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Autonomous Traveling of Off-road Vehicles along Rectangular Path on Slope Terrain

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  Pp. 412-421 in Automation Technology for Off-Road Equipment, Proceedings of the July 26-27, 2002 Conference (Chicago, Illinois, USA)  701P0502.(doi:10.13031/2013.10031)
Authors:   M.A. Ashraf, R. Torisu, and J. Takeda
Keywords:   Autonomous travel, Off-road vehicle, Rectangular path, Slope terrain, Optimal control, Neural Network, and Genetic Algorithm

An automatic off-road wheeled-vehicle guidance system has been developed to navigate the vehicle along rectangular path on sloped terrain. For this purpose a neural network (NN) vehicle model was proposed to obtain relationship between the steerage and behavior of tractors on sloped terrain. An optimal control theory is applied to design a steering controller for the rectilinear motions on sloped terrain, where genetic algorithm was used to optimize the steering angle. A coordinate transformation system was also designed to determine the vehicle position with respect to the rectangular path. Feedback control method was applied for the rectilinear motions along the contour lines, uphill and downhill directions; and feedforward control method was applied for the quarter turns of the rectangular path. Finally the feedback and feedforward control methods were compounded to guide the tractor along the rectangular path. An autonomous traveling test was conducted along a 30x15 m rectangular path on in excess of 15º sloped terrain. Results showed that average of the mean and standard deviations of lateral displacements and heading angles for the motions along four directions of the rectangular path were 0.05 m, 0.06 m, -0.1º and 2.3º respectively.

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