Nanometer resolution dynamic displacement measurement in industrial/high noise environments

This paper demonstrates the suitability of giant magnetoresistance (GMR) sensors for very high resolution positioning applications. GMR sensors have several advantages over existing sensing schemes, such as low cost, small form factor and simplicity. However, most applications of GMR sensors, so far, have been limited to RPM measurement, hard disk heads and magnetic probes, and where it has been used for positioning, details on signal and sensor conditioning are not given. We present details on the circuitry, its requirements to be able to achieve the desired resolution, the implementation challenges and their solutions. The sensor is characterized for various configurations, both in static and dynamic operation. We show its suitability even for high bandwidth applications, and its versatility in adapting to various range and resolution requirements.