| Electromechanical Brake (EMB) is a kind of new-style brake system. Response time and drive efficiency of EMB are better than hydraulic brake system, because EMB adopted electromechanical transmission instead of hydraulic transmission.Therefore, EMB is considered the major method to improve braking performence. However, braking performance and handling performance of vehicle can not be optimized only with EMB, other control systems have to be integrated. Vehicle Stability Control (VSC) is the third generation of vehicle stability control system, it can improve the vehicle braking performance, driving performance and handling performance by means of controlling braking force. So the research of EMB and the VSC based on EMB has become increasingly concerned about in vehicle brake system. In the dissertation, the research on EMB and the VSC based on EMB has been done based on projects"Simulation platform for software-in-the-loop of electromechanical brake system of car","Study on ABS/ASR/ESP based on electromechanical brake system of car","Research of vehicle dynamic control based on brake-by-wire"and"Research on vehicle intelligent brake system".Firstly, the plan of redesigning brake system and the design objective of EMB actuator were made. Four EMB actuators were developed according to the plan and design flowchart. The design method of electronic brake pedal was given and the electronic pedal for target vehicle was designed. Afterwards, the software and hardware's schemes for EMB controller were given, and the hardware and control procedure are set up base on the scheme. The off-line simulation and bench test were carried out to adjust the parameters of EMB control system and the performance of EMB system is verified. Secondly, based on the performance of EMB, the research on algorithm of ECU for VSC was developed. Finally, the structures of off-line simulation platform and hardware-in-the-loop test bench were built based on Matlab/Simulink/xPC Target platform. Some different situation tests were carried out on the simulation platform and HIL test bench.1.Design of the hardware for EMB systemAccording to the requirement of projects, the brake system of vehicle was redesign. The design specification for EMB actuator was given according to the production hydraulic brake system and this was the design bases of EMB actuator. After the flow chart for EMB actuator design and parts selection were given, three transmission schemes for EMB actuator and the corresponding theory designs were made. Through comparison, the third scheme was adopted and four EMB actuators were made. After the scheme for electronic brake pedal was given, the flow chart of electronic brake pedal was decided. According to the characteristic of target vehicle, the electronic brake pedal was developed independently and the test was performed. The test results showed the electronic brake pedal could satisfy the requirements.2.Design of the control system for EMBBased on the blue print of EMB actuator, the design method of control system for EMB and the design of software and hardware were completed. The hardware design consists of design of single chip minimum system, wiring design of signal interface, wiring design of communication, design of drive circuit for motor. The design of signal interface consists of wiring design of interface for analog signals and wiring design of interface for digital signals. According to the requirement for EMB performance, the software adopted the control structure of three loops and the flow chart of the program was given. The designed software consists of the module of initialization, the module of motor commutation, the module of three loop controls, the module of armature voltage control and the module of tachometry.3.Research on control characteristic of EMBAccording to the need of future research, the off-line simulation and bench test were combined to adjust the parameters of EMB control system and verify the performance of EMB system. The parameters for EMB model were obtained through the attribute testing of EMB actuator. The simulation model of EMB was built and the control parameters of three loop controller for EMB were obtained through off-line simulation. The building of EMB simulation model established the foundation for the off-line platform. Based on the results of off-line simulation, the control parameters which were applicable to EMB controller were obtained through bench test. The test results showed: the EMB model and EMB system are good and they could satisfy the need of use. The results proved the way for the off-line simulation and HIL test.4. Research on VSC based on EMBWhen the performance of EMB can meet the challenge, the research on algorithm of VSC based on EMB and ECU of VSC was performed. First, the main flow chart of VSC control algorithm was given. The VSC control algorithm consist module of wheel speed computation, module of vehicle state estimation, module of anti-lock brake, module of anti-slip regulation and module of yaw stability control system. The module of vehicle state estimation consists of module of vehicle velocity estimation, module of nominal yaw rate estimation, module of road adhesion coefficient estimation and module of wheel load estimation. Based on VSC control algorithm, the hardware configuration of VSC controller was given and the design of hardware was given. The hardware design consists of chip selection, wiring design of clock , wiring design of reset, wiring design of power supply, wiring design of interface for analog signals , wiring design of interface for digital signals, wiring design of CAN and wiring design of analog output mainly.5.The building of VSC simulation platform base on EMB and the research of off-line simulationAccording to the need for VSC control algorithm based on EMB, The VSC simulation platform was built. This platform consist of 15DOF vehicle dynamics model, graphical user interface, 3-D virtual scene, and the vehicle model consists of engine model, powertrain model, EMB model, tire model, wheel dynamics model, suspension model, vehicle body model and driver model.VSC simulation on various conditions was proceeded on the platform condition. The results showed: at braking the slippage of vehicle wheel could be controlled to follow the target and the the directional stability of vehicle was improved. At driving condition, over-slip of driven wheels which were on low-μroad was avoided effectively using braking control, and the capability of startup of the vehicle was improved obviously. When steering, the yaw rate and slip angle were controlled to target through brake force regulation, thus the lateral stability of automotive was improved, efficiently.The building of off-line simulation platform and the off-line simulations established theory foundation for the design and development of HIL test platform and HIL test.6.The research of VSC HIL test platform based on EMB building and HIL test According to the need of research for VSC based on EMB, the plan of test platform was given and the HIL test platform was built based on Matlab/xPC Target. The platform consisted of one host computer, two target computers, four suits of EMB actuators, four suits of EMB controllers, VSC controller, sensors, signal collecting system, VF and software system. Some VSC HIL tests on various conditions were proceeded and the platform based on control algorithm prototype. The test results showed: The EMB can satisfy the requirement of VSC. At braking condition, wheels lockup was avoided effectively with shorter stop distance. When driving, over-slip of driven wheel which is on low-μroad was avoided effectively using braking control, and the capability of vehicle acceleration was improved obviously. When steering, the oversteering or understeering of vehicle could be restrained effectively through brake force regulation, thus the lateral stability of automotive was improved. In summary, the VSC HIL platform was qualified to the test.
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