161 lines
4.9 KiB
Python
161 lines
4.9 KiB
Python
import gc
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import time
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from motor import Motor, motor2040
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from encoder import Encoder, MMME_CPR
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from pimoroni import Button, PID, REVERSED_DIR
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"""
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A demonstration of driving all four of Motor 2040's motor outputs through a
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sequence of velocities, with the help of their attached encoders and PID control.
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Press "Boot" to exit the program.
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"""
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# Wheel friendly names
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FL = 2
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FR = 3
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RL = 1
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RR = 0
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GEAR_RATIO = 50 # The gear ratio of the motors
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COUNTS_PER_REV = MMME_CPR * GEAR_RATIO # The counts per revolution of each motor's output shaft
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SPEED_SCALE = 5.4 # The scaling to apply to each motor's speed to match its real-world speed
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UPDATES = 100 # How many times to update the motor per second
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UPDATE_RATE = 1 / UPDATES
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TIME_FOR_EACH_MOVE = 2 # The time to travel between each value
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UPDATES_PER_MOVE = TIME_FOR_EACH_MOVE * UPDATES
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PRINT_DIVIDER = 4 # How many of the updates should be printed (i.e. 2 would be every other update)
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DRIVING_SPEED = 1.0 # The speed to drive the wheels at
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# PID values
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VEL_KP = 30.0 # Velocity proportional (P) gain
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VEL_KI = 0.0 # Velocity integral (I) gain
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VEL_KD = 0.4 # Velocity derivative (D) gain
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# Free up hardware resources ahead of creating a new Encoder
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gc.collect()
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# Create a list of motors with a given speed scale
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MOTOR_PINS = [motor2040.MOTOR_A, motor2040.MOTOR_B, motor2040.MOTOR_C, motor2040.MOTOR_D]
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motors = [Motor(pins, speed_scale=SPEED_SCALE) for pins in MOTOR_PINS]
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# Create a list of encoders, using PIO 0, with the given counts per revolution
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ENCODER_PINS = [motor2040.ENCODER_A, motor2040.ENCODER_B, motor2040.ENCODER_C, motor2040.ENCODER_D]
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ENCODER_NAMES = ["RR", "RL", "FL", "FR"]
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encoders = [Encoder(0, i, ENCODER_PINS[i], counts_per_rev=COUNTS_PER_REV, count_microsteps=True) for i in range(motor2040.NUM_MOTORS)]
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# Reverse the direction of the B and D motors and encoders
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motors[FL].direction(REVERSED_DIR)
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motors[RL].direction(REVERSED_DIR)
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encoders[FL].direction(REVERSED_DIR)
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encoders[RL].direction(REVERSED_DIR)
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# Create the user button
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user_sw = Button(motor2040.USER_SW)
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# Create PID objects for position control
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vel_pids = [PID(VEL_KP, VEL_KI, VEL_KD, UPDATE_RATE) for i in range(motor2040.NUM_MOTORS)]
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# Helper functions for driving in common directions
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def drive_forward(speed):
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vel_pids[FL].setpoint = speed
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vel_pids[FR].setpoint = speed
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vel_pids[RL].setpoint = speed
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vel_pids[RR].setpoint = speed
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def turn_right(speed):
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vel_pids[FL].setpoint = speed
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vel_pids[FR].setpoint = -speed
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vel_pids[RL].setpoint = speed
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vel_pids[RR].setpoint = -speed
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def strafe_right(speed):
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vel_pids[FL].setpoint = speed
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vel_pids[FR].setpoint = -speed
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vel_pids[RL].setpoint = -speed
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vel_pids[RR].setpoint = speed
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def stop():
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vel_pids[FL].setpoint = 0
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vel_pids[FR].setpoint = 0
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vel_pids[RL].setpoint = 0
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vel_pids[RR].setpoint = 0
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# Enable the motor to get started
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for m in motors:
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m.enable()
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update = 0
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print_count = 0
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sequence = 0
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captures = [None] * motor2040.NUM_MOTORS
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# Continually move the motor until the user button is pressed
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while user_sw.raw() is not True:
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# Capture the state of all the encoders
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for i in range(motor2040.NUM_MOTORS):
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captures[i] = encoders[i].capture()
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for i in range(motor2040.NUM_MOTORS):
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# Calculate the acceleration to apply to the motor to move it closer to the velocity setpoint
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accel = vel_pids[i].calculate(captures[i].revolutions_per_second)
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# Accelerate or decelerate the motor
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motors[i].speed(motors[i].speed() + (accel * UPDATE_RATE))
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# Print out the current motor values, but only on every multiple
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if print_count == 0:
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for i in range(motor2040.NUM_MOTORS):
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print(ENCODER_NAMES[i], "=", captures[i].revolutions_per_second, end=", ")
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print()
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# Increment the print count, and wrap it
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print_count = (print_count + 1) % PRINT_DIVIDER
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update += 1 # Move along in time
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# Have we reached the end of this movement?
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if update >= UPDATES_PER_MOVE:
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update = 0 # Reset the counter
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# Move on to the next part of the sequence
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sequence += 1
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# Loop the sequence back around
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if sequence >= 7:
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sequence = 0
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# Set the motor speeds, based on the sequence
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if sequence == 0:
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drive_forward(DRIVING_SPEED)
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elif sequence == 1:
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drive_forward(-DRIVING_SPEED)
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elif sequence == 2:
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turn_right(DRIVING_SPEED)
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elif sequence == 3:
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turn_right(-DRIVING_SPEED)
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elif sequence == 4:
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strafe_right(DRIVING_SPEED)
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elif sequence == 5:
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strafe_right(-DRIVING_SPEED)
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elif sequence == 6:
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stop()
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time.sleep(UPDATE_RATE)
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# Stop all the motors
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for m in motors:
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m.disable()
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