InertialNav App Lite is an attitude estimator/indicator, with the following instruments:

• artificial horizon.
• altimeter
• compass (magnetic)
• speed meter (groundspeed, vertical speed)

A HUD mode allows using the application for augmented reality.

Real-time measurements and estimations can be exported to a text file for post-processing (e.g. into MATLAB, SciLab or Octave). Note: the Pro version allows sending those data through WiFi.

NOTE ABOUT THE FULL VERSION

The full version of this app includes:

• transmission of data (acceleration, gyro, etc.) over wifi,
• better estimation of the vertical speed with GPS measures included in the Kalman filtering*,
• better estimation of heading in magnetic perturbed environments,
• estimation of the position and velocity,
• ground track tool,
• Google Map inclusion,
• dashboard to print current data,
• multiple panes display on large devices.
• In the lite version, position data comes from GPS measurements only. Furthermore, the vertical speed is calculated from GPS measurements and can thus only be of limited accuracy.

HOW DOES IT WORK?

In real life environment, sensors tend to measure noises in addition to the physical quantity of interest. The current application provides an estimate of the attitude. To have the best estimation of the attitude an Extended Kalman Filter (EKF) is implemented. The filter's purpose is to reject all perturbations, but to do so efficiently, it needs different sources of measurments. Considering we are interested by the orientation, and your device is indeed an inertial measurement unit (IMU with gyroscopes, accelerometers and so on), using gyroscopes for angular velocity and a set of measurements from accelerometers and magnetometers, we can indeed estimate the attitude with our EKF. That is, to estimate the attitude, the EKF will sometimes discard information from the sensors that it deems unreliable or too noisy - it may sometimes favour the attitude measurements rather than the angular velocity integration and vice versa - to minimise the covariance of the error. Furthermore, quaternion formulation for the orientation makes the estimation very robust.

• IMPORTANT ** : depending on your device, please consider going through the covariance settings for best estimation of the attitude! The EKF may disregard the measurements if deemed unreliable. If YOU THINK the app does not use the gyroscopes, please CHECK the variance settings for the gyroscopes.

MINIMUM REQUIREMENTS

For best performances, accelerometers, gyroscopes and magnetometers must all be present on the device.

Optional requirements: GPS, camera.

(HeadUp Display will only be available when a camera is available)

The application is provided as-is, without any warranty. The application is not certified for navigation purposes by any agency or organisation.

If you find bugs, please report by email. Thanks!

Tested on Samsung Galaxy S2.