A differential kinematic method for application of gps in its

We introduce a new method that performs accurate sensing of a vehicle position within highway lanes. The method would serve as a part of a Driver Assistance System (DAS) on specialty highway maintenance vehicles, such as snowplows. DAS will provide the operator of the vehicle with precise absolute position and lane departure warnings. The method is also explored as the most appropriate method for the purpose of vehicle automatic lateral control on the Automated Highway System (AHS) lanes. Previously, proposed methods for lane sensing are based on pavement magnetic marker sensing, a vehicle vision system, or DGPS (Differential Global Positioning System). The criteria in choosing the prevailing method for DAS or AHS is based on accuracy, implementation cost in the highway and vehicle infrastructure, and reliability in all conditions. The new method, IS-DGPS (In-Situ DGPS), is based on the use of GPS along with discrete reference markers (e.g. magnetic nails) placed on the roadway with a spacing of three or more seconds of traveling time. With IS-DGPS, the vehicle's receiver generates the GPS, differential corrections, needed for accurate positioning, using the road markers instead of relying on ground base stations and a wireless communication link, as in the case of DGPS. IS-DGPS positioning formulation is developed. Experimental results show its accuracy in determining the vehicle's position. Robustness of the method is discussed. An improved approach of IS-DGPS, using a multi-antenna receiver and GPS relative positioning, is presented.