Low Cost Augmentation of GPS for Improved Navigation

Abstract

Problems arising from use of a single navigation system include inaccuracy and poor reliability. Capabilities of each of three common navigation systems, the Global Positioning System (GPS) , Inertial Navigation System (INS), and Dead Reckoning (DR) are strong in some aspects, but weak in others. The absolute error of GPS is constant and relatively small (95% confidence: 80 meters), but the estimate can black out at times due to signal blockage. INS error is initially small, but increases exponentially over time; it can provide its estimate 100% of the time. Dead Reckoning sensors are inexpensive, but their accuracy can be limited. These sensors can work together to outperform any single system. This project seeks to make integration of these and other navigational sensors accessible to most consumers – and eventually to new applications. This is possible with an integrated navigation system, the physical goal of the project. The proof of concept is a bicycle equipped with a GPS and other sensors as well as a portable computer. The system showed that short term and long term improvements are realizable using sensors which cost $165: speedometer, compass, and gyro. Accuracy for the integrated system was seven times better than GPS for a 7.5 minute, approximately 2 kilometer course with one GPS blackout. Cumulative error for the integrated system was 27 meters; GPS error was 185 meters.