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The investigation is concerned with dependencies between a friction coefficient of the tire with a road, μ, and wheel slip, s. The analysis of μ-s-dependencies is given in the paper. The conventional approach to their presentation contains some discordance with real physical processes. On the basis of the external friction theory it is possible to offer another concept of potential μ-s-curves. The potential μ-s-curve is a function of the deformative, adhesion and transverse components of tire grip, the absolute slip velocity and the road reaction. Over the interrelation character of the given components it is possible to evaluate a current road-operational situation. In addition the recommendations for practical use of the potential μ-s-dependencies for the Systems of Active Safety are given.

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.

In modern automotive industry is reshaped the new class of devices - intellectual systems of active safety (SAS). Their problem is safety control of the automobile movement by adequate reacting on suddenly changed road conditions and driver operating. The reliability of operation and the correctness of solutions for SAS are built up at the stage of its designing by synthesizing flexible, stable algorithm and creation of the informational-executive instrumentation for the intellectual control by automobile wheel. The statistical analysis of the friction arguments in the system “wheel - road”, held by the writers, has allowed to work out concept of preextreme control for SAS, which one makes possible to adapt for a flowing state of a road adjustment process by move of a wheel in the field of small slip (s=0,01 … 0,1). At the expense of this slip area is possible to avoid loss of controllability even at availability of a side withdrawal of a wheel.