forked from Archive/PX4-Autopilot
155 lines
4.5 KiB
Python
155 lines
4.5 KiB
Python
#!/usr/bin/env python
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'''
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useful extra functions for use by mavlink clients
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Copyright Andrew Tridgell 2011
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Released under GNU GPL version 3 or later
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'''
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from math import *
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def kmh(mps):
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'''convert m/s to Km/h'''
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return mps*3.6
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def altitude(press_abs, ground_press=955.0, ground_temp=30):
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'''calculate barometric altitude'''
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return log(ground_press/press_abs)*(ground_temp+273.15)*29271.267*0.001
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def mag_heading(RAW_IMU, ATTITUDE, declination=0, SENSOR_OFFSETS=None, ofs=None):
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'''calculate heading from raw magnetometer'''
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mag_x = RAW_IMU.xmag
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mag_y = RAW_IMU.ymag
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mag_z = RAW_IMU.zmag
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if SENSOR_OFFSETS is not None and ofs is not None:
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mag_x += ofs[0] - SENSOR_OFFSETS.mag_ofs_x
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mag_y += ofs[1] - SENSOR_OFFSETS.mag_ofs_y
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mag_z += ofs[2] - SENSOR_OFFSETS.mag_ofs_z
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headX = mag_x*cos(ATTITUDE.pitch) + mag_y*sin(ATTITUDE.roll)*sin(ATTITUDE.pitch) + mag_z*cos(ATTITUDE.roll)*sin(ATTITUDE.pitch)
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headY = mag_y*cos(ATTITUDE.roll) - mag_z*sin(ATTITUDE.roll)
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heading = degrees(atan2(-headY,headX)) + declination
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if heading < 0:
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heading += 360
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return heading
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def mag_field(RAW_IMU, SENSOR_OFFSETS=None, ofs=None):
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'''calculate magnetic field strength from raw magnetometer'''
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mag_x = RAW_IMU.xmag
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mag_y = RAW_IMU.ymag
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mag_z = RAW_IMU.zmag
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if SENSOR_OFFSETS is not None and ofs is not None:
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mag_x += ofs[0] - SENSOR_OFFSETS.mag_ofs_x
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mag_y += ofs[1] - SENSOR_OFFSETS.mag_ofs_y
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mag_z += ofs[2] - SENSOR_OFFSETS.mag_ofs_z
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return sqrt(mag_x**2 + mag_y**2 + mag_z**2)
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def angle_diff(angle1, angle2):
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'''show the difference between two angles in degrees'''
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ret = angle1 - angle2
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if ret > 180:
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ret -= 360;
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if ret < -180:
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ret += 360
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return ret
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lowpass_data = {}
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def lowpass(var, key, factor):
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'''a simple lowpass filter'''
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global lowpass_data
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if not key in lowpass_data:
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lowpass_data[key] = var
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else:
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lowpass_data[key] = factor*lowpass_data[key] + (1.0 - factor)*var
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return lowpass_data[key]
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last_delta = {}
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def delta(var, key):
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'''calculate slope'''
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global last_delta
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dv = 0
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if key in last_delta:
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dv = var - last_delta[key]
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last_delta[key] = var
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return dv
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def delta_angle(var, key):
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'''calculate slope of an angle'''
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global last_delta
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dv = 0
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if key in last_delta:
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dv = var - last_delta[key]
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last_delta[key] = var
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if dv > 180:
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dv -= 360
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if dv < -180:
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dv += 360
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return dv
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def roll_estimate(RAW_IMU,smooth=0.7):
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'''estimate roll from accelerometer'''
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rx = lowpass(RAW_IMU.xacc,'rx',smooth)
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ry = lowpass(RAW_IMU.yacc,'ry',smooth)
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rz = lowpass(RAW_IMU.zacc,'rz',smooth)
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return degrees(-asin(ry/sqrt(rx**2+ry**2+rz**2)))
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def pitch_estimate(RAW_IMU, smooth=0.7):
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'''estimate pitch from accelerometer'''
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rx = lowpass(RAW_IMU.xacc,'rx',smooth)
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ry = lowpass(RAW_IMU.yacc,'ry',smooth)
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rz = lowpass(RAW_IMU.zacc,'rz',smooth)
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return degrees(asin(rx/sqrt(rx**2+ry**2+rz**2)))
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def gravity(RAW_IMU, SENSOR_OFFSETS=None, ofs=None, smooth=0.7):
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'''estimate pitch from accelerometer'''
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rx = RAW_IMU.xacc
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ry = RAW_IMU.yacc
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rz = RAW_IMU.zacc+45
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if SENSOR_OFFSETS is not None and ofs is not None:
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rx += ofs[0] - SENSOR_OFFSETS.accel_cal_x
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ry += ofs[1] - SENSOR_OFFSETS.accel_cal_y
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rz += ofs[2] - SENSOR_OFFSETS.accel_cal_z
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return lowpass(sqrt(rx**2+ry**2+rz**2)*0.01,'_gravity',smooth)
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def pitch_sim(SIMSTATE, GPS_RAW):
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'''estimate pitch from SIMSTATE accels'''
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xacc = SIMSTATE.xacc - lowpass(delta(GPS_RAW.v,"v")*6.6, "v", 0.9)
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zacc = SIMSTATE.zacc
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zacc += SIMSTATE.ygyro * GPS_RAW.v;
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if xacc/zacc >= 1:
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return 0
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if xacc/zacc <= -1:
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return -0
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return degrees(-asin(xacc/zacc))
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def distance_two(GPS_RAW1, GPS_RAW2):
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'''distance between two points'''
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lat1 = radians(GPS_RAW1.lat)
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lat2 = radians(GPS_RAW2.lat)
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lon1 = radians(GPS_RAW1.lon)
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lon2 = radians(GPS_RAW2.lon)
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dLat = lat2 - lat1
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dLon = lon2 - lon1
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a = sin(0.5*dLat) * sin(0.5*dLat) + sin(0.5*dLon) * sin(0.5*dLon) * cos(lat1) * cos(lat2)
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c = 2.0 * atan2(sqrt(a), sqrt(1.0-a))
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return 6371 * 1000 * c
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first_fix = None
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def distance_home(GPS_RAW):
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'''distance from first fix point'''
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global first_fix
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if first_fix == None or first_fix.fix_type < 2:
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first_fix = GPS_RAW
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return 0
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return distance_two(GPS_RAW, first_fix)
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