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#!/usr/bin/python |
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#!/usr/bin/python |
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# Python library for RPS01A MLAB module with AS5048B I2C Magnetic position sensor. |
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# MLAB meteostation wind speed gauge with magnetic rotation sensor. |
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# This simple algorithm calculate difference between five time equidistant points during the rotation. The result is angular speed per time step. |
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# Size of time-step could be varied depending on expected wind speed range to measure. |
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# Algorithm should be expanded by Kalman filtering to minimize dependence on fast reading. |
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# 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 |
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#uncomment for debbug purposes |
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#import logging |
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#import logging |
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#logging.basicConfig(level=logging.DEBUG) |
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#logging.basicConfig(level=logging.DEBUG) |
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import time |
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import time |
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import datetime |
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import datetime |
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import sys |
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import sys |
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import numpy as np |
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from pymlab import config |
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from pymlab import config |
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#### Script Arguments ############################################### |
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#### Script Arguments ############################################### |
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if len(sys.argv) != 2: |
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if len(sys.argv) != 2: |
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print sensor.get_zero_position() |
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print sensor.get_zero_position() |
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#### Data Logging ################################################### |
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#### Data Logging ################################################### |
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try: |
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try: |
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angles = np.zeros(5) |
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angles[4] = sensor.get_angle(verify = False) |
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time.sleep(0.01) |
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angles[3] = sensor.get_angle(verify = False) |
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time.sleep(0.01) |
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angles[2] = sensor.get_angle(verify = False) |
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time.sleep(0.01) |
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angles[1] = sensor.get_angle(verify = False) |
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n = 0 |
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speed = 0 |
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AVERAGING = 50 |
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while True: |
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while True: |
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# for i in range(10): |
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for i in range(AVERAGING): |
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time.sleep(0.01) |
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angle1 = sensor.get_angle(verify = False) |
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angles[0] = sensor.get_angle(verify = False) |
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time.sleep(0.1) |
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angle2 = sensor.get_angle(verify = False) |
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if (angles[0] + n*360 - angles[1]) > 300: |
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time.sleep(0.1) |
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n -= 1 |
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angle3 = sensor.get_angle(verify = False) |
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angles[0] = angles[0] + n*360 |
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elif (angles[0] + n*360 - angles[1]) < -300: # compute angular speed in backward direction. |
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if (angle1 < angle2): |
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n += 1 |
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speed = (angle2 - angle1)/0.01 |
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angles[0] = angles[0] + n*360 |
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else: |
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else: |
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speed = (360 - angle1 + angle2)/0.01 |
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angles[0] = angles[0] + n*360 |
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sys.stdout.write("Speed: " + str(speed) +"\t"+ str(angle1) +"\t"+ str(angle2) + "\t\tMagnitude: " + str(sensor.get_magnitude()) |
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+ "\tAGC Value: " + str(sensor.get_agc_value()) + "\tDiagnostics: " + str(sensor.get_diagnostics()) + "\r\n") |
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speed += (-angles[4] + 8*angles[3] - 8*angles[1] + angles[0])/12 |
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sys.stdout.flush() |
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angles = np.roll(angles, 1) |
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speed = speed/AVERAGING # apply averaging on acummulated value. |
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time.sleep(0.01) |
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print "Speed: %0.2f \t Total Angle: %0.2f \r\n" % (speed, angles[0]) |
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except KeyboardInterrupt: |
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except KeyboardInterrupt: |
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sys.exit(0) |
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sys.exit(0) |