Research in fuzzy diagnostics of brake-by-wire systems focuses on the power electronics switches, since they are often considered to be the weakest link in the system. The objective of fault diagnostics in the power electronics of the brake-by-wire system is to accurately locate any faults within the circuit as soon as they occur.

The system architecture of a fully Electromechanical Brake-by-Wire System. The thick lines represent the power lines from the battery; the signal lines are shown as thin lines.

The figure illustrates the system architecture of a fully electromechanical brake-by-wire system. In this system, the battery is connected to the actuator motors and power electronics through wirings. The motor is a brushed DC motor, which is inexpensive and is available in the automotive industry abundantly, and which can be permanent-magnet-based or have a field winding. The system has four actuator motors corresponding to each wheel and located in the vicinity of the brakes. The thick lines in the figure represent the power lines from the battery. The signal lines are shown in thin lines. The position signal from the brake pedal goes to a controller, which generates control signals to activate each of the motors. Although a single thin line is shown running from the controller to the power electronic blocks, in reality, they are separate. This can help all four actuators run independently, is more robust during a failure of any one or more of the actuators, and can lead to better graceful degradation during a failure mode.

A reference voltage is obtained, which is fed to the motor terminals. This voltage is obtained from the DC battery by a mean of PWM (pulse width modulation) techniques, which allows synthesizing the desired V* based on the pulsed voltage initiated by the switches. This system model is implemented in BBW-SIM, a simulated model generated using MATLAB-Simulink.

This work was done by Yi L. Murphy and Abul Masrur of the University of Michigan- Dearborn, and ZhiHang Chen and BaiFang Zhang of the U.S. Army RDECOMTARDEC.

ARL-0049


This Brief includes a Technical Support Package (TSP).
Fuzzy System for Fault Diagnostics in Power Electronics-Based Brake-by-Wire System

(reference ARL-0049) is currently available for download from the TSP library.

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