Research On Electro-mechanical Braking Actuator And Control Algorithms For Light Vehicles

Electro-mechanical braking system is an efficient and stable automobile braking system with a series of advantages such as faster braking speed,higher braking efficiency and more accurate braking.The control performance of the driving motor is closely related to the working performance of the Electro-mechanical braking system.Therefore,the research on the control performance of the motor is the focus of this paper.Aiming at the problem of dynamic and static coupling of the current loop in the motor motion process,the space vector control algorithm and two control strategies of dynamic decoupling of the current loop are adopted.In order to make full use of the adhesion condition between tire and ground in the whole braking process,and combining the advantages of fuzzy control and sliding mode variable structure control,a fuzzy sliding mode control strategy based on slip rate is designed to track and control the optimal slip rate of wheel.The control strategy can quickly realize the output of target value,disturbance to the outside world and the change of internal parameters.Because of its strong robustness,the control strategy of fuzzy sliding mode braking for vehicles is another focus of this paper.The paper mainly covers the following aspects:(1)Aiming at a target light-duty car,the goal of Electro-mechanical braking system modification for the target vehicle is formulated,the braking force of the target vehicle is checked and calculated,and the actuator of the Electro-mechanical braking system is selected and designed in detail.(2)For the control of EMB drive motor,vector control method is chosen.The realization of vector control algorithm is described in detail.In order to solve the dynamic coupling problem of motor current loop,two current loop decoupling control methods are adopted,which are based on voltage feed-forward decoupling control and complex vector decoupling control.The simulation results show that the complex vector decoupling control can improve the control accuracy and tracking speed of motor current more effectively,thus improving the working characteristics of EMB system.(3)The kinematics model in vehicle braking process and EMB system actuator model are analyzed in detail.The estimation algorithm of optimal slip rate,the optimal distribution algorithm of wheel braking force based on EMB system and the design process of fuzzy sliding mode control strategy based on slip rate are elaborated.Based on the above methods,the vehicle braking simulation model based on EMB is built.(4)In order to verify the effectiveness of the proposed sliding rate-based fuzzy sliding mode control strategy,the EMB-based vehicle braking simulation model is simulated under three typical road conditions and different braking intensity conditions,and compared with the PID and SMC control strategies.The results show that the EMB system based on the control algorithm mentioned in this paper can track and control the optimal slip rate of wheels on various typical roads.By the simulation test under various working conditions,which shows that the EMB system can effectively improve the performance of following control of the optimal slip rate in the braking process under the control of the slip rate-based fuzzy sliding mode control strategy.