An integrated design approach for self-validating fault tolerant smart sensors

Microsystems used for safety critical applications require robust architectures to achieve satisfactory levels of reliability. The Integrated Diagnostic Reconfiguration (IDR) approach described may be adopted to produce a design that provides online diagnostic isolation and fault tolerance by continually reconfiguring analogue components within the device. Characteristic signal fluctuations are observed in the presence of a fault and these may be analysed to provide detection and identification of the faulty component. Once the fault has been isolated it is then possible to select the output from configurations that exclude the faulty component, potentially giving a useful result in the presence of component failure. The IDR concept is described using a Wheatstone bridge sensor interface circuit as an example. Laboratory results obtained from a working demonstrator are used to show how a fault may be accommodated in real time