Key differences from the <a href="https://github.com/maddevsio/mad-location-manager" >old version</a>

Rewrote filter using C++ from scratch
All matrix operations are implemented with libeigen
All geographic operations, distance calculations, etc., are made with GeographicLib
Changed process noise matrix (Q). See the math behind it here
Fixed bug related to estimate covariance matrix (P)
Changed the method of how ENU (east-north-up) acceleration is calculated. Migrated from the rotation matrix to quaternions

Requirements

cmake
git
pkg-config
gkt4
libshumate

Project structure

Filter contains Kalman filter implementation itself

How to build filter

Thes is CMake-based project. To build it, use the following commands:

cmake -B build

cmake --build build -j12

Then run build/mlm_visualizer

How to run tests

cmake -B build

cmake --build build -j12

Then run build/filter_unit_tests

How to generate documentation

cmake -B build

make -C build docs

Then find documentation in build/docs folder

How to use filter

See filter/mlm.h and filter/sensor_data.h for details. But overall, the process looks like this:

Create the MLM object mlm.
When the accelerometer vector in ENU is ready, feed it to mlm (bool process_acc_data(const enu_accelerometer &acc, double time_sec);)
When the GPS coordinate is ready, feed it to mlm (void process_gps_data(const gps_coordinate &gps, double time_sec);)
After receiving each GPS coordinate, get the filtered coordinate from mlm (gps_coordinate predicted_coordinate() const;)

An example of all steps described above can be found here An example of how to build Android is in wiki

The roadmap

[x] Implement Kalman filter
[x] Fix bugs
[ ] Clear and clean documentation, probably doxygen
[ ] Refactor and optimize
[ ] Add accelerometer bias into model (probably it's not necessary, because filter shows worse results than without bias in model, but we need to try to tune bias level)

License

MIT License

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.