Control of the wheel driving forces as the basis for controlling off-road vehicle dynamics

摘要

Running abilities of an off-road, all-wheel-drive vehicle depend considerably not only on total traction effort but also on its distribution among the drive wheels. This distribution is largely determined by mechanisms and systems installed in power dividing transmission units. These are interwheel differentials, interaxle reduction gears, and transfer cases. To control the wheel driving forces for obtaining the optimum vehicle properties, a more creative and efficient way to design wheel drive systems and to control vehicle running abilities is being proposed. Optimization criteria for the tractive and velocity properties, fuel consumption, turnability, and ride stability of a vehicle have been used for the mathematical optimization of the wheel driving forces. The vehicle is modeled in motion with taking into account the kinematic requirements. Such optimal wheel driving forces create a basis for synthesizing control laws necessary for designing the optimum wheel drive mechanisms and systems for the vehicle. The paper presents a mathematical model of an eight- wheel-drive vehicle in motion, allowing a researcher to optimize those forces, presents the objective functions, and also gives the algorithm for computing the optimal wheel forces. The results of computation are also given. These represent the optimal distributions of the driving forces among the drive wheels, an analysis of the criteria of the vehicle's properties, and fundamentals for building a logical algorithm to control the wheel driving forces.