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The problem of vehicle stability in emergency maneuvers has attracted a lot of research effort recently. Perhaps the most effective contributions made in this area were devoted to the control of vehicle yaw rate either by active steering or differential braking control systems. Each control technique has its own limitations that make it ineffective in some particular situations. This paper introduces a combined steering and braking control strategy using a fuzzy logic inference system. The proposed controller uses the estimated coefficient of friction (μ) to organize the combined control action. Computer simulation using a comprehensive vehicle model is used to illustrate the strengths and limitations of various control strategies.

It is commonly accepted that the principal functions of an automobile suspension are to control low frequency rigid body motions, provide comfort to passengers, and to reduce tire normal force variation so that predictable handling is maintained. A good argument for reducing normal force variation is that in the extreme, if a tire is off the ground, it for certain cannot generate any lateral forces, and thus compromises lateral dynamics. The direct relationship between road holding and dynamic tire normal force variation is quantified sparsely in the literature. In this paper a relatively simple model is proposed which exposes how normal force variation at the front and rear directly affects the vehicle yaw rate and lateral acceleration. It is shown that normal force variation at the front has potentially the same effect on lateral dynamics as does the steering input.