The gyroscope continuously monitors angular rotations via another DCM (University of Cambridge, 2007) to track changes in heading. When a step is detected, distance traveled is calculated by applying the stride length of the user to the step taken.
The step detector begins counting steps by finding peaks in the accelerometer data, where each step taken produces a spike. This initial orientation serves as the origin to which future changes in location are added. When the app is started, it determines the user’s initial orientation relative to Earth by analyzing magnetic field and gravity data via a Direction Cosine Matrix (DCM) (Freescale Semiconductor, 2012).
The app also features a user interface that allows the user to create profiles and store tracking preferences such as stride length and step counter sensitivity. These components include a step counter, a compass, a data collector, a QR code scanner, a calibration mode, and an interactive graph. During each part, standalone app components were built to be later incorporated into the main project. The process of building the fully functional location tracker was split up into multiple parts.
Position Error Methods The app was developed using the Android Software Development Kit on the Android Studio Integrated Development Environment and tested on a Google Nexus 5 smartphone. The recalibration was akin to a waypoint system, whereby calibrating at each waypoint would reaffirm the correct location, and allow the error to be reduced to minimal levels. Without recalibration, error increased linearly with distance traveled. The error started to accumulate as the walk processed, and reset when the phone was recalibrated (Graph 3). The third walk covered a distance of 250 m in 4 separate segments (Picture 3), calibrating between each walk. The second walk was longer, covering a distance of 550 m (Picture 2), with an error accumulation of 45 m (Graph 2). The first walk covered a distance of 450 m (Picture 1), with the error accumulating to 35 m (Graph 1). The Dead Reckoning app offers a solution by using smartphone inertial sensors to track location, making the tracking process self-sufficient and non-reliant on GPS. There are many places where GPS signal is restricted, from underground tunnels, to inside large buildings, to outdoors if surrounded by large structures. GPS has made this job significantly easier, however the system is not perfect. Presentation on theme: "Dead Reckoning, a location tracking app for Android™ smartphones Nisarg Patel Mentored by Adam Schofield and Michael Caporellie Introduction Results (cont.)"- Presentation transcript:ġ Dead Reckoning, a location tracking app for Android™ smartphones Nisarg Patel Mentored by Adam Schofield and Michael Caporellie Introduction Results (cont.) Results (cont.) Many modern conveniences rely on the ability to pinpoint accurate location.
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