Package: ins-nav
ins_navThis library is written independent of any specific IMU. The idea is you pass in the appropriate
measurements and error terms from your IMU and get the desired output.This is still under heavy developmentReference FramesECI: Earth-centered Inertialis an
inertial frame where Newton's laws of motion apply. It has its origin at the center of the
Earth with:x-axis in the direction of the vernal equinoxz-axis is parallel to the rotation of the Earthy-axis completes the right-handed coordinate systemECEF: Earth-centered, Earth-fixedhas the same origin
as ECI, but rotates with the Earth and the x-axis points towards the zero/prime
meridian. The ECEF frame rotates at 7.2921E-5 rads/sec with respect to the ECI
frameLLA(H): Latitude, Longitude, Altitude(Height)is similar to the ECEF frame, but
is the frame historically used for GPS navigationWGS84wgs=WGS84()# here are a bunch of useful constants in WGS84 classwgs.rf=298.257223563wgs.f=1/self.rfwgs.a=6378137.0wgs.b=self.a-self.a*self.fwgs.e=np.sqrt(1-(self.b**2/self.a**2))wgs.r=(2*self.a+self.b)/3wgs.rotation_period=23*3600+56*60+4.09053wgs.rate=7.2921157e-5# Rotation rate of Earth [rad/s]wgs.sf=1.2383e-3# Schuller frequency# translate ecef(x,y,z) <=> llh(lat,lon,alt)wgs.ecef2llh(loc)wgs.llh2ecef(loc)wgs.gravity(lat)# gravity changes by latitude[deg]wgs.radius(lat)# Earth's radius changes by latitude[deg]wgs.haversine(a,b)# calculates distance between locations a and bNavigation FramesWhile ECEF can be used to navigate the globe, often, you only need to travel 100's of meters
or kilometers. Thus a local navigational frame that is tangental to the curvature of the
Earth is more useful (and intuitive). Two common ones are:ENU: East North Upa local navigation frame, whereupand the z-axis align, but clockwise right turns
are negativeNED: North East Downa local navigation
frame, whereupand the z-axis are opposite, but the direction of right (clockwise)
turns are in the positive direction and is the standard vehicle roll-pitch-yaw frameref=(40,-90,100)# origin of local frame (lat[deg], lon[deg], altitude[m])frame=NavigationalFrame(ref)# allof these will calculate position relative to your local# frame originloc=[x,y,z]frame.ecef2ned(loc)frame.ecef2enu(loc)frame.ned2ecef(loc)frame.enu2ecef(loc)frame.enu2ned(loc)frame.ned2enu(loc)Other Good Navigation Librarieslat_lon_parserallows you to convert between
measurements formats like-45 deg 12' 36.0 sec,45.21 W, and-45.21easilynvectorhas a lot of capabilitynavpyappears to be simple grad student work but code is well referenced (BSD)navigationdoes GPS navigation and way
pointsThe MIT License (MIT)Copyright (c) 2016 Kevin J. WalchkoPermission is hereby granted, free of charge, to any person obtaining a copy of
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