121 lines
3.2 KiB
Python
121 lines
3.2 KiB
Python
import time
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import math
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import board
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import adafruit_hcsr04
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import pwmio
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import digitalio
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import rotaryio
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from adafruit_motor import motor
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# Mathematics
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diameter = 0.047 # 47mm wheel diameter
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circumference = diameter * math.pi
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target_dist = 5
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# Encoder constants
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GEAR_RATIO = 50 # The gear ratio of the motor
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COUNTS_PER_REV = 12 * GEAR_RATIO # The counts per revolution of the motor's output shaft
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ENCODER_NAMES = ["A", "D"]
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# Motor constants
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FREQUENCY = 25000
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DECAY_MODE = motor.SLOW_DECAY
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UPDATE_RATE = 100 # Hz
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SLEEP_TIME = 1 / UPDATE_RATE
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BASE_THROTTLE = 0.85 # Base throttle for both motors
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Kp_sync = 1.5 # Proportional gain for sync correction
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Kd_sync = 0.04
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prev_error = 0
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# Create a digitalinout object for the user switch
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user_sw = digitalio.DigitalInOut(board.USER_SW)
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user_sw.direction = digitalio.Direction.INPUT
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user_sw.pull = digitalio.Pull.UP
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# Set the pwm and motor pins
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pwm_a_p = pwmio.PWMOut(board.MOTOR_A_P, frequency=FREQUENCY)
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pwm_a_n = pwmio.PWMOut(board.MOTOR_A_N, frequency=FREQUENCY)
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pwm_d_p = pwmio.PWMOut(board.MOTOR_D_P, frequency=FREQUENCY)
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pwm_d_n = pwmio.PWMOut(board.MOTOR_D_N, frequency=FREQUENCY)
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mot_right = motor.DCMotor(pwm_a_p, pwm_a_n)
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mot_left = motor.DCMotor(pwm_d_p, pwm_d_n)
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mot_right.decay_mode = DECAY_MODE
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mot_left.decay_mode = DECAY_MODE
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# Create the encoder objects
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enc_right = rotaryio.IncrementalEncoder(board.ENCODER_A_B, board.ENCODER_A_A, divisor=1)
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enc_left = rotaryio.IncrementalEncoder(board.ENCODER_D_B, board.ENCODER_D_A, divisor=1)
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enc_right.position = 0
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enc_left.position = 0
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lastrevleft = 0
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lastrevright = 0
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revleft = 0
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revright = 0
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# Set the sensor pins
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sonar = adafruit_hcsr04.HCSR04(trigger_pin=board.TRIG, echo_pin=board.ECHO)
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def to_revs(position):
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return position / COUNTS_PER_REV
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def vel(rev, last_rev):
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return (rev - last_rev) / UPDATE_RATE
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while sonar.distance < 20:
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print("I am waiting...", sonar.distance)
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if sonar.distance >= 20:
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break
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print(">>>>> Starting movement!!!")
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while True:
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# Find the motor revolutions
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lastrevleft = revleft
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lastrevright = revright
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revleft = to_revs(enc_left.position)
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revright = to_revs(enc_right.position)
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vel_left = vel(revleft, lastrevleft)
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vel_right = vel(revright, lastrevright)
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# Encoder error due to friction.
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error = vel_left - vel_right
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derivative = (error - prev_error) / UPDATE_RATE
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prev_error = error
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correction = (Kp_sync * error) #+ (Kd_sync * derivative)
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left_throttle = BASE_THROTTLE - correction
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right_throttle = BASE_THROTTLE + correction
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left_throttle = max(min(left_throttle, 1.0), -1.0)
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right_throttle = max(min(right_throttle, 1.0), -1.0)
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distleft = revleft * circumference
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distright = revright * circumference
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avg = (abs(distleft) + abs(distright)) / 2
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print(f"Distance traveled: {avg:.3f} m")
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if avg >= target_dist:
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print("Target reached!!!")
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mot_left.throttle = 0
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mot_right.throttle = 0
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break
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mot_right.throttle = right_throttle
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mot_left.throttle = - left_throttle
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print(right_throttle, left_throttle)
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time.sleep(0.05)
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print("Finished!!!")
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