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mavextra.py
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mavextra.py
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#!/usr/bin/env python
'''
useful extra functions for use by mavlink clients
Copyright Andrew Tridgell 2011
Released under GNU GPL version 3 or later
'''
from __future__ import print_function
from __future__ import absolute_import
from builtins import object
from math import *
try:
# in case numpy isn't installed
from .quaternion import Quaternion
except:
pass
try:
# rotmat doesn't work on Python3.2 yet
from .rotmat import Vector3, Matrix3
except Exception:
pass
def kmh(mps):
'''convert m/s to Km/h'''
return mps*3.6
def altitude(SCALED_PRESSURE, ground_pressure=None, ground_temp=None):
'''calculate barometric altitude'''
from . import mavutil
self = mavutil.mavfile_global
if ground_pressure is None:
if self.param('GND_ABS_PRESS', None) is None:
return 0
ground_pressure = self.param('GND_ABS_PRESS', 1)
if ground_temp is None:
ground_temp = self.param('GND_TEMP', 0)
scaling = ground_pressure / (SCALED_PRESSURE.press_abs*100.0)
temp = ground_temp + 273.15
return log(scaling) * temp * 29271.267 * 0.001
def altitude2(SCALED_PRESSURE, ground_pressure=None, ground_temp=None):
'''calculate barometric altitude'''
from . import mavutil
self = mavutil.mavfile_global
if ground_pressure is None:
if self.param('GND_ABS_PRESS', None) is None:
return 0
ground_pressure = self.param('GND_ABS_PRESS', 1)
if ground_temp is None:
ground_temp = self.param('GND_TEMP', 0)
scaling = SCALED_PRESSURE.press_abs*100.0 / ground_pressure
temp = ground_temp + 273.15
return 153.8462 * temp * (1.0 - exp(0.190259 * log(scaling)))
def mag_heading(RAW_IMU, ATTITUDE, declination=None, SENSOR_OFFSETS=None, ofs=None):
'''calculate heading from raw magnetometer'''
if declination is None:
from . import mavutil
declination = degrees(mavutil.mavfile_global.param('COMPASS_DEC', 0))
mag_x = RAW_IMU.xmag
mag_y = RAW_IMU.ymag
mag_z = RAW_IMU.zmag
if SENSOR_OFFSETS is not None and ofs is not None:
mag_x += ofs[0] - SENSOR_OFFSETS.mag_ofs_x
mag_y += ofs[1] - SENSOR_OFFSETS.mag_ofs_y
mag_z += ofs[2] - SENSOR_OFFSETS.mag_ofs_z
# go via a DCM matrix to match the APM calculation
dcm_matrix = rotation(ATTITUDE)
cos_pitch_sq = 1.0-(dcm_matrix.c.x*dcm_matrix.c.x)
headY = mag_y * dcm_matrix.c.z - mag_z * dcm_matrix.c.y
headX = mag_x * cos_pitch_sq - dcm_matrix.c.x * (mag_y * dcm_matrix.c.y + mag_z * dcm_matrix.c.z)
heading = degrees(atan2(-headY,headX)) + declination
if heading < 0:
heading += 360
return heading
def gps_time_to_epoch(week, msec):
'''convert GPS week and TOW to a time in seconds since 1970'''
epoch = 86400*(10*365 + int((1980-1969)/4) + 1 + 6 - 2)
return epoch + 86400*7*week + msec*0.001 - 18
def mag_heading_motors(RAW_IMU, ATTITUDE, declination, SENSOR_OFFSETS, ofs, SERVO_OUTPUT_RAW, motor_ofs):
'''calculate heading from raw magnetometer'''
ofs = get_motor_offsets(SERVO_OUTPUT_RAW, ofs, motor_ofs)
if declination is None:
from . import mavutil
declination = degrees(mavutil.mavfile_global.param('COMPASS_DEC', 0))
mag_x = RAW_IMU.xmag
mag_y = RAW_IMU.ymag
mag_z = RAW_IMU.zmag
if SENSOR_OFFSETS is not None and ofs is not None:
mag_x += ofs[0] - SENSOR_OFFSETS.mag_ofs_x
mag_y += ofs[1] - SENSOR_OFFSETS.mag_ofs_y
mag_z += ofs[2] - SENSOR_OFFSETS.mag_ofs_z
headX = mag_x*cos(ATTITUDE.pitch) + mag_y*sin(ATTITUDE.roll)*sin(ATTITUDE.pitch) + mag_z*cos(ATTITUDE.roll)*sin(ATTITUDE.pitch)
headY = mag_y*cos(ATTITUDE.roll) - mag_z*sin(ATTITUDE.roll)
heading = degrees(atan2(-headY,headX)) + declination
if heading < 0:
heading += 360
return heading
def mag_field(RAW_IMU, SENSOR_OFFSETS=None, ofs=None):
'''calculate magnetic field strength from raw magnetometer'''
mag_x = RAW_IMU.xmag
mag_y = RAW_IMU.ymag
mag_z = RAW_IMU.zmag
if SENSOR_OFFSETS is not None and ofs is not None:
mag_x += ofs[0] - SENSOR_OFFSETS.mag_ofs_x
mag_y += ofs[1] - SENSOR_OFFSETS.mag_ofs_y
mag_z += ofs[2] - SENSOR_OFFSETS.mag_ofs_z
return sqrt(mag_x**2 + mag_y**2 + mag_z**2)
def mag_field_df(MAG, ofs=None):
'''calculate magnetic field strength from raw magnetometer (dataflash version)'''
mag = Vector3(MAG.MagX, MAG.MagY, MAG.MagZ)
offsets = Vector3(MAG.OfsX, MAG.OfsY, MAG.OfsZ)
if ofs is not None:
mag = (mag - offsets) + Vector3(ofs[0], ofs[1], ofs[2])
return mag.length()
def get_motor_offsets(SERVO_OUTPUT_RAW, ofs, motor_ofs):
'''calculate magnetic field strength from raw magnetometer'''
from . import mavutil
self = mavutil.mavfile_global
m = SERVO_OUTPUT_RAW
motor_pwm = m.servo1_raw + m.servo2_raw + m.servo3_raw + m.servo4_raw
motor_pwm *= 0.25
rc3_min = self.param('RC3_MIN', 1100)
rc3_max = self.param('RC3_MAX', 1900)
motor = (motor_pwm - rc3_min) / (rc3_max - rc3_min)
if motor > 1.0:
motor = 1.0
if motor < 0.0:
motor = 0.0
motor_offsets0 = motor_ofs[0] * motor
motor_offsets1 = motor_ofs[1] * motor
motor_offsets2 = motor_ofs[2] * motor
ofs = (ofs[0] + motor_offsets0, ofs[1] + motor_offsets1, ofs[2] + motor_offsets2)
return ofs
def mag_field_motors(RAW_IMU, SENSOR_OFFSETS, ofs, SERVO_OUTPUT_RAW, motor_ofs):
'''calculate magnetic field strength from raw magnetometer'''
mag_x = RAW_IMU.xmag
mag_y = RAW_IMU.ymag
mag_z = RAW_IMU.zmag
ofs = get_motor_offsets(SERVO_OUTPUT_RAW, ofs, motor_ofs)
if SENSOR_OFFSETS is not None and ofs is not None:
mag_x += ofs[0] - SENSOR_OFFSETS.mag_ofs_x
mag_y += ofs[1] - SENSOR_OFFSETS.mag_ofs_y
mag_z += ofs[2] - SENSOR_OFFSETS.mag_ofs_z
return sqrt(mag_x**2 + mag_y**2 + mag_z**2)
def angle_diff(angle1, angle2):
'''show the difference between two angles in degrees'''
ret = angle1 - angle2
if ret > 180:
ret -= 360;
if ret < -180:
ret += 360
return ret
average_data = {}
def average(var, key, N):
'''average over N points'''
global average_data
if not key in average_data:
average_data[key] = [var]*N
return var
average_data[key].pop(0)
average_data[key].append(var)
return sum(average_data[key])/N
derivative_data = {}
def second_derivative_5(var, key):
'''5 point 2nd derivative'''
global derivative_data
from . import mavutil
tnow = mavutil.mavfile_global.timestamp
if not key in derivative_data:
derivative_data[key] = (tnow, [var]*5)
return 0
(last_time, data) = derivative_data[key]
data.pop(0)
data.append(var)
derivative_data[key] = (tnow, data)
h = (tnow - last_time)
# N=5 2nd derivative from
# http://www.holoborodko.com/pavel/numerical-methods/numerical-derivative/smooth-low-noise-differentiators/
ret = ((data[4] + data[0]) - 2*data[2]) / (4*h**2)
return ret
def second_derivative_9(var, key):
'''9 point 2nd derivative'''
global derivative_data
from . import mavutil
tnow = mavutil.mavfile_global.timestamp
if not key in derivative_data:
derivative_data[key] = (tnow, [var]*9)
return 0
(last_time, data) = derivative_data[key]
data.pop(0)
data.append(var)
derivative_data[key] = (tnow, data)
h = (tnow - last_time)
# N=5 2nd derivative from
# http://www.holoborodko.com/pavel/numerical-methods/numerical-derivative/smooth-low-noise-differentiators/
f = data
ret = ((f[8] + f[0]) + 4*(f[7] + f[1]) + 4*(f[6]+f[2]) - 4*(f[5]+f[3]) - 10*f[4])/(64*h**2)
return ret
lowpass_data = {}
def lowpass(var, key, factor):
'''a simple lowpass filter'''
global lowpass_data
if not key in lowpass_data:
lowpass_data[key] = var
else:
lowpass_data[key] = factor*lowpass_data[key] + (1.0 - factor)*var
return lowpass_data[key]
last_diff = {}
def diff(var, key):
'''calculate differences between values'''
global last_diff
ret = 0
if not key in last_diff:
last_diff[key] = var
return 0
ret = var - last_diff[key]
last_diff[key] = var
return ret
last_delta = {}
def delta(var, key, tusec=None):
'''calculate slope'''
global last_delta
if tusec is not None:
tnow = tusec * 1.0e-6
else:
from . import mavutil
tnow = mavutil.mavfile_global.timestamp
ret = 0
if key in last_delta:
(last_v, last_t, last_ret) = last_delta[key]
if last_t == tnow:
return last_ret
if tnow == last_t:
ret = 0
else:
ret = (var - last_v) / (tnow - last_t)
last_delta[key] = (var, tnow, ret)
return ret
def delta_angle(var, key, tusec=None):
'''calculate slope of an angle'''
global last_delta
if tusec is not None:
tnow = tusec * 1.0e-6
else:
from . import mavutil
tnow = mavutil.mavfile_global.timestamp
dv = 0
ret = 0
if key in last_delta:
(last_v, last_t, last_ret) = last_delta[key]
if last_t == tnow:
return last_ret
if tnow == last_t:
ret = 0
else:
dv = var - last_v
if dv > 180:
dv -= 360
if dv < -180:
dv += 360
ret = dv / (tnow - last_t)
last_delta[key] = (var, tnow, ret)
return ret
def roll_estimate(RAW_IMU,GPS_RAW_INT=None,ATTITUDE=None,SENSOR_OFFSETS=None, ofs=None, mul=None,smooth=0.7):
'''estimate roll from accelerometer'''
rx = RAW_IMU.xacc * 9.81 / 1000.0
ry = RAW_IMU.yacc * 9.81 / 1000.0
rz = RAW_IMU.zacc * 9.81 / 1000.0
if ATTITUDE is not None and GPS_RAW_INT is not None:
ry -= ATTITUDE.yawspeed * GPS_RAW_INT.vel*0.01
rz += ATTITUDE.pitchspeed * GPS_RAW_INT.vel*0.01
if SENSOR_OFFSETS is not None and ofs is not None:
rx += SENSOR_OFFSETS.accel_cal_x
ry += SENSOR_OFFSETS.accel_cal_y
rz += SENSOR_OFFSETS.accel_cal_z
rx -= ofs[0]
ry -= ofs[1]
rz -= ofs[2]
if mul is not None:
rx *= mul[0]
ry *= mul[1]
rz *= mul[2]
return lowpass(degrees(-asin(ry/sqrt(rx**2+ry**2+rz**2))),'_roll',smooth)
def pitch_estimate(RAW_IMU, GPS_RAW_INT=None,ATTITUDE=None, SENSOR_OFFSETS=None, ofs=None, mul=None, smooth=0.7):
'''estimate pitch from accelerometer'''
rx = RAW_IMU.xacc * 9.81 / 1000.0
ry = RAW_IMU.yacc * 9.81 / 1000.0
rz = RAW_IMU.zacc * 9.81 / 1000.0
if ATTITUDE is not None and GPS_RAW_INT is not None:
ry -= ATTITUDE.yawspeed * GPS_RAW_INT.vel*0.01
rz += ATTITUDE.pitchspeed * GPS_RAW_INT.vel*0.01
if SENSOR_OFFSETS is not None and ofs is not None:
rx += SENSOR_OFFSETS.accel_cal_x
ry += SENSOR_OFFSETS.accel_cal_y
rz += SENSOR_OFFSETS.accel_cal_z
rx -= ofs[0]
ry -= ofs[1]
rz -= ofs[2]
if mul is not None:
rx *= mul[0]
ry *= mul[1]
rz *= mul[2]
return lowpass(degrees(asin(rx/sqrt(rx**2+ry**2+rz**2))),'_pitch',smooth)
def rotation(ATTITUDE):
'''return the current DCM rotation matrix'''
r = Matrix3()
r.from_euler(ATTITUDE.roll, ATTITUDE.pitch, ATTITUDE.yaw)
return r
def mag_rotation(RAW_IMU, inclination, declination):
'''return an attitude rotation matrix that is consistent with the current mag
vector'''
m_body = Vector3(RAW_IMU.xmag, RAW_IMU.ymag, RAW_IMU.zmag)
m_earth = Vector3(m_body.length(), 0, 0)
r = Matrix3()
r.from_euler(0, -radians(inclination), radians(declination))
m_earth = r * m_earth
r.from_two_vectors(m_earth, m_body)
return r
def mag_pitch(RAW_IMU, inclination, declination):
'''estimate pithc from mag'''
m = mag_rotation(RAW_IMU, inclination, declination)
(r, p, y) = m.to_euler()
return degrees(p)
def mag_roll(RAW_IMU, inclination, declination):
'''estimate roll from mag'''
m = mag_rotation(RAW_IMU, inclination, declination)
(r, p, y) = m.to_euler()
return degrees(r)
def gravity(RAW_IMU, SENSOR_OFFSETS=None, ofs=None, mul=None, smooth=0.7):
'''estimate pitch from accelerometer'''
if hasattr(RAW_IMU, 'xacc'):
rx = RAW_IMU.xacc * 9.81 / 1000.0
ry = RAW_IMU.yacc * 9.81 / 1000.0
rz = RAW_IMU.zacc * 9.81 / 1000.0
else:
rx = RAW_IMU.AccX
ry = RAW_IMU.AccY
rz = RAW_IMU.AccZ
if SENSOR_OFFSETS is not None and ofs is not None:
rx += SENSOR_OFFSETS.accel_cal_x
ry += SENSOR_OFFSETS.accel_cal_y
rz += SENSOR_OFFSETS.accel_cal_z
rx -= ofs[0]
ry -= ofs[1]
rz -= ofs[2]
if mul is not None:
rx *= mul[0]
ry *= mul[1]
rz *= mul[2]
return sqrt(rx**2+ry**2+rz**2)
def pitch_sim(SIMSTATE, GPS_RAW):
'''estimate pitch from SIMSTATE accels'''
xacc = SIMSTATE.xacc - lowpass(delta(GPS_RAW.v,"v")*6.6, "v", 0.9)
zacc = SIMSTATE.zacc
zacc += SIMSTATE.ygyro * GPS_RAW.v;
if xacc/zacc >= 1:
return 0
if xacc/zacc <= -1:
return -0
return degrees(-asin(xacc/zacc))
def distance_two(GPS_RAW1, GPS_RAW2, horizontal=True):
'''distance between two points'''
if hasattr(GPS_RAW1, 'Lat'):
lat1 = radians(GPS_RAW1.Lat)
lat2 = radians(GPS_RAW2.Lat)
lon1 = radians(GPS_RAW1.Lng)
lon2 = radians(GPS_RAW2.Lng)
alt1 = GPS_RAW1.Alt
alt2 = GPS_RAW2.Alt
elif hasattr(GPS_RAW1, 'cog'):
lat1 = radians(GPS_RAW1.lat)*1.0e-7
lat2 = radians(GPS_RAW2.lat)*1.0e-7
lon1 = radians(GPS_RAW1.lon)*1.0e-7
lon2 = radians(GPS_RAW2.lon)*1.0e-7
alt1 = GPS_RAW1.alt*0.001
alt2 = GPS_RAW2.alt*0.001
else:
lat1 = radians(GPS_RAW1.lat)
lat2 = radians(GPS_RAW2.lat)
lon1 = radians(GPS_RAW1.lon)
lon2 = radians(GPS_RAW2.lon)
alt1 = GPS_RAW1.alt*0.001
alt2 = GPS_RAW2.alt*0.001
dLat = lat2 - lat1
dLon = lon2 - lon1
a = sin(0.5*dLat)**2 + sin(0.5*dLon)**2 * cos(lat1) * cos(lat2)
c = 2.0 * atan2(sqrt(a), sqrt(1.0-a))
ground_dist = 6371 * 1000 * c
if horizontal:
return ground_dist
return sqrt(ground_dist**2 + (alt2-alt1)**2)
first_fix = None
def distance_home(GPS_RAW):
'''distance from first fix point'''
global first_fix
if (hasattr(GPS_RAW, 'fix_type') and GPS_RAW.fix_type < 2) or \
(hasattr(GPS_RAW, 'Status') and GPS_RAW.Status < 2):
return 0
if first_fix is None:
first_fix = GPS_RAW
return 0
return distance_two(GPS_RAW, first_fix)
def sawtooth(ATTITUDE, amplitude=2.0, period=5.0):
'''sawtooth pattern based on uptime'''
mins = (ATTITUDE.usec * 1.0e-6)/60
p = fmod(mins, period*2)
if p < period:
return amplitude * (p/period)
return amplitude * (period - (p-period))/period
def rate_of_turn(speed, bank):
'''return expected rate of turn in degrees/s for given speed in m/s and
bank angle in degrees'''
if abs(speed) < 2 or abs(bank) > 80:
return 0
ret = degrees(9.81*tan(radians(bank))/speed)
return ret
def wingloading(bank):
'''return expected wing loading factor for a bank angle in radians'''
return 1.0/cos(bank)
def airspeed(VFR_HUD, ratio=None, used_ratio=None, offset=None):
'''recompute airspeed with a different ARSPD_RATIO'''
from . import mavutil
mav = mavutil.mavfile_global
if ratio is None:
ratio = 1.9936 # APM default
if used_ratio is None:
if 'ARSPD_RATIO' in mav.params:
used_ratio = mav.params['ARSPD_RATIO']
else:
print("no ARSPD_RATIO in mav.params")
used_ratio = ratio
if hasattr(VFR_HUD,'airspeed'):
airspeed = VFR_HUD.airspeed
else:
airspeed = VFR_HUD.Airspeed
airspeed_pressure = (airspeed**2) / used_ratio
if offset is not None:
airspeed_pressure += offset
if airspeed_pressure < 0:
airspeed_pressure = 0
airspeed = sqrt(airspeed_pressure * ratio)
return airspeed
def EAS2TAS(ARSP,GPS,BARO,ground_temp=25):
'''EAS2TAS from ARSP.Temp'''
tempK = ground_temp + 273.15 - 0.0065 * GPS.Alt
return sqrt(1.225 / (BARO.Press / (287.26 * tempK)))
def airspeed_ratio(VFR_HUD):
'''recompute airspeed with a different ARSPD_RATIO'''
from . import mavutil
mav = mavutil.mavfile_global
airspeed_pressure = (VFR_HUD.airspeed**2) / ratio
airspeed = sqrt(airspeed_pressure * ratio)
return airspeed
def airspeed_voltage(VFR_HUD, ratio=None):
'''back-calculate the voltage the airspeed sensor must have seen'''
from . import mavutil
mav = mavutil.mavfile_global
if ratio is None:
ratio = 1.9936 # APM default
if 'ARSPD_RATIO' in mav.params:
used_ratio = mav.params['ARSPD_RATIO']
else:
used_ratio = ratio
if 'ARSPD_OFFSET' in mav.params:
offset = mav.params['ARSPD_OFFSET']
else:
return -1
airspeed_pressure = (pow(VFR_HUD.airspeed,2)) / used_ratio
raw = airspeed_pressure + offset
SCALING_OLD_CALIBRATION = 204.8
voltage = 5.0 * raw / 4096
return voltage
def earth_rates(ATTITUDE):
'''return angular velocities in earth frame'''
from math import sin, cos, tan, fabs
p = ATTITUDE.rollspeed
q = ATTITUDE.pitchspeed
r = ATTITUDE.yawspeed
phi = ATTITUDE.roll
theta = ATTITUDE.pitch
psi = ATTITUDE.yaw
phiDot = p + tan(theta)*(q*sin(phi) + r*cos(phi))
thetaDot = q*cos(phi) - r*sin(phi)
if fabs(cos(theta)) < 1.0e-20:
theta += 1.0e-10
psiDot = (q*sin(phi) + r*cos(phi))/cos(theta)
return (phiDot, thetaDot, psiDot)
def roll_rate(ATTITUDE):
'''return roll rate in earth frame'''
(phiDot, thetaDot, psiDot) = earth_rates(ATTITUDE)
return phiDot
def pitch_rate(ATTITUDE):
'''return pitch rate in earth frame'''
(phiDot, thetaDot, psiDot) = earth_rates(ATTITUDE)
return thetaDot
def yaw_rate(ATTITUDE):
'''return yaw rate in earth frame'''
(phiDot, thetaDot, psiDot) = earth_rates(ATTITUDE)
return psiDot
def gps_velocity(GLOBAL_POSITION_INT):
'''return GPS velocity vector'''
return Vector3(GLOBAL_POSITION_INT.vx, GLOBAL_POSITION_INT.vy, GLOBAL_POSITION_INT.vz) * 0.01
def gps_velocity_old(GPS_RAW_INT):
'''return GPS velocity vector'''
return Vector3(GPS_RAW_INT.vel*0.01*cos(radians(GPS_RAW_INT.cog*0.01)),
GPS_RAW_INT.vel*0.01*sin(radians(GPS_RAW_INT.cog*0.01)), 0)
def gps_velocity_body(GPS_RAW_INT, ATTITUDE):
'''return GPS velocity vector in body frame'''
r = rotation(ATTITUDE)
return r.transposed() * Vector3(GPS_RAW_INT.vel*0.01*cos(radians(GPS_RAW_INT.cog*0.01)),
GPS_RAW_INT.vel*0.01*sin(radians(GPS_RAW_INT.cog*0.01)),
-tan(ATTITUDE.pitch)*GPS_RAW_INT.vel*0.01)
def earth_accel(RAW_IMU,ATTITUDE):
'''return earth frame acceleration vector'''
r = rotation(ATTITUDE)
accel = Vector3(RAW_IMU.xacc, RAW_IMU.yacc, RAW_IMU.zacc) * 9.81 * 0.001
return r * accel
def earth_gyro(RAW_IMU,ATTITUDE):
'''return earth frame gyro vector'''
r = rotation(ATTITUDE)
accel = Vector3(degrees(RAW_IMU.xgyro), degrees(RAW_IMU.ygyro), degrees(RAW_IMU.zgyro)) * 0.001
return r * accel
def airspeed_energy_error(NAV_CONTROLLER_OUTPUT, VFR_HUD):
'''return airspeed energy error matching APM internals
This is positive when we are going too slow
'''
aspeed_cm = VFR_HUD.airspeed*100
target_airspeed = NAV_CONTROLLER_OUTPUT.aspd_error + aspeed_cm
airspeed_energy_error = ((target_airspeed*target_airspeed) - (aspeed_cm*aspeed_cm))*0.00005
return airspeed_energy_error
def energy_error(NAV_CONTROLLER_OUTPUT, VFR_HUD):
'''return energy error matching APM internals
This is positive when we are too low or going too slow
'''
aspeed_energy_error = airspeed_energy_error(NAV_CONTROLLER_OUTPUT, VFR_HUD)
alt_error = NAV_CONTROLLER_OUTPUT.alt_error*100
energy_error = aspeed_energy_error + alt_error*0.098
return energy_error
def rover_turn_circle(SERVO_OUTPUT_RAW):
'''return turning circle (diameter) in meters for steering_angle in degrees
'''
# this matches Toms slash
max_wheel_turn = 35
wheelbase = 0.335
wheeltrack = 0.296
steering_angle = max_wheel_turn * (SERVO_OUTPUT_RAW.servo1_raw - 1500) / 400.0
theta = radians(steering_angle)
return (wheeltrack/2) + (wheelbase/sin(theta))
def rover_yaw_rate(VFR_HUD, SERVO_OUTPUT_RAW):
'''return yaw rate in degrees/second given steering_angle and speed'''
max_wheel_turn=35
speed = VFR_HUD.groundspeed
# assume 1100 to 1900 PWM on steering
steering_angle = max_wheel_turn * (SERVO_OUTPUT_RAW.servo1_raw - 1500) / 400.0
if abs(steering_angle) < 1.0e-6 or abs(speed) < 1.0e-6:
return 0
d = rover_turn_circle(SERVO_OUTPUT_RAW)
c = pi * d
t = c / speed
rate = 360.0 / t
return rate
def rover_lat_accel(VFR_HUD, SERVO_OUTPUT_RAW):
'''return lateral acceleration in m/s/s'''
speed = VFR_HUD.groundspeed
yaw_rate = rover_yaw_rate(VFR_HUD, SERVO_OUTPUT_RAW)
accel = radians(yaw_rate) * speed
return accel
def demix1(servo1, servo2, gain=0.5):
'''de-mix a mixed servo output'''
s1 = servo1 - 1500
s2 = servo2 - 1500
out1 = (s1+s2)*gain
out2 = (s1-s2)*gain
return out1+1500
def demix2(servo1, servo2, gain=0.5):
'''de-mix a mixed servo output'''
s1 = servo1 - 1500
s2 = servo2 - 1500
out1 = (s1+s2)*gain
out2 = (s1-s2)*gain
return out2+1500
def mixer(servo1, servo2, mixtype=1, gain=0.5):
'''mix two servos'''
s1 = servo1 - 1500
s2 = servo2 - 1500
v1 = (s1-s2)*gain
v2 = (s1+s2)*gain
if mixtype == 2:
v2 = -v2
elif mixtype == 3:
v1 = -v1
elif mixtype == 4:
v1 = -v1
v2 = -v2
if v1 > 600:
v1 = 600
elif v1 < -600:
v1 = -600
if v2 > 600:
v2 = 600
elif v2 < -600:
v2 = -600
return (1500+v1,1500+v2)
def mix1(servo1, servo2, mixtype=1, gain=0.5):
'''de-mix a mixed servo output'''
(v1,v2) = mixer(servo1, servo2, mixtype=mixtype, gain=gain)
return v1
def mix2(servo1, servo2, mixtype=1, gain=0.5):
'''de-mix a mixed servo output'''
(v1,v2) = mixer(servo1, servo2, mixtype=mixtype, gain=gain)
return v2
def wrap_180(angle):
if angle > 180:
angle -= 360.0
if angle < -180:
angle += 360.0
return angle
def wrap_360(angle):
if angle > 360:
angle -= 360.0
if angle < 0:
angle += 360.0
return angle
class DCM_State(object):
'''DCM state object'''
def __init__(self, roll, pitch, yaw):
self.dcm = Matrix3()
self.dcm2 = Matrix3()
self.dcm.from_euler(radians(roll), radians(pitch), radians(yaw))
self.dcm2.from_euler(radians(roll), radians(pitch), radians(yaw))
self.mag = Vector3()
self.gyro = Vector3()
self.accel = Vector3()
self.gps = None
self.rate = 50.0
self.kp = 0.2
self.kp_yaw = 0.3
self.omega_P = Vector3()
self.omega_P_yaw = Vector3()
self.omega_I = Vector3() # (-0.00199045287445, -0.00653007719666, -0.00714212376624)
self.omega_I_sum = Vector3()
self.omega_I_sum_time = 0
self.omega = Vector3()
self.ra_sum = Vector3()
self.last_delta_angle = Vector3()
self.last_velocity = Vector3()
(self.roll, self.pitch, self.yaw) = self.dcm.to_euler()
(self.roll2, self.pitch2, self.yaw2) = self.dcm2.to_euler()
def update(self, gyro, accel, mag, GPS):
if self.gyro != gyro or self.accel != accel:
delta_angle = old_div((gyro+self.omega_I), self.rate)
self.dcm.rotate(delta_angle)
correction = self.last_delta_angle % delta_angle
#print (delta_angle - self.last_delta_angle) * 58.0
corrected_delta = delta_angle + 0.0833333 * correction
self.dcm2.rotate(corrected_delta)
self.last_delta_angle = delta_angle
self.dcm.normalize()
self.dcm2.normalize()
self.gyro = gyro
self.accel = accel
(self.roll, self.pitch, self.yaw) = self.dcm.to_euler()
(self.roll2, self.pitch2, self.yaw2) = self.dcm2.to_euler()
dcm_state = None
def DCM_update(IMU, ATT, MAG, GPS):
'''implement full DCM system'''
global dcm_state
if dcm_state is None:
dcm_state = DCM_State(ATT.Roll, ATT.Pitch, ATT.Yaw)
mag = Vector3(MAG.MagX, MAG.MagY, MAG.MagZ)
gyro = Vector3(IMU.GyrX, IMU.GyrY, IMU.GyrZ)
accel = Vector3(IMU.AccX, IMU.AccY, IMU.AccZ)
accel2 = Vector3(IMU.AccX, IMU.AccY, IMU.AccZ)
dcm_state.update(gyro, accel, mag, GPS)
return dcm_state
class PX4_State(object):
'''PX4 DCM state object'''
def __init__(self, roll, pitch, yaw, timestamp):
self.dcm = Matrix3()
self.dcm.from_euler(radians(roll), radians(pitch), radians(yaw))
self.gyro = Vector3()
self.accel = Vector3()
self.timestamp = timestamp
(self.roll, self.pitch, self.yaw) = self.dcm.to_euler()
def update(self, gyro, accel, timestamp):
if self.gyro != gyro or self.accel != accel:
delta_angle = gyro * (timestamp - self.timestamp)
self.timestamp = timestamp
self.dcm.rotate(delta_angle)
self.dcm.normalize()
self.gyro = gyro
self.accel = accel
(self.roll, self.pitch, self.yaw) = self.dcm.to_euler()
px4_state = None
def PX4_update(IMU, ATT):
'''implement full DCM using PX4 native SD log data'''
global px4_state
if px4_state is None:
px4_state = PX4_State(degrees(ATT.Roll), degrees(ATT.Pitch), degrees(ATT.Yaw), IMU._timestamp)
gyro = Vector3(IMU.GyroX, IMU.GyroY, IMU.GyroZ)
accel = Vector3(IMU.AccX, IMU.AccY, IMU.AccZ)
px4_state.update(gyro, accel, IMU._timestamp)
return px4_state
_downsample_N = 0
def downsample(N):
'''conditional that is true on every Nth sample'''
global _downsample_N
_downsample_N = (_downsample_N + 1) % N
return _downsample_N == 0
def armed(HEARTBEAT):
'''return 1 if armed, 0 if not'''
from . import mavutil
if HEARTBEAT.type == mavutil.mavlink.MAV_TYPE_GCS:
self = mavutil.mavfile_global
if self.motors_armed():
return 1
return 0
if HEARTBEAT.base_mode & mavutil.mavlink.MAV_MODE_FLAG_SAFETY_ARMED:
return 1
return 0
def rotation_df(ATT):
'''return the current DCM rotation matrix'''
r = Matrix3()
r.from_euler(radians(ATT.Roll), radians(ATT.Pitch), radians(ATT.Yaw))
return r
def rotation2(AHRS2):
'''return the current DCM rotation matrix'''
r = Matrix3()
r.from_euler(AHRS2.roll, AHRS2.pitch, AHRS2.yaw)
return r
def earth_accel2(RAW_IMU,ATTITUDE):
'''return earth frame acceleration vector from AHRS2'''
r = rotation2(ATTITUDE)
accel = Vector3(RAW_IMU.xacc, RAW_IMU.yacc, RAW_IMU.zacc) * 9.81 * 0.001
return r * accel
def earth_accel_df(IMU,ATT):
'''return earth frame acceleration vector from df log'''
r = rotation_df(ATT)
accel = Vector3(IMU.AccX, IMU.AccY, IMU.AccZ)
return r * accel
def earth_accel2_df(IMU,IMU2,ATT):
'''return earth frame acceleration vector from df log'''
r = rotation_df(ATT)
accel1 = Vector3(IMU.AccX, IMU.AccY, IMU.AccZ)
accel2 = Vector3(IMU2.AccX, IMU2.AccY, IMU2.AccZ)
accel = 0.5 * (accel1 + accel2)
return r * accel
def gps_velocity_df(GPS):
'''return GPS velocity vector'''
vx = GPS.Spd * cos(radians(GPS.GCrs))
vy = GPS.Spd * sin(radians(GPS.GCrs))
return Vector3(vx, vy, GPS.VZ)
def distance_gps2(GPS, GPS2):
'''distance between two points'''
if GPS.TimeMS != GPS2.TimeMS:
# reject messages not time aligned
return None
return distance_two(GPS, GPS2)
radius_of_earth = 6378100.0 # in meters
def wrap_valid_longitude(lon):
''' wrap a longitude value around to always have a value in the range
[-180, +180) i.e 0 => 0, 1 => 1, -1 => -1, 181 => -179, -181 => 179
'''
return (((lon + 180.0) % 360.0) - 180.0)
def gps_newpos(lat, lon, bearing, distance):
'''extrapolate latitude/longitude given a heading and distance
thanks to http://www.movable-type.co.uk/scripts/latlong.html
'''
import math
lat1 = math.radians(lat)
lon1 = math.radians(lon)
brng = math.radians(bearing)
dr = distance/radius_of_earth
lat2 = math.asin(math.sin(lat1)*math.cos(dr) +
math.cos(lat1)*math.sin(dr)*math.cos(brng))
lon2 = lon1 + math.atan2(math.sin(brng)*math.sin(dr)*math.cos(lat1),
math.cos(dr)-math.sin(lat1)*math.sin(lat2))
return (math.degrees(lat2), wrap_valid_longitude(math.degrees(lon2)))
def gps_offset(lat, lon, east, north):
'''return new lat/lon after moving east/north
by the given number of meters'''
import math
bearing = math.degrees(math.atan2(east, north))
distance = math.sqrt(east**2 + north**2)
return gps_newpos(lat, lon, bearing, distance)
ekf_home = None
def ekf1_pos(EKF1):
'''calculate EKF position when EKF disabled'''
global ekf_home
from . import mavutil
self = mavutil.mavfile_global
if ekf_home is None:
if not 'GPS' in self.messages or self.messages['GPS'].Status != 3:
return None
ekf_home = self.messages['GPS']
(ekf_home.Lat, ekf_home.Lng) = gps_offset(ekf_home.Lat, ekf_home.Lng, -EKF1.PE, -EKF1.PN)
(lat,lon) = gps_offset(ekf_home.Lat, ekf_home.Lng, EKF1.PE, EKF1.PN)
return (lat, lon)
def quat_to_euler(q):
'''
Get Euler angles from a quaternion
:param q: quaternion [w, x, y , z]
:returns: euler angles [roll, pitch, yaw]
'''
quat = Quaternion(q)
return quat.euler
def euler_to_quat(e):
'''
Get quaternion from euler angles
:param e: euler angles [roll, pitch, yaw]
:returns: quaternion [w, x, y , z]
'''
quat = Quaternion(e)
return quat.q
def rotate_quat(attitude, roll, pitch, yaw):
'''
Returns rotated quaternion
:param attitude: quaternion [w, x, y , z]
:param roll: rotation in rad
:param pitch: rotation in rad
:param yaw: rotation in rad
:returns: quaternion [w, x, y , z]
'''
quat = Quaternion(attitude)
rotation = Quaternion([roll, pitch, yaw])
res = rotation * quat
return res.q
def qroll(MSG):
'''return quaternion roll in degrees'''
q = Quaternion([MSG.Q1,MSG.Q2,MSG.Q3,MSG.Q4])
return degrees(q.euler[0])
def qpitch(MSG):
'''return quaternion pitch in degrees'''
q = Quaternion([MSG.Q1,MSG.Q2,MSG.Q3,MSG.Q4])
return degrees(q.euler[1])
def qyaw(MSG):
'''return quaternion yaw in degrees'''
q = Quaternion([MSG.Q1,MSG.Q2,MSG.Q3,MSG.Q4])
return degrees(q.euler[2])
def euler_rotated(MSG, roll, pitch, yaw):
'''return eulers in radians from quaternion for view at given attitude in euler radians'''
rot_view = Matrix3()
rot_view.from_euler(roll, pitch, yaw)
q = Quaternion([MSG.Q1,MSG.Q2,MSG.Q3,MSG.Q4])
dcm = (rot_view * q.dcm.transposed()).transposed()
return dcm.to_euler()
def euler_p90(MSG):
'''return eulers in radians from quaternion for view at pitch 90'''
return euler_rotated(MSG, 0, radians(90), 0);
def qroll_p90(MSG):
'''return quaternion roll in degrees for view at pitch 90'''
return degrees(euler_p90(MSG)[0])
def qpitch_p90(MSG):
'''return quaternion roll in degrees for view at pitch 90'''
return degrees(euler_p90(MSG)[1])
def qyaw_p90(MSG):
'''return quaternion roll in degrees for view at pitch 90'''
return degrees(euler_p90(MSG)[2])
def rotation_df(ATT):
'''return the current DCM rotation matrix'''
r = Matrix3()