Research On Control Algorithm And Performance Evaluation Method Of Vehicle Electronic Stability Program

Control principle of ESP (Electronic Stability Program) is to control the dynamics of vehicle when it is in the quasi-steady state, preventing the vehicle from getting into the unstable state that is uncontrollable. Maneuverability of vehicle with the assistance of ESP under extreme condition conform with the normal situation, which is the primary function of ESP. Therefore, the lost of stability caused by sudden change of vehicle dynamics can be avoided, making the driving more predicable with the driving experience in the linear region. Because of the improving of vehicle safety by ESP, the control algorithm design and performance evaluation of EPS system have been developed rapidly recently all over the world.Based on the development of ESP in the world, with the need of the 863 project"Research on vehicle global chassis control"and the project"Global Chassis Control's Intelligent Control Mechanism and Key Technology Research with Driver Behavior Simulation"which is supported by Natural Science Foundation of China, research proposed in this paper on the ESP system have began. Based on the"V"mode, our research group and Changan Auto Work overcame all the work in the developing of ESP, including ESP functions definition, dynamics modeling of brake valve and vehicle, control algorithm design and simulation, software-in-loop test and hardware-in-loop test, printed circuit board design, prototype building and road test in summer and winter. Through four years research on the project, a performance evaluation method and a test platform for ESP was completed, the control algorithm designed by ourselves and the corresponding hardware required by ESP system was developed and integrated on the platform of CV8 sedan, and road test have been fulfilled in Honghegu testing field in winter and Hainan testing field in summer. Based on the subjective evaluation and CV8 benchmark vehicle testing data in this 863 GCC program, evaluation method for the matching and improvement of control algorithm is developed in this dissertation:1. In the subjective analysis and evaluation of the driver, we hear the most common complaint is"not feel the system work", especially in the testing fields of the Black River during the winter, this phenomenon is particular in the early shift of obstacle avoidance. And another common complaint is that the brake system ESP intervention interferes the operation of the driver, especially in the driver's operation of counter steer, such active braking or outputting engine torque interfere caused the vehicle can not accurately follow the driver's driving intention, commonly in the continuous curve of the driving conditions. Analyzing from the view of the system reference model intending to characterize the driver driving, the system needs to accurately describe the driver's driving intention in the mathematic view, and can characterize the degree of urgency driving intentions.Based on the driver's steering wheel angular velocity and low-pass filtering properties of the vehicle, we characterize the driver turned on the intent and the degree of urgency , and as a reference model to revise the ESP system, making the ESP system to control timing of intervention is more reasonable, improving the response performance of driver's intention to the vehicle's response, also avoiding the undue intervention of the driver's intention to interfere with normal driving. Finally, we test the validity of the algorithm through the test of a sedan equipped with ESP.2. How to design a set of perfect arbitration mechanism for the ESP control logic is the key problem. The maneuver of driver with the feedback of ESP will make the ESP system switch control state from one to another. The switch scheme should make proper and quick reaction to driver maneuver, avoiding making driver confused by bad switch scheme design. Based on the detailed analysis of the ESP intervention condition and the stability analysis on the vehicle, taking into account the different driving conditions the driver's driving intention of characterization, from the view of improving the control performance, this paper focuses on a detailed design of the ESP yaw control system and the arbitration mechanism of the trigger from the limitation of side slip angle, and also propose a set of systems engineering for the multi-state ESP threshold feedback control algorithm. Finally, through the real vehicle field tests, the performance of the system algorithm is repeatedly verified.3. ESP systematic testing and evaluation of traditional tender method, basically derived from traditional test of the handling and stability, simply considering the vehicles following on the ideal state or reviving the pressure, which are difficult to guide to improve the algorithm ESP system and the post-match. This paper comprehensive research the existing ESP system testing methods, and analysis the driver's driving behavior to avoid accidents. Based on the control algorithm of ESP system setting and typical trigger conditions of system conditions, establishing a more comprehensive evaluation system for the ESP system tests, and making the indicators of the driver freedom to operate 2 / 3 through the obstacle avoidance path, which provides a good benchmark test for the algorithm for the ESP system performance re-inspection and post-match performance evaluation.In addition to completing the technical requirement of 863 GCC program, mathematical representation of driving intention and arbitration mechanism of control method in the ESP sytem were developed in this dissertation. Evaluation index and methodology for the performance test and system matching were designed. The improvement of control algorithm was verified in Hainan and Heihe testing field and satisfactory overall performance was obtained.