Review of Vehicle Active Safety Systems and Their Coordinated Control

Abstract

Background: It is obvious that the safety concern associated with a vehicle is greatly valued by all, whether it is now or in the future, the automobile safety issue is the hotspot and the focus of the research by experts and scholars. The continuous increase in car ownership brings convenience to people's life and also poses a threat to people's life and property. Vehicles’ active safety system is the hotspot of current research and development, which plays an important role in automobile safety. Firstly, the vehicle’s active safety technology and its development are introduced. Then, a review is carried out examining the Anti-Lock Brake System (ABS), the Electronic Brake force Distribution (EBD/CBC), the Brake Assist System (BAS/EBA/BA), the Traction Control System (TCS/ASR), the Vehicle Stability Control (VSC/ESP/DSC), etc. At present, there are many patents on the control of each subsystem, but few patents on the integrated control for the active safety of vehicles. Objective: The main contents of this paper are as follows: the control strategies and methods of different active safety systems, the strategies to improve the stability of a vehicle control system and ensure the effectiveness of active safety system control. It provides a reference for the development of active safety control technology and patent. Methods: Through the analysis of different control algorithms and control strategies of Anti-lock and braking force distribution systems, it is pointed out that the switching of EBD/ABS coordinated control strategy according to slip rate can make full use of slip rate and road adhesion coefficient to improve the safety of the system. For the BAS, the slip problem is solved through the combination of the Mechanical Assistant Braking System (MABS) and Electronic Braking Assistant (EBA) system by measuring the distance and the speed of the vehicle ahead. The optimal slip rate control is realized by different control algorithms and control strategies of the traction control system. It is pointed out that the adaptive fuzzy neural controller should be used to control the yaw angular velocity and centroid side angle of the Electronic Stability Program (ESP), which has a good effect on maintaining vehicle stability. A sliding mode variable structure controller combined with constant speed control and law control is used to control the yaw moment. Results: Through the coordinated control strategy of EBD/ABS, the slip rate and road adhesion coefficient were fully utilized by switching according to the slip rate. The problem of the sliding slope was solved by MABS with EBA system. The ESP should use an adaptive fuzzy neural controller to control the yaw angular velocity and centroid side angle, and adopt the joint sliding mode variable structure controller which combines the ABS control and the yaw moment control. Through the optimal control theory, the coordinated control of each subsystem can significantly improve driving stability, riding comfort, fuel economy and so on. Conclusion: This study adopts different control strategies and control algorithms for different active safety control systems and makes full use of the tire-road friction coefficient and slip ratio optimal slip ratio. These focus on accurate control of control variables such as yawing angular velocity, centroid side-slip angle, yawing moment and finally ensure the vehicle braking stability, robustness of the controller and the lateral stability of the vehicle.