pimoroni-pico/examples/motor2040/motor2040_quad_velocity_sequence.cpp

#include <cstdio>
#include "pico/stdlib.h"

#include "motor2040.hpp"
#include "button.hpp"
#include "pid.hpp"

/*
A demonstration of driving all four of Motor 2040's motor outputs through a
sequence of velocities, with the help of their attached encoders and PID control.

Press "Boot" to exit the program.
*/

using namespace motor;
using namespace encoder;

enum Wheels {
  FL = 2,
  FR = 3,
  RL = 1,
  RR = 0,
};

// The gear ratio of the motor
constexpr float GEAR_RATIO = 50.0f;

// The counts per revolution of the motor's output shaft
constexpr float COUNTS_PER_REV = MMME_CPR * GEAR_RATIO;

// The scaling to apply to the motor's speed to match its real-world speed
float SPEED_SCALE = 5.4f;

// How many times to update the motor per second
const uint UPDATES = 100;
constexpr float UPDATE_RATE = 1.0f / (float)UPDATES;

// The time to travel between each random value
constexpr float TIME_FOR_EACH_MOVE = 2.0f;
const uint UPDATES_PER_MOVE = TIME_FOR_EACH_MOVE * UPDATES;

// How many of the updates should be printed (i.e. 2 would be every other update)
const uint PRINT_DIVIDER = 4;

// The speed to drive the wheels at
constexpr float DRIVING_SPEED = 1.0f;

// PID values
constexpr float VEL_KP = 30.0f;   // Velocity proportional (P) gain
constexpr float VEL_KI = 0.0f;    // Velocity integral (I) gain
constexpr float VEL_KD = 0.4f;    // Velocity derivative (D) gain


// Create an array of motor pointers
const pin_pair motor_pins[] = {motor2040::MOTOR_A, motor2040::MOTOR_B,
                               motor2040::MOTOR_C, motor2040::MOTOR_D};
const uint NUM_MOTORS = count_of(motor_pins);
Motor *motors[NUM_MOTORS];

// Create an array of encoder pointers
const pin_pair encoder_pins[] = {motor2040::ENCODER_A, motor2040::ENCODER_B,
                                 motor2040::ENCODER_C, motor2040::ENCODER_D};
const char* ENCODER_NAMES[] = {"RR", "RL", "FL", "FR"};
const uint NUM_ENCODERS = count_of(encoder_pins);
Encoder *encoders[NUM_ENCODERS];

// Create the user button
Button user_sw(motor2040::USER_SW);

// Create an array of PID pointers
PID vel_pids[NUM_MOTORS];


// Helper functions for driving in common directions
void drive_forward(float speed) {
  vel_pids[FL].setpoint = speed;
  vel_pids[FR].setpoint = speed;
  vel_pids[RL].setpoint = speed;
  vel_pids[RR].setpoint = speed;
}

void turn_right(float speed) {
  vel_pids[FL].setpoint = speed;
  vel_pids[FR].setpoint = -speed;
  vel_pids[RL].setpoint = speed;
  vel_pids[RR].setpoint = -speed;
}

void strafe_right(float speed) {
  vel_pids[FL].setpoint = speed;
  vel_pids[FR].setpoint = -speed;
  vel_pids[RL].setpoint = -speed;
  vel_pids[RR].setpoint = speed;
}

void stop() {
  vel_pids[FL].setpoint = 0.0f;
  vel_pids[FR].setpoint = 0.0f;
  vel_pids[RL].setpoint = 0.0f;
  vel_pids[RR].setpoint = 0.0f;
}


int main() {
  stdio_init_all();

  // Fill the arrays of motors, encoders, and pids, and initialise them
  for(auto i = 0u; i < NUM_MOTORS; i++) {
    motors[i] = new Motor(motor_pins[i], NORMAL_DIR, SPEED_SCALE);
    motors[i]->init();

    encoders[i] = new Encoder(pio0, i, encoder_pins[i], PIN_UNUSED, NORMAL_DIR, COUNTS_PER_REV, true);
    encoders[i]->init();

    vel_pids[i] = PID(VEL_KP, VEL_KI, VEL_KD, UPDATE_RATE);
  }

  // Reverse the direction of the B and D motors and encoders
  motors[FL]->direction(REVERSED_DIR);
  motors[RL]->direction(REVERSED_DIR);
  encoders[FL]->direction(REVERSED_DIR);
  encoders[RL]->direction(REVERSED_DIR);

  // Enable all motors
  for(auto i = 0u; i < NUM_MOTORS; i++) {
    motors[i]->enable();
  }

  uint update = 0;
  uint print_count = 0;
  uint sequence = 0;

  Encoder::Capture captures[NUM_MOTORS];

  // Continually move the motor until the user button is pressed
  while(!user_sw.raw()) {

    // Capture the state of all the encoders
    for(auto i = 0u; i < NUM_MOTORS; i++) {
      captures[i] = encoders[i]->capture();
    }

    for(auto i = 0u; i < NUM_MOTORS; i++) {
      // Calculate the acceleration to apply to the motor to move it closer to the velocity setpoint
      float accel = vel_pids[i].calculate(captures[i].revolutions_per_second());

      // Accelerate or decelerate the motor
      motors[i]->speed(motors[i]->speed() + (accel * UPDATE_RATE));
    }

    // Print out the current motor values and their setpoints, but only on every multiple
    if(print_count == 0) {
      for(auto i = 0u; i < NUM_ENCODERS; i++) {
        printf("%s = %f, ", ENCODER_NAMES[i], captures[i].revolutions_per_second());
      }
      printf("\n");
    }

    // Increment the print count, and wrap it
    print_count = (print_count + 1) % PRINT_DIVIDER;

    update++;   // Move along in time

    // Have we reached the end of this movement?
    if(update >= UPDATES_PER_MOVE) {
        update = 0;  // Reset the counter

        // Move on to the next part of the sequence
        sequence += 1;

        // Loop the sequence back around
        if(sequence >= 7) {
          sequence = 0;
        }
    }

    // Set the motor speeds, based on the sequence
    switch(sequence) {
      case 0:
        drive_forward(DRIVING_SPEED);
        break;
      case 1:
        drive_forward(-DRIVING_SPEED);
        break;
      case 2:
        turn_right(DRIVING_SPEED);
        break;
      case 3:
        turn_right(-DRIVING_SPEED);
        break;
      case 4:
        strafe_right(DRIVING_SPEED);
        break;
      case 5:
        strafe_right(-DRIVING_SPEED);
        break;
      default:
        stop();
        break;
    }

    sleep_ms(UPDATE_RATE * 1000.0f);
  }

  // Stop all the motors
  for(auto m = 0u; m < NUM_MOTORS; m++) {
    motors[m]->disable();
  }
}