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Distribution of traction forces among driving wheels is one of the main factors governing the performance of a highway truck during acceleration and braking on varying macro and micro road surface conditions. Comprehension of the interaction between wheels and road surface provides a profound systematic way to simulate a truck's motion and design required components for the optimal performance. The development of electronic technologies has created the pre-conditions necessary to develop systems with controlled parameters. However, to realize the pre-conditions, vehicle dynamics problems have to be formulated and solved for both optimization and control. Many different approaches emerged with the aid of electronics to control the circumferential wheel forces (wheel torque) by restricting wheel slip. A part of such systems has been named as Acceleration Slip Regulation (ASR) and Anti Slip Differentials (ASD).

Mass and geometric parameters of all-wheel drive off road vehicles, such as coordinates of the center of gravity and arrangement of the wheels, have been obtained to satisfy cross-country mobility profiles that reduce the dynamic normal loads on the running gear system. However, the influence of these parameters on tractive properties for basic cross-country mobility of vehicles receives less attention. The authors have developed a new method for determining mass and geometric parameters that provides optimal tractive properties for basic cross-country mobility of off-road vehicles. The methodology is realized using a mathematical model of a 6WD tractor on a deformable road surface. The mass and geometric parameters are achieved by optimizing the tractive efficiency function to provide the best transport efficiency on all running gears.

To develop better performing vehicles, for ground transportation, it is necessary to improve the theory in vehicle dynamics for choosing suitable mass and geometric parameters for highway as well as for off road trucks. A new approach is required for choosing such optimal mass and geometric parameters. The present paper is devoted to this problem. A new method for synthesis of mass and geometric parameters is introduced here. The method allows us to synthesize the parameters in such way as to provide a vehicle with the best transport efficiency under various road surface conditions. Constraints such as limitations on these parameters, vehicle running modes, mass and geometric parameters are included in the model. Furthermore other constraints for vehicle running abilities which are dependent on mass and geometric parameters, as well as an algorithm for synthesizing mass and geometric parameters are also included in the paper for pre-optimization process.