Sensor Systems for PHM

This chapter introduces the fundamentals of sensors and their sensing principles. It discusses the key attributes of sensor systems for prognostics and health management (PHM) implementation. The chapter describes some state‐of‐the‐art of PHM sensor systems. It presents the emerging trends in sensor system technologies. From the point of view of sensing principles, sensors are classified into three major groups: physical, chemical, and biological. The physical principles or effects involved in detecting a measurand include thermal, electrical,mechanical, chemical, biological, optical, and magnetic. A PHM sensor system will typically have internal or external sensors, internal or external power, a microprocessor with analog‐to‐digital (A/D) converters,memory, and data transmission. Sensor systems can be divided into two main categories with respect to their power sources: non‐battery‐powered sensor systems and battery‐powered sensor systems. Onboard memory is the memory contained within the sensor system. Memory management allows one to configure, allocate, monitor, and optimize the utilization of memory.