ins-nav 0.6.0

A library to do inertial navigation

ins_nav

This 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 development

Install

The suggested way to install this is via the pip command as follows:

pip install ins_nav

Development

To submit git pulls, clone the repository and set it up as follows:

git clone https://github.com/MomsFriendlyRobotCompany/ins_nav
cd ins_nav
poetry install

Usage

• ins_nav.wgs84 contains a bunch of useful constants: semi-major axis, gravity, etc
• ins_nav.ahrs creates an attitude and heading reference system (AHRS) using accelerometers, gyroscopes, and magnetometers
• TiltCompensatedCompass contains the mathematics of an IMU with accelerometers, gyroscopes, and magnetometers
• ins_nav.transforms has a bunch of reference frame conversions: ecef2llh, llh2ecef, etc

Transforms (in work)

Earth Centered Frames

• ECI: Earth-centered Inertial is 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 equinox
  • z-axis is parallel to the rotation of the Earth
  • y-axis completes the right-handed coordinate system
• ECEF: Earth-centered, Earth-fixed has 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 frame
• LLA(H): Latitude, Longitude, Altitude(Height) is similar to the ECEF frame, but is the frame historically used for navigation

Navigation Frames

• ENU: East North Up a local navigation frame, where up and the z-axis align, but clockwise right turns are negative
• NED: North East Down a local navigation frame, where up and 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 frame

Other Good Navigation Libraries

• lat_lon_parser allows you to convert between measurements formats like -45 deg 12' 36.0 sec, 45.21 W, and -45.21 easily
• nvector has a lot of capability
• navpy appears to be simple grad student work but code is well referenced (BSD)
• navigation does GPS navigation and way points

Todo

• extended kalman filter
• navigation equations
• error model

Change Log

Date	Version	Notes
2020-03-28	0.6.0	moved to poetry
2019-07-05	0.5.1	cleanup and new functions
2017-07-07	0.0.1	init

The MIT License (MIT)

Copyright (c) 2017 Kevin J. Walchko

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.