Carrier-Phase DGPS Control of Farm and Vehicles for Closed-Loop Construction

Operating heavy equipment can be a difficult and very tedious task. Control of an agricultural tractor requires the continuous attention of the driver, and farmers often work long hours during critical times of planting and harvesting. Loaders and other ground vehicles are frequently used in situations that are unpleasant or even hazardous for a human operator. This paper explores the use of carrier-phase DGPS as the sole position and attitude sensor in closed-loop control of farm and construction vehicles. A land vehicle optimal control system was designed and simulated using realistic plant, sensor, and disturbance models. To validate this simulation, a GPS-equipped electric golf cart was driven to high accuracy under automatic steering control. Golf cart experimental data were examined in post-processing to determine the feasibility of on-line system identification with GPS.