Biorobotics 7 / BioroboticsMotorControl

PID motor controll for the biorobotics project.

Dependencies:   FastPWM QEI

Dependents:   PID_example Motor_calibration Demo_mode Demo_mode ... more

motor.cpp@4:5353c5d0d2ed, 2018-10-31 (annotated)

Committer:
brass_phoenix
Date:
Wed Oct 31 06:13:15 2018 +0000
Revision:
4:5353c5d0d2ed
Parent:
2:b30a467e90d3
Child:
5:5537072b0e2e
+ Added stop function.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
brass_phoenix 0:009e84d7af32 1 #include "motor.h"
brass_phoenix 0:009e84d7af32 2
brass_phoenix 2:b30a467e90d3 3 Motor::Motor(PinName pwm_pin, PinName dir_pin, PinName encoder_a, PinName encoder_b):
brass_phoenix 2:b30a467e90d3 4 pwm_out(pwm_pin),
brass_phoenix 2:b30a467e90d3 5 dir_out(dir_pin),
brass_phoenix 2:b30a467e90d3 6 encoder(encoder_a, encoder_b, NC, PULSES_PER_ROTATION, QEI::X4_ENCODING)
brass_phoenix 2:b30a467e90d3 7 {
brass_phoenix 2:b30a467e90d3 8 pid = PID();
brass_phoenix 2:b30a467e90d3 9
brass_phoenix 2:b30a467e90d3 10 target_angle = 0;
brass_phoenix 2:b30a467e90d3 11
brass_phoenix 2:b30a467e90d3 12 printcount = 0;
brass_phoenix 2:b30a467e90d3 13 pid_period = 0;
brass_phoenix 2:b30a467e90d3 14 serial_debugging = false;
brass_phoenix 2:b30a467e90d3 15
brass_phoenix 2:b30a467e90d3 16 // 60 microseconds PWM period, 16.7 kHz, defines all PWM pins (only needs to be done once)
brass_phoenix 2:b30a467e90d3 17 pwm_out.period_us(60.0);
brass_phoenix 2:b30a467e90d3 18 }
brass_phoenix 2:b30a467e90d3 19
brass_phoenix 0:009e84d7af32 20 Motor::Motor(PinName pwm_pin, PinName dir_pin, PinName encoder_a, PinName encoder_b, Serial* pc):
brass_phoenix 0:009e84d7af32 21 pwm_out(pwm_pin),
brass_phoenix 0:009e84d7af32 22 dir_out(dir_pin),
brass_phoenix 0:009e84d7af32 23 encoder(encoder_a, encoder_b, NC, PULSES_PER_ROTATION, QEI::X4_ENCODING)
brass_phoenix 0:009e84d7af32 24 {
brass_phoenix 0:009e84d7af32 25 pid = PID();
brass_phoenix 0:009e84d7af32 26
brass_phoenix 0:009e84d7af32 27 target_angle = 0;
brass_phoenix 0:009e84d7af32 28
brass_phoenix 0:009e84d7af32 29 printcount = 0;
brass_phoenix 0:009e84d7af32 30 pid_period = 0;
brass_phoenix 0:009e84d7af32 31 this->pc = pc;
brass_phoenix 2:b30a467e90d3 32 serial_debugging = true;
brass_phoenix 0:009e84d7af32 33
brass_phoenix 0:009e84d7af32 34 // 60 microseconds PWM period, 16.7 kHz, defines all PWM pins (only needs to be done once)
brass_phoenix 0:009e84d7af32 35 pwm_out.period_us(60.0);
brass_phoenix 0:009e84d7af32 36 }
brass_phoenix 0:009e84d7af32 37
brass_phoenix 0:009e84d7af32 38 void Motor::start(float period) {
brass_phoenix 0:009e84d7af32 39 pid_period = period;
brass_phoenix 0:009e84d7af32 40 pid.set_period(period);
brass_phoenix 4:5353c5d0d2ed 41 motor_ticker.attach(callback(this, &Motor::update), period);
brass_phoenix 4:5353c5d0d2ed 42 }
brass_phoenix 4:5353c5d0d2ed 43
brass_phoenix 4:5353c5d0d2ed 44 void Motor::stop() {
brass_phoenix 4:5353c5d0d2ed 45 motor_ticker.detach();
brass_phoenix 4:5353c5d0d2ed 46 target_angle = 0;
brass_phoenix 4:5353c5d0d2ed 47 // Stop the actual motor.
brass_phoenix 4:5353c5d0d2ed 48 pwm_out = 0.0;
brass_phoenix 4:5353c5d0d2ed 49 dir_out = 0;
brass_phoenix 4:5353c5d0d2ed 50
brass_phoenix 4:5353c5d0d2ed 51 pid.clear_state();
brass_phoenix 4:5353c5d0d2ed 52
brass_phoenix 4:5353c5d0d2ed 53 printcount = 0;
brass_phoenix 0:009e84d7af32 54 }
brass_phoenix 0:009e84d7af32 55
brass_phoenix 0:009e84d7af32 56 void Motor::set_pid_k_values(double k_p, double k_i, double k_d) {
brass_phoenix 0:009e84d7af32 57 pid.set_k_values(k_p, k_i, k_d);
brass_phoenix 0:009e84d7af32 58 }
brass_phoenix 0:009e84d7af32 59
brass_phoenix 0:009e84d7af32 60 void Motor::set_target_angle(double angle) {
brass_phoenix 0:009e84d7af32 61 target_angle = angle;
brass_phoenix 0:009e84d7af32 62 }
brass_phoenix 0:009e84d7af32 63
brass_phoenix 0:009e84d7af32 64 double Motor::get_current_angle() {
brass_phoenix 0:009e84d7af32 65 return encoder_pulses_to_radians(encoder.getPulses());
brass_phoenix 0:009e84d7af32 66 }
brass_phoenix 0:009e84d7af32 67
brass_phoenix 0:009e84d7af32 68 void Motor::update() {
brass_phoenix 0:009e84d7af32 69 int pulses = encoder.getPulses();
brass_phoenix 0:009e84d7af32 70 double current_angle = encoder_pulses_to_radians(pulses);
brass_phoenix 0:009e84d7af32 71
brass_phoenix 0:009e84d7af32 72 double error = current_angle - target_angle;
brass_phoenix 0:009e84d7af32 73 // PID controll.
brass_phoenix 0:009e84d7af32 74 double speed_rps = pid.update(error);
brass_phoenix 0:009e84d7af32 75
brass_phoenix 0:009e84d7af32 76 double speed_pwm = radians_per_second_to_pwm(speed_rps);
brass_phoenix 0:009e84d7af32 77
brass_phoenix 2:b30a467e90d3 78 if (serial_debugging) {
brass_phoenix 2:b30a467e90d3 79
brass_phoenix 2:b30a467e90d3 80 printcount++;
brass_phoenix 2:b30a467e90d3 81 if (printcount >= 0.1L/pid_period) {
brass_phoenix 2:b30a467e90d3 82 pc->printf("c_angle: %f, d_angle: %f, error: %f, rps: %f, speed: %f\n", current_angle, target_angle, error, speed_rps, speed_pwm);
brass_phoenix 2:b30a467e90d3 83 printcount = 0;
brass_phoenix 2:b30a467e90d3 84 }
brass_phoenix 0:009e84d7af32 85 }
brass_phoenix 0:009e84d7af32 86
brass_phoenix 0:009e84d7af32 87 update_motor_speed(speed_pwm);
brass_phoenix 0:009e84d7af32 88 }
brass_phoenix 0:009e84d7af32 89
brass_phoenix 0:009e84d7af32 90
brass_phoenix 0:009e84d7af32 91 void Motor::update_motor_speed(double speed) {
brass_phoenix 0:009e84d7af32 92 if (speed < 1.0 && speed > 0) {
brass_phoenix 0:009e84d7af32 93 // Speed is in the range [0, 1] but the motor only moves
brass_phoenix 0:009e84d7af32 94 // in the range [0.5, 1]. Rescale for this.
brass_phoenix 0:009e84d7af32 95 speed = (speed * (1-MOTOR_STALL_PWM)) + MOTOR_STALL_PWM;
brass_phoenix 0:009e84d7af32 96 }
brass_phoenix 0:009e84d7af32 97 if (speed > -1.0 && speed < 0) {
brass_phoenix 0:009e84d7af32 98 // Speed is in the range [-1, 0] but the motor only moves
brass_phoenix 0:009e84d7af32 99 // in the range [-1, -0.5]. Rescale for this.
brass_phoenix 0:009e84d7af32 100 speed = (speed * (1-MOTOR_STALL_PWM)) - MOTOR_STALL_PWM;
brass_phoenix 0:009e84d7af32 101 }
brass_phoenix 0:009e84d7af32 102
brass_phoenix 0:009e84d7af32 103 // either true or false, determines direction (0 or 1)
brass_phoenix 0:009e84d7af32 104 dir_out = speed > 0;
brass_phoenix 0:009e84d7af32 105 // pwm duty cycle can only be positive, floating point absolute value (if value is >0, the there still will be a positive value).
brass_phoenix 0:009e84d7af32 106 pwm_out = fabs(speed);
brass_phoenix 0:009e84d7af32 107 }
brass_phoenix 0:009e84d7af32 108
brass_phoenix 0:009e84d7af32 109 double Motor::encoder_pulses_to_radians(int pulses) {
brass_phoenix 0:009e84d7af32 110 return (pulses/float(PULSES_PER_ROTATION)) * 2.0f*PI;
brass_phoenix 0:009e84d7af32 111 }
brass_phoenix 0:009e84d7af32 112
brass_phoenix 0:009e84d7af32 113
brass_phoenix 0:009e84d7af32 114 // Converts radians/s values into PWM values for motor controll.
brass_phoenix 0:009e84d7af32 115 // Both positive and negative values.
brass_phoenix 0:009e84d7af32 116 double Motor::radians_per_second_to_pwm(double rps) {
brass_phoenix 0:009e84d7af32 117 // If the rad/s is below the anti-jitter treshold, it is simply 0.
brass_phoenix 0:009e84d7af32 118 if (rps > 0 && rps < MOTOR_THRESHOLD_RPS) {
brass_phoenix 0:009e84d7af32 119 rps = 0;
brass_phoenix 0:009e84d7af32 120 }
brass_phoenix 0:009e84d7af32 121 if (rps < 0 && rps > -MOTOR_THRESHOLD_RPS) {
brass_phoenix 0:009e84d7af32 122 rps = 0;
brass_phoenix 0:009e84d7af32 123 }
brass_phoenix 0:009e84d7af32 124
brass_phoenix 0:009e84d7af32 125
brass_phoenix 0:009e84d7af32 126 // With our specific motor, full PWM is equal to 1 round per second.
brass_phoenix 0:009e84d7af32 127 // Or 2PI radians per second.
brass_phoenix 0:009e84d7af32 128 double pwm_speed = rps / (2*PI);
brass_phoenix 0:009e84d7af32 129
brass_phoenix 0:009e84d7af32 130 // PWM speeds can only go between [-1, 1]
brass_phoenix 0:009e84d7af32 131 if (pwm_speed > 1) { pwm_speed = 1; }
brass_phoenix 0:009e84d7af32 132 if (pwm_speed < -1) { pwm_speed = -1; }
brass_phoenix 0:009e84d7af32 133 return pwm_speed;
brass_phoenix 0:009e84d7af32 134 }