Vehicle dynamic performance is predominantly controlled by tire dynamic characteristics through the forces and moments generated at the tire-road contact patch. The control of the tire vertical force can improve the vertical vibration characteristics and ride behavior. The control of the tire lateral forces usually benefits the vehicle stability and handling characteristics, and an optimized tire longitudinal force control can improve braking performance.  Consequently, in the case of modern day vehicle control systems employing a feedback control structure, a real-time estimate of the tire-road contact parameters is invaluable for enhancing the performance of the chassis control systems such as anti-lock braking systems (ABS) and stability control systems (VSC).

                At present, the commercially available tire monitoring systems are not equipped to sense and transmit high speed dynamic variables used for real-time active safety control systems. Hence, today’s vehicle control systems are limited by the lack of knowledge of critical tire-road states (i.e. the kinematic conditions of the tire to its dynamic properties). From aforementioned discussion, it is clear that some method of estimating tire-road contact parameters would be greatly desirable. This need for an online tire monitoring system has stimulated the development of certain sensor based advanced tire concepts, capable of giving direct measurements of the tire-road contact parameters. Considering the strong interdependence between the operating road surface condition and the instantaneous forces and moments generated; this real time estimate of the tire-road contact parameters is expected to play a pivotal role in improving the performance of a number of existing vehicle control systems, and is also expected to spur the development of a new generation of vehicle control systems with modified control strategies.

                 This study specifically investigates how tire sensed information could be used to improve the performance of certain vehicle control systems that are becoming increasingly available in the market today. More specifically, the control systems investigated include: (i) anti-lock brake system (ABS), (ii) vehicle stability control system (VSC), and (iii) collision mitigation brake system (CMBS). The first part of this study was devoted to the identification of a sensing technology suitable for tire applications. The next phase of the study focused on the development of sensor feature extraction methodologies of acceleration signals coming from the sensors fixed to the tire innerliner, with the final objective of developing a sensorized tire system capable of providing real-time information about the tire-road contact parameters. The identified sensing parameters/features of a tire include: tire load, slip angle, slip ratio and tire-road friction coefficient. The final phase is focused on the possibility of enhancing the performance of the aforementioned control systems by using the additional information provided by the smart tire system. The paper is concluded by providing and discussing the results of these proposed algorithms.

 

Keywords:  Intelligent/smart tire, vehicle dynamics control, anti-lock brake system (ABS), collision mitigation brake system (CMBS), vehicle stability control system (VSC)