Research On Anti-lock Brake System For Light Vehicle With Eletromechanical Brake System

As one branch of brake-by-wire, Electromechanical Brake (EMB) introduces a particular conception to Brake System,compared with the traditional brake sysytem. EMB uses electricity as the energy of brake sysytem,drives a set of actuator to provide clamp force with an electromotor.As a result, EMB works qucikly, which improves the active safety.EMB makes use of electromotor instead of the traditional oil pump,and wires in place of oil pipes, Which not only avoids the pollution ofthe environment due to the leakage of oil,but also reduces the laying room, predigests the brake system,and reduces the weight of the vehcile, in accord with the developing requirements such as energy abatement,satfty and the rotection of environment.In this paper,making full use of domestic and international study results based on EMB,with the help of current resoures of our research team,we choose a suitable theoretical model of the clamp force estimation,complete the study of the clamp force estimation of an EMB actuator,design an EMB controller without a clamp force sensor, finish the off-line simulation test and verify the reliability of the controller with HIL(hardware-in-loop) tests;based on the model of EMB,we construct a study of the ABS control algorithm and some off-line simulations with the simulation software.We instruct some test research under typical conditions in the HIL platform and validate its accuracy.1 Research on Estimation of Clamp Force of EMB ActuatorA suitable theoretical basis is chosen for the estimation of clamp force.Based on CANOE,a clamp force estimation test-bed is developed.After estimation tests,we caculate the relationship between clamp force and motor current or rotor running angle,acquire a clamp force estimation model,create an EMB controller without a force sensor.And we validate the reliability ,according to the off-line simulations and HIL tests.2 Research on Anti-Lock Brake Control Algorithm Based on EMB An algorithm was developed with slip ratio as target variables for control.The slip ratio was calculated according to the vehicle speed and the wheel speed,the former being directly measured and the latter being estimated.What is more,in view of the nonlinear property of ABS and disadvantages of the traditional PID control,the fuzzy algorithm is combined with the PID control.Therefore,we chose the fuzzy–PID algorithm to calculate the target brake force and calculated the parameters of the PID conteoller based on the fuzzy algorithm.So that,the PID controller can work out the most suitable target brake force.3 Simulation on the ABS Control Algorithm Based on EMBAccording to the brake force estimation of EMB,a simulation model of the ABS control of total vehicle was developed.The simulation model consists of vehicle model,wheel dynamics model,engine model,powertrain model,tire model,assistant module,EMB model;the off-line simulations of the ABS control of the total vehicle was constructed under different conditions such as avarage road,combined raod,divided road and chessboard road during linear brakingin addtion to swerve.The results shows that the ABS control algorithm can effectively confine the wheel slip ratio to a certain range,evidently enhancing the brake performance.The algorithm can adjust brake force at once on jump-μroad;it can also provide a great handling performance for the vehile on split-μroad.