Research On EPS And ESP Coordinated Control And The Key Technology

As development of vehicle dynamics, modern control theory, electronic technology, sensor technology, computer simulation technology and vehicle network technology, the loading rate of vehicle chassis electric control system is higher and higher, which is represented by Electric Power Steering(EPS) system and Electronic Stability Program(ESP), they play an important role in improving the all aspects performance of the vehicle. These systems are mostly focus on improving a single performance index, developed by separate parts manufacturer, and not consider to share the signals with other electronic control system and coordination etc problems. The simple function superposition often leads to conflicts between the subsystems, the vehicle can not achieve the optimal performance, so the integrated and coordinated chassis control is one of the hot spot research in recent years. Chassis coordinated control shares signals between each system, avoid conflicts and interference between them, according to the change of driving conditions and the vehicle states etc, full play the specialty of the subsystems, achieve the optimal vehicle comprehensive performance.This dissertation is based on the national natural science fund project (51175135, 51075112,51375131) and the China aviation industry production special project (CXY2010HFGD26), on the basis of summarizing the latest research results at home and abroad, focus on the EPS/ESP control and the key technology, a series of theory modeling, simulation calculation and test validation research are carried out. The main research work of this dissertation and achievements are summarized as follows:(1) Considering the wrong operation torque caused by the unskilled drivers due to lack of perception of the lateral force, propose a vehicle EPS control strategy of tracking the desired driving characteristics. Establish the driver model which can characterize the driving characteristics (proficiency, etc.) and considering the wrong operation torque, and compose with vehicle to driver-vehicle closed-loop system. Simulation and hardware in the loop test results show that the vehicle EPS control strategy of tracking the desired driving characteristics, improves the vehicle handling stability, reduces the driver’s steering efforts, so as to verify the effectiveness of the proposed control strategy.(2) For traditional return control easily lead to return overdone or inadequate, an EPS return control strategy based on ESP function compensation is proposed. Four-wheel vehicle dynamics model is established, based on vehicle ESP system sensor signals, Unscented Kalman Filter (UKF) method for estimating road friction coefficients and vehicle sideslip angle online real-time is used. The deviation of the estimated sideslip angle and the desired sideslip angle are inputs, sliding mode control is used for vehicle return control. Simulation and hardware-in-the-loop test of the vehicle return ability performance are based on Carsim, Matlab/Simulink and Lab VIEW under different conditions, simulation and test results show that the proposed steering return control strategy based on ESP function compensation can improve the on center handling performance and better returnability is achieved.(3) EPS and ESP play an important role for ensuring the vehicle good handling stability and driving safety, the necessity of the coordinated control of vehicle EPS/ESP system and the coupling characteristics of vehicle longitudinal and lateral dynamics are described in detail in this dissertation. For the coupling factors exist on the vehicles’ longitudinal and lateral dynamics control, there may be conflicts between the two systems under some conditions, propose an EPS and ESP coordinated control strategy based on vehicle driving safe boundary. Establish EPS dynamics model, aligning torque is estimated by Luenberger observer, road adhesion coefficient is estimated from the aligning torque information. Vehicle driving safe boundaries consisting of sideslip angle and yaw rate is determined by the vehicle dynamics, according to the established safe boundary and steering wheel torque, yaw rate etc. information, optimize EPS and ESP dynamic coordinated control factor based on elite non-dominated sorting genetic algorithm, guarantee obtain the global optimal solution of the optimization parameters. The simulation and test results show, the EPS and ESP coordinated control strategy based on vehicle driving safe boundary, improve the driving stability of the vehicle, thus verify the effectiveness of the control strategy.(4) The EPS controller, ESP controller and upper coordinate controller are designed, the hardware in the loop test and the real vehicle tests are done under different working conditions, which prove the correctness and the effectiveness of the proposed control strategy.