kopia lustrzana https://github.com/pimoroni/pimoroni-pico
97 wiersze
3.4 KiB
Python
97 wiersze
3.4 KiB
Python
import time
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from pimoroni import PID, NORMAL_DIR # , REVERSED_DIR
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from inventor import Inventor2040W, MOTOR_A
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"""
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A program to aid in the discovery and tuning of motor PID
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values for velocity control. It does this by commanding the
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motor to drive repeatedly between two setpoint speeds and
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plots the measured response.
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Press "User" to exit the program.
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"""
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GEAR_RATIO = 50 # The gear ratio of the motor
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DIRECTION = NORMAL_DIR # The direction to spin the motor in. NORMAL_DIR (0), REVERSED_DIR (1)
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SPEED_SCALE = 5.4 # The scaling to apply to the 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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PRINT_WINDOW = 0.25 # The time (in seconds) after a new setpoint, to display print out motor values
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MOVEMENT_WINDOW = 2.0 # The time (in seconds) between each new setpoint being set
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PRINT_DIVIDER = 1 # How many of the updates should be printed (i.e. 2 would be every other update)
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# Multipliers for the different printed values, so they appear nicely on the Thonny plotter
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ACC_PRINT_SCALE = 0.01 # Acceleration multiplier
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VELOCITY_EXTENT = 3 # How far from zero to drive the motor at, in revolutions per second
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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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# Create a new Inventor2040W and get a motor and encoder from it
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board = Inventor2040W(motor_gear_ratio=GEAR_RATIO)
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m = board.motors[MOTOR_A]
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enc = board.encoders[MOTOR_A]
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# Set the motor's speed scale
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m.speed_scale(SPEED_SCALE)
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# Set the motor and encoder's direction
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m.direction(DIRECTION)
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enc.direction(DIRECTION)
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# Create PID object for velocity control
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vel_pid = PID(VEL_KP, VEL_KI, VEL_KD, UPDATE_RATE)
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# Enable the motor to get started
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m.enable()
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# Set the initial setpoint velocity
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vel_pid.setpoint = VELOCITY_EXTENT
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update = 0
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print_count = 0
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# Continually move the motor until the user button is pressed
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while not board.switch_pressed():
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# Capture the state of the encoder
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capture = enc.capture()
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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_pid.calculate(capture.revolutions_per_second)
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# Accelerate or decelerate the motor
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m.speed(m.speed() + (accel * UPDATE_RATE))
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# Print out the current motor values and their setpoints,
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# but only for the first few updates and only every multiple
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if update < (PRINT_WINDOW * UPDATES) and print_count == 0:
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print("Vel =", capture.revolutions_per_second, end=", ")
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print("Vel SP =", vel_pid.setpoint, end=", ")
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print("Accel =", accel * ACC_PRINT_SCALE, end=", ")
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print("Speed =", m.speed())
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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 time window?
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if update >= (MOVEMENT_WINDOW * UPDATES):
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update = 0 # Reset the counter
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# Set the new velocity setpoint to be the inverse of the current setpoint
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vel_pid.setpoint = 0.0 - vel_pid.setpoint
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time.sleep(UPDATE_RATE)
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# Disable the motor
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m.disable()
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