{"id":5291,"date":"2022-09-07T13:54:58","date_gmt":"2022-09-07T17:54:58","guid":{"rendered":"https:\/\/courses.ideate.cmu.edu\/16-223\/f2022\/work\/?p=5291"},"modified":"2022-09-07T13:54:59","modified_gmt":"2022-09-07T17:54:59","slug":"servo-motion-with-pico-hw-saloni-gandhi","status":"publish","type":"post","link":"https:\/\/courses.ideate.cmu.edu\/16-223\/f2022\/work\/2022\/09\/07\/servo-motion-with-pico-hw-saloni-gandhi\/","title":{"rendered":"Servo Motion with Pico HW: Saloni Gandhi"},"content":{"rendered":"\n

Choreographic Intent:<\/strong><\/p>\n\n\n\n

I created a pattern of oscillation to the main line of the song “I will always love you” by Whitney Houston. My main intent was to recreate the beat of this song using the sound of the servo motions.<\/p>\n\n\n\n

Code:<\/strong><\/p>\n\n\n\n

print(“Starting servo_sweep script.”)<\/p>\n\n\n\n

import math, time
import board
import pwmio<\/p>\n\n\n\n

——————————————————————————–<\/h1>\n\n\n\n

class Servo():
def init<\/strong>(self, pin, pulse_rate=50):
self.pwm = pwmio.PWMOut(board.GP0, duty_cycle=0, frequency=pulse_rate)<\/p>\n\n\n

\n    # Save the initialization arguments within the object for later reference.\n    self.pin = pin\n    self.pulse_rate = pulse_rate\n\n    # Initialize the other state variables.\n    self.target = None    # target angle; None indicates the "OFF" state\n    self.debug = False    # flag to control print output\n\ndef write(self, angle):\n\n    # calculate the desired pulse width in units of seconds\n    if angle is None:\n        pulse_width = 0.0\n    else:\n        pulse_width  = 0.001 + angle * (0.001 \/ 180.0)\n\n    # calculate the duration in seconds of a single pulse cycle\n    cycle_period = 1.0 \/ self.pulse_rate\n\n    # calculate the desired ratio of pulse ON time to cycle duration\n    duty_cycle   = pulse_width \/ cycle_period\n\n    # convert the ratio into a 16-bit fixed point integer\n    duty_fixed   = int(2**16 * duty_cycle)\n\n    # limit the ratio range and apply to the hardware driver\n    self.pwm.duty_cycle = min(max(duty_fixed, 0), 65535)\n\n    # save the target value in the object attribute (i.e. variable)\n    self.target = angle\n\n    # if requested, print some diagnostics to the console\n    if self.debug:\n        print(f"Driving servo to angle {angle}")\n        print(f" Pulse width {pulse_width} seconds")\n        print(f" Duty cycle {duty_cycle}")\n        print(f" Command value {self.pwm.duty_cycle}\\n")\n<\/pre>\n\n\n
——————————————————————————–<\/h1>\n\n\n\n
def linear_move(servo, start, end, speed=60, update_rate=50):
# Calculate the number of seconds to wait between target updates to allow
# the motor to move.
# Units: seconds = 1.0 \/ (cycles\/second)
interval = 1.0 \/ update_rate<\/p>\n\n\n
\n# Compute the size of each step in degrees.\n# Units:  degrees = (degrees\/second) * second\nstep = speed * interval\n\n# Output the start angle once before beginning the loop.  This guarantees at\n# least one angle will be output even if the start and end are equal.\nangle = start\nservo.write(angle)\n\n# Loop once for each incremental angle change.\nwhile angle != end:\n    time.sleep(interval)            # pause for the sampling interval\n\n    # Update the target angle.  The positive and negative movement directions\n    # are treated separately.\n    if end &gt;= start:\n        angle += step;              # movement in the positive direction\n        if angle &gt; end:\n            angle = end             # end at an exact position\n    else:\n        angle -= step               # movement in the negative direction\n        if angle < end:\n            angle = end             # end at an exact position\n\n    servo.write(angle)              # update the hardware\n<\/pre>\n\n\n
——————————————————————————–<\/h1>\n\n\n\n
def ringing_move(servo, q_d, q=0.0, qd=0.0, k=4math.pi<\/em>math.pi, b=2.0,
update_rate=50, duration=2.0, debug=False):<\/p>\n\n\n
\ninterval = 1.0 \/ update_rate\n\nwhile duration &gt; 0.0:\n    # Calculate the acceleration.\n    #   qdd         acceleration in angles\/sec^2\n    #   k           spring constant relating the acceleration to the angular displacement\n    #   b           damping constant relating the acceleration to velocity\n    qdd = k * (q_d - q) - b * qd\n\n    # integrate one time step using forward Euler integration\n    q  += qd  * interval    # position changes in proportion to velocity\n    qd += qdd * interval    # velocity changes in proportion to acceleration\n\n    # update the servo command with the new angle\n    servo.write(q)\n\n    # print the output for plotting if requested\n    if debug:\n        print(q)\n\n\n    time.sleep(interval)\n\n    duration -= interval\n<\/pre>\n\n\n
——————————————————————————–<\/h1>\n\n\n\n
Create an object to represent a servo on the given hardware pin.<\/h1>\n\n\n\n
print(“Creating servo object.”)
servo = Servo(board.GP0)<\/p>\n\n\n\n
print(“Starting main script.”)
while True:
# initial pause
time.sleep(2.0)<\/p>\n\n\n
\nprint("Starting ringing motions.")\n#and\nringing_move(servo, 90.0, duration=1)\n#i\nringing_move(servo, 45.0, duration=1)\n#e\nringing_move(servo, 90.0, duration=1)\nprint("Starting linear motions.")\n#i\nlinear_move(servo, 0.0, 180.0, speed=45)\n\n#will\nringing_move(servo, 90.0, duration=1)\n#al\nringing_move(servo, 45.0, duration=1)\n#ways\nlinear_move(servo, 180.0, 0.0, speed=45)\n#love\nringing_move(servo, 90.0, duration=1)\n#you\nlinear_move(servo, 0.0, 180.0, speed=45)\n\n# final pause\ntime.sleep(2.0)\n<\/pre>","protected":false},"excerpt":{"rendered":"
Choreographic Intent: I created a pattern of oscillation to the main line of the song “I will always love you” by Whitney Houston. My main intent was to…<\/p>\n","protected":false},"author":56,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"_links":{"self":[{"href":"https:\/\/courses.ideate.cmu.edu\/16-223\/f2022\/work\/wp-json\/wp\/v2\/posts\/5291"}],"collection":[{"href":"https:\/\/courses.ideate.cmu.edu\/16-223\/f2022\/work\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/courses.ideate.cmu.edu\/16-223\/f2022\/work\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/courses.ideate.cmu.edu\/16-223\/f2022\/work\/wp-json\/wp\/v2\/users\/56"}],"replies":[{"embeddable":true,"href":"https:\/\/courses.ideate.cmu.edu\/16-223\/f2022\/work\/wp-json\/wp\/v2\/comments?post=5291"}],"version-history":[{"count":1,"href":"https:\/\/courses.ideate.cmu.edu\/16-223\/f2022\/work\/wp-json\/wp\/v2\/posts\/5291\/revisions"}],"predecessor-version":[{"id":5292,"href":"https:\/\/courses.ideate.cmu.edu\/16-223\/f2022\/work\/wp-json\/wp\/v2\/posts\/5291\/revisions\/5292"}],"wp:attachment":[{"href":"https:\/\/courses.ideate.cmu.edu\/16-223\/f2022\/work\/wp-json\/wp\/v2\/media?parent=5291"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/courses.ideate.cmu.edu\/16-223\/f2022\/work\/wp-json\/wp\/v2\/categories?post=5291"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/courses.ideate.cmu.edu\/16-223\/f2022\/work\/wp-json\/wp\/v2\/tags?post=5291"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}