Uses my implementation of the Complementary Filter

KC6050ServoC.py

#!/usr/bin/python

# KC6050Servos.py Reads MPU6050 and also drives 2 servos
# Initially written by Adafruit and developed by S&S Dec 2014
 
import smbus
import math
import time
from Adafruit_PWM_Servo_Driver import PWM

# Initialise the PWM device using the default address
pwm = PWM(0x40)
# Note if you'd like more debug output you can instead run:
#pwm = PWM(0x40, debug=True)

servoMin = 150  # Min pulse length out of 4096
servoMax = 600  # Max pulse length out of 4096

# Power management registers
power_mgmt_1 = 0x6b
power_mgmt_2 = 0x6c

# Chip temperature register
temp = 0x41
celsius = (temp/340.00) + 36.53
print "Temp = ", "%.2f" % celsius, " deg C"  # Just for fun! (Hope it's right!)
 
def read_byte(adr):
    return bus.read_byte_data(address, adr)
 
def read_word(adr):
    high = bus.read_byte_data(address, adr)
    low = bus.read_byte_data(address, adr+1)
    val = (high << 8) + low
    return val
 
def read_word_2c(adr):
    val = read_word(adr)
    if (val >= 0x8000):
        return -((65535 - val) + 1)
    else:
        return val
 
def dist(a,b):
    return math.sqrt((a*a)+(b*b))
 
def get_y_rotation(x,y,z):
    radians = math.atan2(x, dist(y,z))
    return -math.degrees(radians)
 
def get_x_rotation(x,y,z):
    radians = math.atan2(y, dist(x,z))
    return math.degrees(radians)
    
def setServoPulse(channel, pulse):
    pulseLength = 1000000                   # 1,000,000 us per second
    pulseLength /= 60                       # 60 Hz
    print "%d us per period" % pulseLength
    pulseLength /= 4096                     # 12 bits of resolution
    print "%d us per bit" % pulseLength
    pulse *= 1000
    pulse /= pulseLength
    pwm.setPWM(channel, 0, pulse)

xrot = 0.0
yrot = 0.0

def read_data():
    global xrot
    global yrot
    global xangvel
    global yangvel

    gyro_xout = read_word_2c(0x43)
    gyro_yout = read_word_2c(0x45)
    gyro_zout = read_word_2c(0x47)

    xangvel = gyro_xout / 131.0         # gyro angular velocity in degrees/second
    yangvel = gyro_yout / 131.0
    zangvel = gyro_zout / 131.0

    accel_xout = read_word_2c(0x3b)
    accel_yout = read_word_2c(0x3d)
    accel_zout = read_word_2c(0x3f)
 
    accel_xout_scaled = accel_xout / 16384.0   # accelerometer rotation rate deg/s
    accel_yout_scaled = accel_yout / 16384.0
    accel_zout_scaled = accel_zout / 16384.0

    xrot = get_x_rotation(accel_xout_scaled, accel_yout_scaled, accel_zout_scaled)
    yrot = get_y_rotation(accel_xout_scaled, accel_yout_scaled, accel_zout_scaled)

def filtered_angle(gyro_angvel, accel_angle):
                                   # My implementation of the Complementary Filter
    delta_t = 0.003     # Approximate no of seconds each loop of the program takes
    taw = 0.001             # time constant of accelerometer noise (estimate in s)
    alpha = taw/(taw + delta_t)
    filteredAngle = (alpha * gyro_angvel * delta_t) + ((1-alpha)*accel_angle)
    return filteredAngle

pwm.setPWMFreq(60)      # Set frequency to 60 Hz
 
bus = smbus.SMBus(1)               # or bus = smbus.SMBus(1) for Revision 2 RasPis
address = 0x68          # This is the address value read via the i2cdetect command
 
# Now wake the 6050 up as it starts in sleep mode
bus.write_byte_data(address, power_mgmt_1, 0)

# Map servo rotation to MPU6050 orientation
slope = (servoMax-servoMin)/180.0
middle = servoMin+(servoMax-servoMin)/2

pwm.setPWM(11, 0, middle)
pwm.setPWM(15, 0, middle)

while (True):
  read_data()
  pwm.setPWM(15, 0, middle+int(slope*filtered_angle(xangvel, xrot)))
  pwm.setPWM(11, 0, middle+int(slope*filtered_angle(yangvel, yrot)))