to add an aditional resistor, e.g. 220...500 Ohm
    // a led has an anode (+) and a cathode (-), the cathode needs to be connected to ground via a resistor
    DigitalOut led1(PB_9);

    // create object to enable power electronics for the dc motors
    DigitalOut enable_motors(PB_ENABLE_DCMOTORS);

    const float voltage_max = 12.0f; // maximum voltage of battery packs, adjust this to
                                     // 6.0f V if you only use one battery pack
    const float gear_ratio = 78.125f; 
    const float kn = 180.0f / 12.0f;
    // motor M1 and M2, do NOT enable motion planner, disabled per default
    DCMotor motor_M1(PB_PWM_M1, PB_ENC_A_M1, PB_ENC_B_M1, gear_ratio, kn, voltage_max);
    DCMotor motor_M2(PB_PWM_M2, PB_ENC_A_M2, PB_ENC_B_M2, gear_ratio, kn, voltage_max);

    const float r1_wheel = 0.0175f; // right wheel radius in meters
    const float r2_wheel = 0.0175f; // left  wheel radius in meters
    const float b_wheel = 0.1518f;  // wheelbase, distance from wheel to wheel in meters
    // transforms robot to wheel velocities
    Eigen::Matrix2f Cwheel2robot;
    Cwheel2robot << r1_wheel / 2.0f   ,  r2_wheel / 2.0f   ,
                    r1_wheel / b_wheel, -r2_wheel / b_wheel;

    const float bar_dist = 0.118f; // distance from wheel axis to leds on sensor bar / array in meters
    SensorBar sensorBar(PB_9, PB_8, bar_dist);

    // angle measured from sensor bar (black line) relative to robot
    float angle{0.0f};

    // rotational velocity controller
    const float Kp{5.0f};

    // velocity controller data
    const float wheel_vel_max = 2.0f * M_PIf * motor_M2.getMaxPhysicalVelocity();

    // start timer
    main_task_timer.start();

    // this loop will run forever
    while (true) {
        main_task_timer.reset();

        if (do_execute_main_task) {

            // visual feedback that the main task is executed, setting this once would actually be enough
            led1 = 1;
            enable_motors = 1;

            // only update sensor bar angle if a led is triggered
            if (sensorBar.isAnyLedActive()) {
                angle = sensorBar.getAvgAngleRad();
            }

            // control algorithm in robot velocities
            Eigen::Vector2f robot_coord = {0.5f * wheel_vel_max * r1_wheel, // half of the max. forward velocity
                                           Kp * angle};                     // proportional angle controller

            // map robot velocities to wheel velocities in rad/sec
            Eigen::Vector2f wheel_speed = Cwheel2robot.inverse() * robot_coord;

            // setpoints for the dc-motors in rps
            motor_M1.setVelocity(wheel_speed(0) / (2.0f * M_PIf)); // set a desired speed for speed controlled dc motors M1
            motor_M2.setVelocity(wheel_speed(1) / (2.0f * M_PIf)); // set a desired speed for speed controlled dc motors M2

        } else {
            // the following code block gets executed only once
            if (do_reset_all_once) {
                do_reset_all_once = false;

                // reset variables and objects
                led1 = 0;
                enable_motors = 0;
            }
        }

        // toggling the user led
        user_led = !user_led;

        // read timer and make the main thread sleep for the remaining time span (non blocking)
        int main_task_elapsed_time_ms = std::chrono::duration_cast<std::chrono::milliseconds>(main_task_timer.elapsed_time()).count();
        thread_sleep_for(main_task_period_ms - main_task_elapsed_time_ms);
    }
}

void toggle_do_execute_main_fcn()
{
    // toggle do_execute_main_task if the button was pressed
    do_execute_main_task = !do_execute_main_task;
    // set do_reset_all_once to true if do_execute_main_task changed from false to true
    if (do_execute_main_task)
        do_reset_all_once = true;
}