1,6 → 1,10 |
#!/usr/bin/python |
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# Python library for RPS01A MLAB module with AS5048B I2C Magnetic position sensor. |
# MLAB meteostation wind speed gauge with magnetic rotation sensor. |
# This simple algorithm calculate difference between five time equidistant points during the rotation. The result is angular speed per time step. |
# Size of time-step could be varied depending on expected wind speed range to measure. |
# Algorithm should be expanded by Kalman filtering to minimize dependence on fast reading. |
# The measuring principle could introduce time-stamped reading to increase precision of measurement. It could be possible because the readings are not exactly time equidistant in real Linux word. |
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#uncomment for debbug purposes |
#import logging |
9,6 → 13,7 |
import time |
import datetime |
import sys |
import numpy as np |
from pymlab import config |
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#### Script Arguments ############################################### |
64,24 → 69,39 |
#### Data Logging ################################################### |
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try: |
angles = np.zeros(5) |
angles[4] = sensor.get_angle(verify = False) |
time.sleep(0.01) |
angles[3] = sensor.get_angle(verify = False) |
time.sleep(0.01) |
angles[2] = sensor.get_angle(verify = False) |
time.sleep(0.01) |
angles[1] = sensor.get_angle(verify = False) |
n = 0 |
speed = 0 |
AVERAGING = 50 |
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while True: |
# for i in range(10): |
angle1 = sensor.get_angle(verify = False) |
time.sleep(0.1) |
angle2 = sensor.get_angle(verify = False) |
time.sleep(0.1) |
angle3 = sensor.get_angle(verify = False) |
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if (angle1 < angle2): |
speed = (angle2 - angle1)/0.01 |
else: |
speed = (360 - angle1 + angle2)/0.01 |
for i in range(AVERAGING): |
time.sleep(0.01) |
angles[0] = sensor.get_angle(verify = False) |
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sys.stdout.write("Speed: " + str(speed) +"\t"+ str(angle1) +"\t"+ str(angle2) + "\t\tMagnitude: " + str(sensor.get_magnitude()) |
+ "\tAGC Value: " + str(sensor.get_agc_value()) + "\tDiagnostics: " + str(sensor.get_diagnostics()) + "\r\n") |
sys.stdout.flush() |
time.sleep(0.01) |
if (angles[0] + n*360 - angles[1]) > 300: |
n -= 1 |
angles[0] = angles[0] + n*360 |
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elif (angles[0] + n*360 - angles[1]) < -300: # compute angular speed in backward direction. |
n += 1 |
angles[0] = angles[0] + n*360 |
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else: |
angles[0] = angles[0] + n*360 |
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speed += (-angles[4] + 8*angles[3] - 8*angles[1] + angles[0])/12 |
angles = np.roll(angles, 1) |
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speed = speed/AVERAGING # apply averaging on acummulated value. |
print "Speed: %0.2f \t Total Angle: %0.2f \r\n" % (speed, angles[0]) |
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except KeyboardInterrupt: |
sys.exit(0) |