Study on the viability of a microminiature inductive angular position sensor using low-cost fabrication techniques

In this study, we propose an inductive angular position sensor comprising thin film, gold spiral inductors on ceramic chips as an alternative to the current state of the art which suffers from limitations in terms of the scope for micro-miniaturization. The geometry of the transmitter and receiver coils, operating frequency, and the air gap between the transmitter and sense coils all influence the performance of the sensor. Herein, we design and fabricate an inductive position sensor based on micro inductors normally employed in the resonant elements of microwave circuits and as chokes in power sources. We use these inductors as both a magnetic field receiver and transmitter and quantify the generated electromagnetic field. This approach has the advantage of providing angular sensing while being substantially easier and more economical to fabricate compared to currently available commercial sensors. The sensor is designed in such a way that the inductance versus angular displacement possesses an arctangent relationship. Due to this feature, the angular position is obtained easily from the sensor signal without the need for complex mathematical calculations, which is not the case for most of the planar coil-based sensors. A prototype of the proposed sensor has been developed and tested. The sensor has an accuracy comparable with much larger existing sensors (residual error standard deviation 2.55% of full scale), a high linearity (R-2 99.3%) and a low sensitivity to injected noise (0.5%). This low-cost, miniature, rotary position sensor could find numerous applications especially in the modern field of automotive engineering.