Fuzzy sliding mode control based on longitudinal force estimation for electro-mechanical braking systems using BLDC motor

This paper focuses on the controller design using fuzzy sliding mode control (FSMC) with application to electro-mechanical brake (EMB) systems using BLDC Motor. The EMB controller transmits the control signal to the motor driver to rotate the motor. The torque distribution of motors is studied in this paper actually. Firstly, the model of the EMB system is established. Then the state observer is developed to estimate the vehicle states including the vehicle velocity and longitudinal force. Due to the fact that the EMB system is nonlinear and uncertain, a FSMC strategy based on wheel slip ratio is proposed, where both the normal and emergency braking conditions are taken into account. The equivalent control law of sliding mode controller is designed on the basis of the variation of the front axle and rear axle load during the brake process, while the switching control law is adjusted by the fuzzy corrector. The simulation results illustrate that the FSMC strategy has the superior performance, better adaptability to various types of roads, and shorter braking distance, as compared to PID control and traditional sliding mode control technologies. Finally, the hardware-in-loop (NIL) experimental results have exemplified the validation of the developed methodology.