ardupilot/Tools/autotest/pysim/util.py

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import math
from math import sqrt, acos, cos, pi, sin, atan2
import os, sys, time, random
from rotmat import Vector3, Matrix3
from subprocess import call, check_call,Popen, PIPE
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def m2ft(x):
'''meters to feet'''
return float(x) / 0.3048
def ft2m(x):
'''feet to meters'''
return float(x) * 0.3048
def kt2mps(x):
return x * 0.514444444
def mps2kt(x):
return x / 0.514444444
def topdir():
'''return top of git tree where autotest is running from'''
d = os.path.dirname(os.path.realpath(__file__))
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assert(os.path.basename(d)=='pysim')
d = os.path.dirname(d)
assert(os.path.basename(d)=='autotest')
d = os.path.dirname(d)
assert(os.path.basename(d)=='Tools')
d = os.path.dirname(d)
return d
def reltopdir(path):
'''return a path relative to topdir()'''
return os.path.normpath(os.path.join(topdir(), path))
def run_cmd(cmd, dir=".", show=False, output=False, checkfail=True):
'''run a shell command'''
if show:
print("Running: '%s' in '%s'" % (cmd, dir))
if output:
return Popen([cmd], shell=True, stdout=PIPE, cwd=dir).communicate()[0]
elif checkfail:
return check_call(cmd, shell=True, cwd=dir)
else:
return call(cmd, shell=True, cwd=dir)
def rmfile(path):
'''remove a file if it exists'''
try:
os.unlink(path)
except Exception:
pass
def deltree(path):
'''delete a tree of files'''
run_cmd('rm -rf %s' % path)
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def build_SIL(atype, target='sitl', j=1):
'''build desktop SIL'''
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run_cmd("make clean",
dir=reltopdir(atype),
checkfail=True)
run_cmd("make -j%u %s" % (j, target),
dir=reltopdir(atype),
checkfail=True)
return True
# list of pexpect children to close on exit
close_list = []
def pexpect_autoclose(p):
'''mark for autoclosing'''
global close_list
close_list.append(p)
def pexpect_close(p):
'''close a pexpect child'''
global close_list
try:
p.close()
except Exception:
pass
try:
p.close(force=True)
except Exception:
pass
if p in close_list:
close_list.remove(p)
def pexpect_close_all():
'''close all pexpect children'''
global close_list
for p in close_list[:]:
pexpect_close(p)
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def pexpect_drain(p):
'''drain any pending input'''
import pexpect
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try:
p.read_nonblocking(1000, timeout=0)
except pexpect.TIMEOUT:
pass
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def start_SIL(atype, valgrind=False, wipe=False, synthetic_clock=True, home=None, model=None, speedup=1):
'''launch a SIL instance'''
import pexpect
cmd=""
if valgrind and os.path.exists('/usr/bin/valgrind'):
cmd += 'valgrind -q --log-file=%s-valgrind.log ' % atype
executable = reltopdir('tmp/%s.build/%s.elf' % (atype, atype))
if not os.path.exists(executable):
executable = '/tmp/%s.build/%s.elf' % (atype, atype)
cmd += executable
if wipe:
cmd += ' -w'
if synthetic_clock:
cmd += ' -S'
if home is not None:
cmd += ' --home=%s' % home
if model is not None:
cmd += ' --model=%s' % model
if speedup != 1:
cmd += ' --speedup=%f' % speedup
print("Running: %s" % cmd)
ret = pexpect.spawn(cmd, logfile=sys.stdout, timeout=5)
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ret.delaybeforesend = 0
pexpect_autoclose(ret)
ret.expect('Waiting for connection')
return ret
def start_MAVProxy_SIL(atype, aircraft=None, setup=False, master='tcp:127.0.0.1:5760',
options=None, logfile=sys.stdout):
'''launch mavproxy connected to a SIL instance'''
import pexpect
global close_list
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MAVPROXY = os.getenv('MAVPROXY_CMD', 'mavproxy.py')
cmd = MAVPROXY + ' --master=%s --out=127.0.0.1:14550' % master
if setup:
cmd += ' --setup'
if aircraft is None:
aircraft = 'test.%s' % atype
cmd += ' --aircraft=%s' % aircraft
if options is not None:
cmd += ' ' + options
ret = pexpect.spawn(cmd, logfile=logfile, timeout=60)
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ret.delaybeforesend = 0
pexpect_autoclose(ret)
return ret
def expect_setup_callback(e, callback):
'''setup a callback that is called once a second while waiting for
patterns'''
import pexpect
def _expect_callback(pattern, timeout=e.timeout):
tstart = time.time()
while time.time() < tstart + timeout:
try:
ret = e.expect_saved(pattern, timeout=1)
return ret
except pexpect.TIMEOUT:
e.expect_user_callback(e)
pass
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print("Timed out looking for %s" % pattern)
raise pexpect.TIMEOUT(timeout)
e.expect_user_callback = callback
e.expect_saved = e.expect
e.expect = _expect_callback
def mkdir_p(dir):
'''like mkdir -p'''
if not dir:
return
if dir.endswith("/"):
mkdir_p(dir[:-1])
return
if os.path.isdir(dir):
return
mkdir_p(os.path.dirname(dir))
os.mkdir(dir)
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def loadfile(fname):
'''load a file as a string'''
f = open(fname, mode='r')
r = f.read()
f.close()
return r
def lock_file(fname):
'''lock a file'''
import fcntl
f = open(fname, mode='w')
try:
fcntl.lockf(f, fcntl.LOCK_EX | fcntl.LOCK_NB)
except Exception:
return None
return f
def check_parent(parent_pid=None):
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'''check our parent process is still alive'''
if parent_pid is None:
try:
parent_pid = os.getppid()
except Exception:
pass
if parent_pid is None:
return
try:
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os.kill(parent_pid, 0)
except Exception:
print("Parent had finished - exiting")
sys.exit(1)
def EarthRatesToBodyRates(dcm, earth_rates):
'''convert the angular velocities from earth frame to
body frame. Thanks to James Goppert for the formula
all inputs and outputs are in radians
returns a gyro vector in body frame, in rad/s
'''
from math import sin, cos
(phi, theta, psi) = dcm.to_euler()
phiDot = earth_rates.x
thetaDot = earth_rates.y
psiDot = earth_rates.z
p = phiDot - psiDot*sin(theta)
q = cos(phi)*thetaDot + sin(phi)*psiDot*cos(theta)
r = cos(phi)*psiDot*cos(theta) - sin(phi)*thetaDot
return Vector3(p, q, r)
def BodyRatesToEarthRates(dcm, gyro):
'''convert the angular velocities from body frame to
earth frame.
all inputs and outputs are in radians/s
returns a earth rate vector
'''
from math import sin, cos, tan, fabs
p = gyro.x
q = gyro.y
r = gyro.z
(phi, theta, psi) = dcm.to_euler()
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 Vector3(phiDot, thetaDot, psiDot)
radius_of_earth = 6378100.0 # in meters
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
'''
from math import sin, asin, cos, atan2, radians, degrees
lat1 = radians(lat)
lon1 = radians(lon)
brng = radians(bearing)
dr = distance/radius_of_earth
lat2 = asin(sin(lat1)*cos(dr) +
cos(lat1)*sin(dr)*cos(brng))
lon2 = lon1 + atan2(sin(brng)*sin(dr)*cos(lat1),
cos(dr)-sin(lat1)*sin(lat2))
return (degrees(lat2), degrees(lon2))
def gps_distance(lat1, lon1, lat2, lon2):
'''return distance between two points in meters,
coordinates are in degrees
thanks to http://www.movable-type.co.uk/scripts/latlong.html'''
lat1 = math.radians(lat1)
lat2 = math.radians(lat2)
lon1 = math.radians(lon1)
lon2 = math.radians(lon2)
dLat = lat2 - lat1
dLon = lon2 - lon1
a = math.sin(0.5*dLat)**2 + math.sin(0.5*dLon)**2 * math.cos(lat1) * math.cos(lat2)
c = 2.0 * math.atan2(math.sqrt(a), math.sqrt(1.0-a))
return radius_of_earth * c
def gps_bearing(lat1, lon1, lat2, lon2):
'''return bearing between two points in degrees, in range 0-360
thanks to http://www.movable-type.co.uk/scripts/latlong.html'''
lat1 = math.radians(lat1)
lat2 = math.radians(lat2)
lon1 = math.radians(lon1)
lon2 = math.radians(lon2)
dLat = lat2 - lat1
dLon = lon2 - lon1
y = math.sin(dLon) * math.cos(lat2)
x = math.cos(lat1)*math.sin(lat2) - math.sin(lat1)*math.cos(lat2)*math.cos(dLon)
bearing = math.degrees(math.atan2(y, x))
if bearing < 0:
bearing += 360.0
return bearing
class Wind(object):
'''a wind generation object'''
def __init__(self, windstring, cross_section=0.1):
a = windstring.split(',')
if len(a) != 3:
raise RuntimeError("Expected wind in speed,direction,turbulance form, not %s" % windstring)
self.speed = float(a[0]) # m/s
self.direction = float(a[1]) # direction the wind is going in
self.turbulance= float(a[2]) # turbulance factor (standard deviation)
# the cross-section of the aircraft to wind. This is multiplied by the
# difference in the wind and the velocity of the aircraft to give the acceleration
self.cross_section = cross_section
# the time constant for the turbulance - the average period of the
# changes over time
self.turbulance_time_constant = 5.0
# wind time record
self.tlast = time.time()
# initial turbulance multiplier
self.turbulance_mul = 1.0
def current(self, deltat=None):
'''return current wind speed and direction as a tuple
speed is in m/s, direction in degrees
'''
if deltat is None:
tnow = time.time()
deltat = tnow - self.tlast
self.tlast = tnow
# update turbulance random walk
w_delta = math.sqrt(deltat)*(1.0-random.gauss(1.0, self.turbulance))
w_delta -= (self.turbulance_mul-1.0)*(deltat/self.turbulance_time_constant)
self.turbulance_mul += w_delta
speed = self.speed * math.fabs(self.turbulance_mul)
return (speed, self.direction)
# Calculate drag.
def drag(self, velocity, deltat=None, testing=None):
'''return current wind force in Earth frame. The velocity parameter is
a Vector3 of the current velocity of the aircraft in earth frame, m/s'''
from math import radians
# (m/s, degrees) : wind vector as a magnitude and angle.
(speed, direction) = self.current(deltat=deltat)
# speed = self.speed
# direction = self.direction
# Get the wind vector.
w = toVec(speed, radians(direction))
obj_speed = velocity.length()
# Compute the angle between the object vector and wind vector by taking
# the dot product and dividing by the magnitudes.
d = w.length() * obj_speed
if d == 0:
alpha = 0
else:
alpha = acos((w * velocity) / d)
# Get the relative wind speed and angle from the object. Note that the
# relative wind speed includes the velocity of the object; i.e., there
# is a headwind equivalent to the object's speed even if there is no
# absolute wind.
(rel_speed, beta) = apparent_wind(speed, obj_speed, alpha)
# Return the vector of the relative wind, relative to the coordinate
# system.
relWindVec = toVec(rel_speed, beta + atan2(velocity.y, velocity.x))
# Combine them to get the acceleration vector.
return Vector3( acc(relWindVec.x, drag_force(self, relWindVec.x))
, acc(relWindVec.y, drag_force(self, relWindVec.y))
, 0 )
# http://en.wikipedia.org/wiki/Apparent_wind
#
# Returns apparent wind speed and angle of apparent wind. Alpha is the angle
# between the object and the true wind. alpha of 0 rads is a headwind; pi a
# tailwind. Speeds should always be positive.
def apparent_wind(wind_sp, obj_speed, alpha):
delta = wind_sp * cos(alpha)
x = wind_sp**2 + obj_speed**2 + 2 * obj_speed * delta
rel_speed = sqrt(x)
if rel_speed == 0:
beta = pi
else:
beta = acos((delta + obj_speed) / rel_speed)
return (rel_speed, beta)
# See http://en.wikipedia.org/wiki/Drag_equation
#
# Drag equation is F(a) = cl * p/2 * v^2 * a, where cl : drag coefficient
# (let's assume it's low, .e.g., 0.2), p : density of air (assume about 1
# kg/m^3, the density just over 1500m elevation), v : relative speed of wind
# (to the body), a : area acted on (this is captured by the cross_section
# paramter).
#
# So then we have
# F(a) = 0.2 * 1/2 * v^2 * cross_section = 0.1 * v^2 * cross_section
def drag_force(wind, sp):
return (sp**2.0) * 0.1 * wind.cross_section
# Function to make the force vector. relWindVec is the direction the apparent
# wind comes *from*. We want to compute the accleration vector in the direction
# the wind blows to.
def acc(val, mag):
if val == 0:
return mag
else:
return (val / abs(val)) * (0 - mag)
# Converts a magnitude and angle (radians) to a vector in the xy plane.
def toVec(magnitude, angle):
v = Vector3(magnitude, 0, 0)
m = Matrix3()
m.from_euler(0, 0, angle)
return m.transposed() * v
def constrain(value, minv, maxv):
'''constrain a value to a range'''
if value < minv:
value = minv
if value > maxv:
value = maxv
return value
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if __name__ == "__main__":
import doctest
doctest.testmod()