Sentinel GPS Unit

The Sentinel system utilizes GPS, when available, to track personnel outdoors. Stand alone GPS is not very accurate, especially when tracking personnel in an unknown location. Therefore, computer algorithms must be implemented to bound the error.

Wikipedia Article on GPS accuracy

Our GPS unit is interfaced to the Sentinel system using a GPS Adapter developed by TRX Systems to be Plug-and-Play compatible with the Sentinel motherboard.

Various tests were performed with the Sentinel System. It uses complex algorithms to create an accurate position estimate by utilizing GPS and INU data. Screen shots comparing tracking with stand alone GPS with the Sentinel Fusion Algorithm can be seen below.

Figure 1: Fusion angle estimates the door location exactly on entering the test building.

Figure 2: After traversing an entire building, the fusion angle estimates the exit door location exactly.

Figure 3: The stand alone position estimate of GPS is poor.

Figure 4: After walking through the test building, GPS picks up again about 10 meters away from actual door location and requires time to regain position accuracy.

Figure 5: A full path comparison between stand alone GPS and the Sentinel GPS-INU Fusion.