diff --git a/How does it work.markdown b/How does it work.markdown deleted file mode 100644 index 8778eca..0000000 --- a/How does it work.markdown +++ /dev/null @@ -1,18 +0,0 @@ -How do Extended Kalman Filters work? -====== -Let's say you've grown bored of re-watching Battlestar Galactica on DVD and you're looking for a challenge. You decide you want to figure out the pitch and roll of your RC aircraft using nothing more than a 3-axis gyroscope, a 3-axis accelerometer and a differential pressure sensor for airspeed. - -In a perfect world and with a gyroscope with infinite precision you could simply accumulate the readings from the gyroscope: if you're reading at 50Hz (50 times per second), you would take the reading and multiply it by a fraction to convert from degrees per 1/50th of a second to per second. (Footnote: That fraction is called "dt". Hopefully you've taken calculus and understand integrals and that dt refers to a variable with respect to time.) If you were to rolling to the right at a constant 15 degrees per second, you would know what your roll is given the time. At half a second you'd be at +7.5 degrees and at 3 seconds you'd be at +45 degrees. That's essentially what inertial navigation is doing. - -There's a few problems though that complicate things: - - * Gyros aren't infinitely precise nor you can add up every instant in time. This means that somewhat quickly the accumulated readings from the gyro will differ from reality. - * Sensor noise (readings from a sensor are essentially a normal distribution around the correct value) - -In order to make our lives easier when estimating the pitch and roll we're going to model the flight dynamics of the aircraft. While this limits how the aircraft can fly it means the estimation is easier and more accurate when we place limits and rules on how we can fly. - - - - - -So yeah I didn't get the time to finish this…is this heading the right direction? Help finish this! \ No newline at end of file diff --git a/LICENSE b/LICENSE index c990a69..887566f 100644 --- a/LICENSE +++ b/LICENSE @@ -1,22 +1,177 @@ -Copyright (c) 2010 Tim Trueman and Ryan Beall - -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. 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It provides realtime estimates to allow for higher-level navigation software to be developed. + +For installation instructions (you _will_ need to follow these if you want to get it working), more details and screenshots go to [http://dronedynamics.com/polaris/](http://dronedynamics.com/polaris/). + +## Basics + +Polaris is a software INS that runs against X-Plane out of the box but can also be used on real hardware. + +Polaris is designed to take the following inputs: + +- 3-axis accelerometer +- 3-axis gyro +- 3-axis magnetometer (including [magnetic declination](http://en.wikipedia.org/wiki/Magnetic_declination) lookup table) +- Static air sensor (altitude) +- Differential air sensor (indicated airspeed) +- GPS +- Various temperatures (both on the sensors and ambient) + +And turn those inputs into a realtime probabilistic model with the following estimates: + +- Orientation (pitch, roll, and yaw) +- Position (longitude, latitude, and altitude) +- Speeds (indicated airspeed, true airspeed, speed over ground) +- Wind (x/y/z axis windspeed estimates which help make a more accurate [dead-reckoning](http://en.wikipedia.org/wiki/Dead_reckoning) estimate) + +## Features + +Polaris is able to build and maintain its realtime probabilistic model primarily using an (extended Kalman filter](http://en.wikipedia.org/wiki/Extended_Kalman_filter) (EKF). There are _two_ major steps to the EKF: **predicting** your current state and **updating** your model based on what actually happened. + +Right now Polaris uses [Euler angles](http://en.wikipedia.org/wiki/Euler_angles) but in the future it may use [quaternions](http://en.wikipedia.org/wiki/Quaternion). + +More to come in this section… + +### Todo + +1. Local magnetic declination lookup table +2. Get course over ground working (emulated or hpath) +3. Get cpress working (true airspeed / indicated airspeed ratio) +4. Code up alternate algorithms such as DCM and benchmark it against the EKF +5. Quaternion-based EKF +6. More advanced display/logging +7. Clean up website, installation instructions +8. Make a screencast for setting it up and explaining it +9. Port to other platforms +10. Email Austin Meyer (X-Plane) and see if he's willing to include raw magnetometer values +11. Once all the algorithms are verified (including a write-up on the testing perhaps), introduce sensor noise +12. Your idea here ✈ [tim@dronedynamics.com](mailto:tim@dronedynamics.com) + +## Issues + +Have a bug or feature request? Please create an issue here on GitHub! + +https://github.com/dronedynamics/polaris/issues + +## Authors + +**Ryan Beall** + +**Tim Trueman** + ++ http://twitter.com/timtrueman ++ http://timtrueman.com/ ++ http://github.com/timtrueman + +**Add your name above this line if you send a pull request…** + +## License + +Copyright 2011 Tim Trueman and Ryan Beall + +Licensed under the Apache License, Version 2.0: http://www.apache.org/licenses/LICENSE-2.0 \ No newline at end of file diff --git a/Readme.markdown b/Readme.markdown deleted file mode 100644 index c259c60..0000000 --- a/Readme.markdown +++ /dev/null @@ -1,20 +0,0 @@ -Shumai -====== -Shumai (pronounced "Shoe-my") is _the_ open-source inertial nagivation software for fixed-wing aircraft. It provides realtime estimates to allow for higher-level navigation software to be developed. - -For installation instructions (you _will_ need to follow these if you want to get it working), more details and photos go to [http://dronedynamics.com/shumai/](http://dronedynamics.com/shumai/). - -Todo -====== -1. Pull in local magnetic declination -2. Get course over ground working (emulated or hpath) -3. Get position estimation working -4. Code up DCM and benchmark it against the EKF -5. More advanced display (separate things out into sensors, estimates and truth/performance data) -6. Clean up website, installation instructions -7. Make a screencast for setting it up and explaining it -8. Port to other platforms -9. Evaluate options for avoiding singularities -10. Email Austin Meyer and see if he's willing to include raw magnetometer values -11. Once all the algorithms are verified (including a write-up on the testing perhaps), introduce sensor noise -12. Your idea here ✈ [tim@dronedynamics.com](mailto:tim@dronedynamics.com) \ No newline at end of file