2005 Volume 67 Issue 5 Pages 86-92
A two-hierarchy fuzzy controller (FC) and a new path tracking method were developed to guide the tractor along arbitrary paths on sloped terrain. The upper level FC utilized the terrain slope and vehicle posture to determine the types of processes in the lower level FC; whereas the lower level FC used the lateral deviation and the orientation error to obtain the optimal steering angle change for autonomous navigation. In the designed path tracking method, both the location and orientation of the navigation points were employed to determine the current steering angle for vehicle motion. Field tests showed that for rectilinear paths the average tracking error was -0.02m, with standard deviation of 0.06m, and for the curved paths, the maximum lateral deviation and the maximum orientation error were less than 0.08m and 11° respectively at the completion of these paths.
