A Study of Cornering Braking Control Strategy Based on Road Identification
Identification of road friction is a prerequisite to optimize vehicle cornering braking control strategy. A maximum aligning moment method is proposed to estimate road friction coefficient using the sensors equipped with the steering system. Based on the
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Abstract Identification of road friction is a prerequisite to optimize vehicle cornering braking control strategy. A maximum aligning moment method is proposed to estimate road friction coefficient using the sensors equipped with the steering system. Based on the hardware and the control logic of anti-lock braking system (ABS), an enhanced stability braking system (ESBS) is designed to improve the performance during cornering braking. Simulation and experimental results show that the estimation algorithm can identify changes of road conditions precisely and the control strategy improves braking efficiency and lateral stability of the vehicle, and thus has a high value of practical application.
Keywords Road identification Brush tire model Cornering braking Slip ratio Turning radius
1 Introduction The principle of Anti-lock braking system (ABS) is to control the slip ratio of each wheel near the corresponding slip ratio of the maximum adhesion coefficient (sl), as a result of which the vehicle will obtain maximum braking force and good lateral stability. However, sl is not a constant, which may change with the variety of road conditions [1]. Burckhardt formula [2] depicts the relationship between F2012-F08-014 X. Guan (&) Y. Li T. Ba J. Zhang School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, China
SAE-China and FISITA (eds.), Proceedings of the FISITA 2012 World Automotive Congress, Lecture Notes in Electrical Engineering 197, DOI: 10.1007/978-3-642-33805-2_55, Ó Springer-Verlag Berlin Heidelberg 2013
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slip ratio and the adhesion coefficient of some typical roads, and the dry asphalt road, wet asphalt road and ice or snow covered road are about 0.15, 0.1 and less than 0.05, respectively, so road identification is helpful for ABS to make the best use of the adhesion between tires and road. Besides, because of the longitudinal and lateral load transfer, the braking force and lateral force of each wheel vary greatly during cornering braking. This phenomenon may yield a large yaw moment which is possible to reduce the lateral stability of the vehicle and increase the opportunity of an accident. In order to improve the performance of ABS, it is necessary to design a control strategy to maintain the lateral stability of a vehicle during cornering braking. In recent years, so many papers, in allusion to the identification of road friction and cornering braking control strategy, have been published. Mauer [3] proposed a method for road identification by taking advantage of brake pressure, slip ratio and brake deceleration, however, an acceleration transducer was needed according to the method, which not only increased costs, but also caused a larger error. Ahn [4] and Hsu [5] proposed to establish a nonlinear observer to estimate road friction, but it is hard to estimate the value of road friction promptly and accurately when the road condition changes continually. Li [6] proposed a cornering braking control strategy based on fuzzy control, but this ap
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