## 1 Introduction  
The automobile is a typical complex system. Many parts of a vehicle are involved in the research of vehicle dynamics, and the performance of each part affects the performance of the whole vehicle in varying degrees [1]. An automobile system can be divided into several small systems. Overall vehicle performance can be improved by enhancing each small system from the perspective of reductionism. For cars, they should be regarded as a large system, and all their parts should be analyzed in a unified way. Moreover, a unified and global implementation scheme should be proposed and subsequently implemented to each subsystem holistically. The chassis system is an important assembly in automobiles that involves suspension, steering, braking, driving, and other subsystems with coupling relationship. The extensive use of underlying controllers may lead to functional conflicts between different chassis controllers and result in unnecessary expenses and the reduction of the control effect in the wide use of control systems and control technologies. Active control technology can greatly improve the control performance of all parts of the chassis system [2]. In 2006, a nonlinear constrained optimal allocation control method was proposed on the basis of the tire force distribution method and concept of friction circle [3]. [PERSON] et al. studied a hierarchical integrated control method for vehicle dynamics in which a sliding mode controller is used to obtain the total longitudinal force, total lateral force, and total yaw moment of a vehicle in the upper control layer; this approach distributes the force and torque of the body to the longitudinal slip ratio and side slip angle of the four tires [4]. [PERSON] and [PERSON] studied and designed a vehicle integrated control framework that comprehensively considers the control actuators of each system and proposed the concept of vehicle dynamics integrated control. The concept skips the traditional idea of electronic control system design and involves function based on control structure [5]. A logic control of active front wheel steering (AFS) and electronic stability system was studied by [PERSON] et al. in 2008 [6]. [PERSON] et al. established a coordinated control method for four-wheel driving force that is mainly used in four-wheel independent driving and four-wheel independent steering structures to minimize the energy loss of vehicle systems while improving their overall stability [7]. [PERSON] et al. also studied a new four-wheel angle assignment method for four-wheel independent steering electric vehicles by minimizing tire slip [8]. [PERSON] and [PERSON] used a hierarchical control system in which the maximum friction coefficient between the wheel and the road surface is adaptively controlled to minimize the output force of the controller [9]. A nonlinear vehicle dynamics model integrated with AFS, electronic stability control (ESC), and variable torque distribution was established by [PERSON] et al. [10]. A chassis control algorithm based on differential braking, front/rear traction torque, and active yaw moment control was proposed by [PERSON] et al. The results indicate that the control effect of the chassis control system is better than that of a sole bottom plate control system and that it can maximize speed and vehicle steering lateral stability [11; 12]. Through coordinated control with AFS, ESC, and active rear-wheel steering, [PERSON] observed the interaction among systems by using a variety of combinations and distributed wheel tire control force on the basis of inverse weighted pseudo control allocation. The Plackett-Burman method was used to analyze the sensitivity and check the influence of variable weights [13]. In the field of chassis control, suspension has been used to improve comfort. However, with the emergence of semiactive suspension and active suspension, the need to establish the status of suspension control with consideration of ride comfort and stability has increased.