| Real-time centimeter-level navigation has countless potential applications in land vehicles, including precise topographic field mapping, runway snowplowing in bad weather, and land mine detection and avoidance. Perhaps the most obvious and immediate need for accurate, robust land vehicle sensing is in the guidance and control of agricultural vehicles.; Accurate guidance and automatic control of farm vehicles offers many potential advantages; however, previous attempts to automate these vehicles have been unsuccessful due to sensor limitations. With the recent development of real-time carrier-phase differential GPS (CDGPS), a single inexpensive GPS receiver can measure a vehicle's position to within a few centimeters and orientation to fractions of a degree. This ability to provide accurate real-time measurements of multiple vehicle states makes CDGPS ideal for automatic control of vehicles.; This work describes the theoretical and experimental work behind the first successfully demonstrated automatic control system for land vehicles based on CDGPS. An extension of pseudolite-based CDGPS initialization methods was explored for land vehicles and demonstrated experimentally. Original land vehicle dynamic models were developed and identified using this innovative sensor. After initial automatic control testing using a Yamaha Fleetmaster golf cart, a centimeter-level, fully autonomous row guidance capability was demonstrated on a John Deere 7800 farm tractor. |
