GPS-aided land-based navigation and precision farming applications: improving GPS accuracy by means of MEMS IMU and low-cost sensors

The main topic of this research was the use of low-cost GPS (Global Positioning System) for land-based navigation with particular attention to precision farming applications. In order to improve GPS solutions, the integration with additional sensors, such as magnetometers and IMU (Inertial Measurement Unit), was investigated. Those GPS, indeed, do not store any raw data but just provide a NMEA format data stream containing coordinates. They were obtained by a single point positioning based on code signal only. A solution to this problem still exists: it is obvious how such system could be improved by using a differential (DGPS or RTK) approach. Allowing to receive corrections, it would provide a decimeters or centimeters level of accuracy, respectively. The point is that it would not be anymore a low-cost system: the problem of achieving a sub-meter accuracy can be solve despite of a higher cost. The challenge is to find a cheaper solution and improve pseudorange-based GPS operating in a stand-alone mode. Concerning the application field, that is land-based navigation, some essential aspects still appear to be critical: just an example, a lot of unsolved inconveniences occur because of frequent GPS losses of lock in urban canyons.