Chassis integrated control can significantly improve vehicle handling stability and comfort. Because of the complexity of the problem, it has attracted significant research attention. We built a vehicle nonlinear dynamic model with multi‐degree freedom, including body movement, wheel movement, and electronically controlled hydraulic power steering system. We compared the magic formula tire model, Dugoff tire model, brush tire model, and LuGre dynamic friction tire model and steady model. The precision of the model was verified by a comparison between simulation results and the real vehicle test results. Then, based on the vehicle dynamics model, an AFS (active front steering) controller was designed based on sliding mode variable structure control, and an AFS and ESP (electronic stability program) integrated coordination controller was proposed. Finally, based on the nonlinear tire model and multi‐DOF (degree of freedom) vehicle model, sinusoidal and step steering angle input simulation analysis was proposed on different road friction coefficients. The results show that the vehicle has better response characteristics with coordinated control strategy when compared with AFS and ESP only control. The evidence suggests that the proposed integrated control system in this paper can improve vehicle stability and safety.
Background: All the time, the safety of vehicle has been valued by all the world's parties, whether it is now or in the future, the automobile safety issue is the hotspot and focus of the research by experts and scholars both at home and abroad. The continuous increase of car ownership brings convenience to people's life and it also poses a threat to people's life and property security. Objective: Vehicle active safety system is the. hotspot of current research and development, which plays an important role in automobile safety. Through the analysis of patents and references, understand the development of an active steering system.In order to improve the development efficiency of active steering system, the paper proposes a feedback control method of front wheel angle. Methods: Based on yaw velocity and center of mass side angle, the Active Front Steering (AFS)model is established respectively by fuzzy control and sliding mode control under the establishment of seven degrees of freedom vehicle dynamics model and Dug off tire model. Results: The simulation results show that both the control algorithm of sliding mode control and fuzzy control can improve the handling stability of vehicle steering on high adhesion coefficient road surface. On the low adhesion coefficient road, the control effect of slide mode control is more ideal while fuzzy control caused larger oversteer. Conclusion: The simulation results show that the control effect of sliding mode is superior to fuzzy control.
Background: All the time, the safety of the vehicle has been valued by all the world's parties, whether it is now or in the future, the automobile safety issue is the hotspot and focus of the research by experts and scholars. The continuous increase of car ownership brings convenience to people's life and also poses a threat to people's life and property security. Vehicle active safety system is the hotspot of current research and development, which plays an important role in automobile safety. Firstly, the vehicle active safety technology and its development situation was introduced, then Ref. review was carried out about Anti-Lock Brake System (ABS), Electronic Brake force Distribution (EBD/CBC), Brake Assist System (BAS/EBA/BA), Traction Control System (TCS/ASR), 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, how to improve the stability of vehicle control 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 Mechanical Assistant Braking System (MABS) and Electronic Braking Assistant (EBA) system by measuring the distance of the vehicle ahead and the speed of the vehicle ahead. The optimal slip rate control is realized by different control algorithms and control strategies of 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 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 approach 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 slip rate. The problem of sliding slope is solved by MABS with EBA system. The ESP should use 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 the driving stability, riding comfort, fuel economy and so on. Conclusion: This adopt different control strategy and control algorithm for different active safety control system and make full use of tire-road friction coefficient and slip ratio optimal slip ratio, then it realized 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 vehicle.
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