Fault-Tolerant Control of EMB Systems

In this paper, for the fault-tolerant control of electro-mechanical brakes (EMBs), we continuously estimate several system variables and utilize these estimates to detect faulty sensor outputs. The clamping force is estimated by using the motor position and hysteresis phenomenon during clamping and releasing. Current sensor faults can be easily derived from the characteristics of a three-phase balanced circuit, and the motor position is estimated by applying different methods in low-speed and high-speed regions where a model-based approach is adopted. Using the proposed fault-tolerant logic, we can detect which sensor has a fault during driving or braking. Then, we use a bumpless transfer technique so that the control performance does not deteriorate when the estimated values are substituted for the measured values. The validity and the effectiveness of the proposed fault-tolerant control for an EMB are shown by using EMB hardware-in-the-loop simulations (HILS), so that fault tolerance is guaranteed for a scenario of sensor failures. The HILS consists of an EMB set, a TriCore-based actuator Electronic Control Unit (ECU), a host PC, and a CAN monitoring tool.