forked from Archive/PX4-Autopilot
146 lines
4.7 KiB
Python
146 lines
4.7 KiB
Python
#!/usr/bin/env python
|
|
|
|
'''
|
|
fit best estimate of magnetometer offsets using the algorithm from
|
|
Bill Premerlani
|
|
'''
|
|
|
|
import sys, time, os, math
|
|
|
|
# allow import from the parent directory, where mavlink.py is
|
|
sys.path.insert(0, os.path.join(os.path.dirname(os.path.realpath(__file__)), '..'))
|
|
|
|
# command line option handling
|
|
from optparse import OptionParser
|
|
parser = OptionParser("magfit_delta.py [options]")
|
|
parser.add_option("--no-timestamps",dest="notimestamps", action='store_true', help="Log doesn't have timestamps")
|
|
parser.add_option("--condition",dest="condition", default=None, help="select packets by condition")
|
|
parser.add_option("--mav10", action='store_true', default=False, help="Use MAVLink protocol 1.0")
|
|
parser.add_option("--verbose", action='store_true', default=False, help="verbose offset output")
|
|
parser.add_option("--gain", type='float', default=0.01, help="algorithm gain")
|
|
parser.add_option("--noise", type='float', default=0, help="noise to add")
|
|
parser.add_option("--max-change", type='float', default=10, help="max step change")
|
|
parser.add_option("--min-diff", type='float', default=50, help="min mag vector delta")
|
|
parser.add_option("--history", type='int', default=20, help="how many points to keep")
|
|
parser.add_option("--repeat", type='int', default=1, help="number of repeats through the data")
|
|
|
|
(opts, args) = parser.parse_args()
|
|
|
|
if opts.mav10:
|
|
os.environ['MAVLINK10'] = '1'
|
|
import mavutil
|
|
from rotmat import Vector3, Matrix3
|
|
|
|
if len(args) < 1:
|
|
print("Usage: magfit_delta.py [options] <LOGFILE...>")
|
|
sys.exit(1)
|
|
|
|
def noise():
|
|
'''a noise vector'''
|
|
from random import gauss
|
|
v = Vector3(gauss(0, 1), gauss(0, 1), gauss(0, 1))
|
|
v.normalize()
|
|
return v * opts.noise
|
|
|
|
def find_offsets(data, ofs):
|
|
'''find mag offsets by applying Bills "offsets revisited" algorithm
|
|
on the data
|
|
|
|
This is an implementation of the algorithm from:
|
|
http://gentlenav.googlecode.com/files/MagnetometerOffsetNullingRevisited.pdf
|
|
'''
|
|
|
|
# a limit on the maximum change in each step
|
|
max_change = opts.max_change
|
|
|
|
# the gain factor for the algorithm
|
|
gain = opts.gain
|
|
|
|
data2 = []
|
|
for d in data:
|
|
d = d.copy() + noise()
|
|
d.x = float(int(d.x + 0.5))
|
|
d.y = float(int(d.y + 0.5))
|
|
d.z = float(int(d.z + 0.5))
|
|
data2.append(d)
|
|
data = data2
|
|
|
|
history_idx = 0
|
|
mag_history = data[0:opts.history]
|
|
|
|
for i in range(opts.history, len(data)):
|
|
B1 = mag_history[history_idx] + ofs
|
|
B2 = data[i] + ofs
|
|
|
|
diff = B2 - B1
|
|
diff_length = diff.length()
|
|
if diff_length <= opts.min_diff:
|
|
# the mag vector hasn't changed enough - we don't get any
|
|
# information from this
|
|
history_idx = (history_idx+1) % opts.history
|
|
continue
|
|
|
|
mag_history[history_idx] = data[i]
|
|
history_idx = (history_idx+1) % opts.history
|
|
|
|
# equation 6 of Bills paper
|
|
delta = diff * (gain * (B2.length() - B1.length()) / diff_length)
|
|
|
|
# limit the change from any one reading. This is to prevent
|
|
# single crazy readings from throwing off the offsets for a long
|
|
# time
|
|
delta_length = delta.length()
|
|
if max_change != 0 and delta_length > max_change:
|
|
delta *= max_change / delta_length
|
|
|
|
# set the new offsets
|
|
ofs = ofs - delta
|
|
|
|
if opts.verbose:
|
|
print ofs
|
|
return ofs
|
|
|
|
|
|
def magfit(logfile):
|
|
'''find best magnetometer offset fit to a log file'''
|
|
|
|
print("Processing log %s" % filename)
|
|
|
|
# open the log file
|
|
mlog = mavutil.mavlink_connection(filename, notimestamps=opts.notimestamps)
|
|
|
|
data = []
|
|
mag = None
|
|
offsets = Vector3(0,0,0)
|
|
|
|
# now gather all the data
|
|
while True:
|
|
# get the next MAVLink message in the log
|
|
m = mlog.recv_match(condition=opts.condition)
|
|
if m is None:
|
|
break
|
|
if m.get_type() == "SENSOR_OFFSETS":
|
|
# update offsets that were used during this flight
|
|
offsets = Vector3(m.mag_ofs_x, m.mag_ofs_y, m.mag_ofs_z)
|
|
if m.get_type() == "RAW_IMU" and offsets != None:
|
|
# extract one mag vector, removing the offsets that were
|
|
# used during that flight to get the raw sensor values
|
|
mag = Vector3(m.xmag, m.ymag, m.zmag) - offsets
|
|
data.append(mag)
|
|
|
|
print("Extracted %u data points" % len(data))
|
|
print("Current offsets: %s" % offsets)
|
|
|
|
# run the fitting algorithm
|
|
ofs = offsets
|
|
ofs = Vector3(0,0,0)
|
|
for r in range(opts.repeat):
|
|
ofs = find_offsets(data, ofs)
|
|
print('Loop %u offsets %s' % (r, ofs))
|
|
sys.stdout.flush()
|
|
print("New offsets: %s" % ofs)
|
|
|
|
total = 0.0
|
|
for filename in args:
|
|
magfit(filename)
|