117 lines
4.4 KiB
Python
117 lines
4.4 KiB
Python
import gc
|
|
import time
|
|
import math
|
|
import random
|
|
from motor import Motor, motor2040
|
|
from encoder import Encoder, MMME_CPR
|
|
from pimoroni import Button, PID, NORMAL_DIR # , REVERSED_DIR
|
|
|
|
"""
|
|
An example of how to drive a motor smoothly between random speeds,
|
|
with the help of it's attached encoder and PID control.
|
|
|
|
Press "Boot" to exit the program.
|
|
"""
|
|
|
|
MOTOR_PINS = motor2040.MOTOR_A # The pins of the motor being profiled
|
|
ENCODER_PINS = motor2040.ENCODER_A # The pins of the encoder attached to the profiled motor
|
|
GEAR_RATIO = 50 # The gear ratio of the motor
|
|
COUNTS_PER_REV = MMME_CPR * GEAR_RATIO # The counts per revolution of the motor's output shaft
|
|
|
|
DIRECTION = NORMAL_DIR # The direction to spin the motor in. NORMAL_DIR (0), REVERSED_DIR (1)
|
|
SPEED_SCALE = 5.4 # The scaling to apply to the motor's speed to match its real-world speed
|
|
|
|
UPDATES = 100 # How many times to update the motor per second
|
|
UPDATE_RATE = 1 / UPDATES
|
|
TIME_FOR_EACH_MOVE = 1 # The time to travel between each random value, in seconds
|
|
UPDATES_PER_MOVE = TIME_FOR_EACH_MOVE * UPDATES
|
|
PRINT_DIVIDER = 4 # How many of the updates should be printed (i.e. 2 would be every other update)
|
|
|
|
# Multipliers for the different printed values, so they appear nicely on the Thonny plotter
|
|
ACC_PRINT_SCALE = 0.05 # Acceleration multiplier
|
|
|
|
VELOCITY_EXTENT = 3 # How far from zero to drive the motor at, in revolutions per second
|
|
INTERP_MODE = 2 # The interpolating mode between setpoints. STEP (0), LINEAR (1), COSINE (2)
|
|
|
|
# PID values
|
|
VEL_KP = 30.0 # Velocity proportional (P) gain
|
|
VEL_KI = 0.0 # Velocity integral (I) gain
|
|
VEL_KD = 0.4 # Velocity derivative (D) gain
|
|
|
|
|
|
# Free up hardware resources ahead of creating a new Encoder
|
|
gc.collect()
|
|
|
|
# Create a motor and set its speed scale
|
|
m = Motor(MOTOR_PINS, direction=DIRECTION, speed_scale=SPEED_SCALE)
|
|
|
|
# Create an encoder, using PIO 0 and State Machine 0
|
|
enc = Encoder(0, 0, ENCODER_PINS, direction=DIRECTION, counts_per_rev=COUNTS_PER_REV, count_microsteps=True)
|
|
|
|
# Create the user button
|
|
user_sw = Button(motor2040.USER_SW)
|
|
|
|
# Create PID object for velocity control
|
|
vel_pid = PID(VEL_KP, VEL_KI, VEL_KD, UPDATE_RATE)
|
|
|
|
# Enable the motor to get started
|
|
m.enable()
|
|
|
|
|
|
update = 0
|
|
print_count = 0
|
|
|
|
# Set the initial value and create a random end value between the extents
|
|
start_value = 0.0
|
|
end_value = random.uniform(-VELOCITY_EXTENT, VELOCITY_EXTENT)
|
|
|
|
# Continually move the motor until the user button is pressed
|
|
while not user_sw.raw():
|
|
|
|
# Capture the state of the encoder
|
|
capture = enc.capture()
|
|
|
|
# Calculate how far along this movement to be
|
|
percent_along = min(update / UPDATES_PER_MOVE, 1.0)
|
|
|
|
if INTERP_MODE == 0:
|
|
# Move the motor instantly to the end value
|
|
vel_pid.setpoint = end_value
|
|
elif INTERP_MODE == 2:
|
|
# Move the motor between values using cosine
|
|
vel_pid.setpoint = (((-math.cos(percent_along * math.pi) + 1.0) / 2.0) * (end_value - start_value)) + start_value
|
|
else:
|
|
# Move the motor linearly between values
|
|
vel_pid.setpoint = (percent_along * (end_value - start_value)) + start_value
|
|
|
|
# Calculate the acceleration to apply to the motor to move it closer to the velocity setpoint
|
|
accel = vel_pid.calculate(capture.revolutions_per_second)
|
|
|
|
# Accelerate or decelerate the motor
|
|
m.speed(m.speed() + (accel * UPDATE_RATE))
|
|
|
|
# Print out the current motor values and their setpoints, but only on every multiple
|
|
if print_count == 0:
|
|
print("Vel =", capture.revolutions_per_second, end=", ")
|
|
print("Vel SP =", vel_pid.setpoint, end=", ")
|
|
print("Accel =", accel * ACC_PRINT_SCALE, end=", ")
|
|
print("Speed =", m.speed())
|
|
|
|
# Increment the print count, and wrap it
|
|
print_count = (print_count + 1) % PRINT_DIVIDER
|
|
|
|
update += 1 # Move along in time
|
|
|
|
# Have we reached the end of this movement?
|
|
if update >= UPDATES_PER_MOVE:
|
|
update = 0 # Reset the counter
|
|
|
|
# Set the start as the last end and create a new random end value
|
|
start_value = end_value
|
|
end_value = random.uniform(-VELOCITY_EXTENT, VELOCITY_EXTENT)
|
|
|
|
time.sleep(UPDATE_RATE)
|
|
|
|
# Disable the motor
|
|
m.disable()
|