Research On Electromechanical Brake Control System

In the current development of automobile industry, the electronic mechanical braking (EMB) technology will gradually replace the traditional hydraulic braking system due to its fast response, small size and light weight. At the same time, the anti-lock braking system (ABS), which has been an integral part of auto, in improving the braking safety has a role that can not be ignored.In this thesis, with the financial support from the Province Natural Science Fund Project:electric vehicle brake-by-wire system key technology research (No.LY13E050003), a set of integrated ABS electronic and mechanical braking control system was designed. This system, under the premise of the compression cost as much as possible, can meet specified in national standard GB7258-2012 braking performance indicators, and realize the electronic mechanical brake gap adjustment. The main research contents are as follows:(1) The design and production cost of the control system was analyzed. The hardware of the sensor, the complexity of the control algorithm and the realization of the software were used as the direction of the production cost control in the system design process. A framework of EMB control system integrated with ABS was established, which was divided into modules. The function of each module was developed. The vehicle dynamics model related to control system was established.(2) Considering the braking comfort of occupants, the brake pedal displacement, pedal speed and car speed were chose as the braking intention recognition parameters. The linear output relationship between brake pedal displacement and braking force was established. Also, based on pedal speed and auto speed, a query table was established to determine the brake pedal displacement-braking force linear scaling factor.(3) Two critical points which are created in the braking process are recognized by the change of the current signal. And the motor current is used to estimate the size of the braking force. A control strategy of the gap adjustment of EMB device was proposed, which solved the problem of increasing the installation space and cost of additional sensors or auxiliary machinery.(4) By analyzing the existing ABS control method, the ABS control structure framework was established, based on the continuous control of slip ratio error. According to the ABS control structure frame and the EMB control system, the simulation model was established. The braking distance of different road under the control of ABS/no was compared. The simulation results shown that the braking system can meet the requirements of brake performance index of GB7258-2012 under the control of ABS.(5) The feasibility of the EMB control system with integrated ABS function was tested in practical vehicle.