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calibrate_servos.py
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calibrate_servos.py
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from pupper.HardwareInterface import HardwareInterface
from pupper.Config import PWMParams, ServoParams
import numpy as np
import re
def get_motor_name(i, j):
motor_type = {0: "abduction", 1: "inner", 2: "outer"} # Top # Bottom
leg_pos = {0: "front-right", 1: "front-left", 2: "back-right", 3: "back-left"}
final_name = motor_type[i] + " " + leg_pos[j]
return final_name
def get_motor_setpoint(i, j):
data = np.array([[0, 0, 0, 0], [45, 45, 45, 45], [45, 45, 45, 45]])
return data[i, j]
def degrees_to_radians(input_array):
"""Converts degrees to radians.
Parameters
----------
input_array : Numpy array or float
Degrees
Returns
-------
Numpy array or float
Radians
"""
return input_array * np.pi / 180.0
def radians_to_degrees(input_array):
"""Converts degrees to radians.
Parameters
----------
input_array : Numpy array or float
Radians
Returns
-------
Numpy array or float
Degrees
"""
return input_array * 180.0 / np.pi
def step_until(hardware_interface, axis, leg, set_point):
"""Returns the angle offset needed to correct a given link by asking the user for input.
Returns
-------
Float
Angle offset needed to correct the link.
"""
found_position = False
set_names = ["horizontal", "horizontal", "vertical"]
offset = 0
while not found_position:
move_input = str(
input("Enter 'a' or 'b' to move the link until it is **" + set_names[axis] + "**. Enter 'd' when done. Input: "
)
)
if move_input == "a":
offset += 1.0
hardware_interface.set_actuator_position(
degrees_to_radians(set_point + offset),
axis,
leg,
)
elif move_input == "b":
offset -= 1.0
hardware_interface.set_actuator_position(
degrees_to_radians(set_point + offset),
axis,
leg,
)
elif move_input == "d":
found_position = True
print("Offset: ", offset)
return offset
def calibrate_angle_offset(hardware_interface):
"""Calibrate the angle offset for the twelve motors on the robot. Note that servo_params is modified in-place.
Parameters
----------
servo_params : ServoParams
Servo parameters. This variable is updated in-place.
pi_board : Pi
RaspberryPi object.
pwm_params : PWMParams
PWMParams object.
"""
# Found K value of (11.4)
print("The scaling constant for your servo represents how much you have to increase\nthe pwm pulse width (in microseconds) to rotate the servo output 1 degree.")
print("This value is currently set to: {:.3f}".format(degrees_to_radians(hardware_interface.servo_params.micros_per_rad)))
print("For newer CLS6336 and CLS6327 servos the value should be 11.333.")
ks = input("Press <Enter> to keep the current value, or enter a new value: ")
if ks != '':
k = float(ks)
hardware_interface.servo_params.micros_per_rad = k * 180 / np.pi
hardware_interface.servo_params.neutral_angle_degrees = np.zeros((3, 4))
for leg_index in range(4):
for axis in range(3):
# Loop until we're satisfied with the calibration
completed = False
while not completed:
motor_name = get_motor_name(axis, leg_index)
print("\n\nCalibrating the **" + motor_name + " motor **")
set_point = get_motor_setpoint(axis, leg_index)
# Zero out the neutral angle
hardware_interface.servo_params.neutral_angle_degrees[axis, leg_index] = 0
# Move servo to set_point angle
hardware_interface.set_actuator_position(
degrees_to_radians(set_point),
axis,
leg_index,
)
# Adjust the angle using keyboard input until it matches the reference angle
offset = step_until(
hardware_interface, axis, leg_index, set_point
)
print("Final offset: ", offset)
# The upper leg link has a different equation because we're calibrating to make it horizontal, not vertical
if axis == 1:
hardware_interface.servo_params.neutral_angle_degrees[axis, leg_index] = set_point - offset
else:
hardware_interface.servo_params.neutral_angle_degrees[axis, leg_index] = -(set_point + offset)
print("Calibrated neutral angle: ", hardware_interface.servo_params.neutral_angle_degrees[axis, leg_index])
# Send the servo command using the new beta value and check that it's ok
hardware_interface.set_actuator_position(
degrees_to_radians([0, 45, -45][axis]),
axis,
leg_index,
)
okay = ""
prompt = "The leg should be at exactly **" + ["horizontal", "45 degrees", "45 degrees"][axis] + "**. Are you satisfied? Enter 'yes' or 'no': "
while okay not in ["y", "n", "yes", "no"]:
okay = str(
input(prompt)
)
completed = okay == "y" or okay == "yes"
def overwrite_ServoCalibration_file(servo_params):
preamble = """# WARNING: This file is machine generated. Edit at your own risk.
import numpy as np
"""
# Format array object string for np.array
p1 = re.compile("([0-9]\.) ( *)") # pattern to replace the space that follows each number with a comma
partially_formatted_matrix = p1.sub(r"\1,\2", str(servo_params.neutral_angle_degrees))
p2 = re.compile("(\]\n)") # pattern to add a comma at the end of the first two lines
formatted_matrix_with_required_commas = p2.sub("],\n", partially_formatted_matrix)
# Overwrite pupper/ServoCalibration.py file with modified values
with open("pupper/ServoCalibration.py", "w") as f:
print(preamble, file = f)
print("MICROS_PER_RAD = {:.3f} * 180.0 / np.pi".format(degrees_to_radians(servo_params.micros_per_rad)), file = f)
print("NEUTRAL_ANGLE_DEGREES = np.array(", file = f)
print(formatted_matrix_with_required_commas, file = f)
print(")", file = f)
def main():
"""Main program
"""
hardware_interface = HardwareInterface()
calibrate_angle_offset(hardware_interface)
overwrite_ServoCalibration_file(hardware_interface.servo_params)
print("\n\n CALIBRATION COMPLETE!\n")
print("Calibrated neutral angles:")
print(hardware_interface.servo_params.neutral_angle_degrees)
main()