Study on Requirements for Load Emulation of the Vehicle With an Electric Braking System

For different configurations of the electric braking systems (EBS) in the vehicle, requirements for the emulation of their dynamic load on the test bench are studied in this paper, in order to determine appropriate parameters of the test equipment. First, models of three kinds of EBS as well as the test bench are built and characteristics of the transmission system including elasticity and backlash nonlinearity with their influences on the braking performance are fully considered. Two normal braking strategies, namely the maximum-motor-torque strategy and the good-pedal-feel strategy, are designed and the antilock braking strategy that includes the regenerative and friction blended torque control of the wheel slip ratio, the sliding mode control of the backlash, and the PID closed-loop control for elasticity compensation in the emergency condition is proposed. With these methods, motor and frictional braking torque are under the coordinated control to make the most of the EBS. Then, the scheme and control methods of load emulation including the PI method and the feedforward method on the test bench are put forward. Based on the models and control methods, vehicle braking results that indicate the emulation effects and requirements of different kinds of EBS in the MATLAB/Simulink environment are shown; and meanwhile, the dynamic performance parameters of the test bench containing the moment of inertia and the time constant of torque response are obtained for the selection of the test equipment. Finally, experiments on the real bench are carried out. The loading and motion of the vehicle EBS under various braking conditions can be accurately emulated on the proposed test bench and the reliable test results make it possible to investigate the EBS safely, economically, and time-efficiently in the laboratory.