Fault-tolerant system for catastrophic faults in AMR sensors

Anisotropic Magnetoresistance angle sensors are widely used in automotive applications considered to be safety-critical applications. Therefore dependability is an important requirement and fault-tolerant strategies must be used to guarantee the correct operation of the sensors even in case of failures. AMR sensors are configured with two Wheatstones bridges where catastrophic (hard) as well as parametric faults can ocurr. Catastrophic faults are mainly related to the conditions of the bridge resistances. If a hard fault occurs at any of the resistances, the sensor must be taken out of operation because the angle can not longer be reliably computed. Previous proposed fault-tolerant systems are based on physical redundancy with hardware duplication, which usually implies higher production cost and can be restricted by the mechanical construction of the sensor. However the proposed fault-tolerant system is based on analytical redundancy to obtain the required voltages to calculate the angle. Results indicate the fault-tolerant system can handle catastrophic fault at any of the bridge resistances, which is especially useful in safety-critical applications. Future research will be focused on parametric faults.