Further study of the optimisation of the tractive efficiency of all-wheel-drive vehicles

This paper examines the tractive efficiency of all-wheel-drive vehicles in general and the slip efficiency in particular. It focuses on the analysis of the conditions for achieving the optimal slip efficiency. Results of detailed theoretical analyses indicate that all drive wheels operating at the same slip will be the necessary and sufficient conditions for achieving the optimal slip efficiency, if their thrust-slip relationships are either linear or nonlinear with similar characteristics. If the thrust-slip relationships of the drive wheels are nonlinear with different characteristics, the optimal slip efficiency will be reached with the slips of the drive wheels not being equal. The basic findings of this investigation are substantiated with experimental data. The results of this study suggest that the requirement for all drive wheels operating at the same slip provides a reasonable basis for a practical control strategy of an active system to distribute torque (thrust) among the drive wheels to achieve the optimal (or close to the optimal) slip efficiency of all-wheel-drive vehicles under most operating conditions. Copyrigh