Design and Validation of a Variable Reluctance Differential Solenoid Transducer With an Ironless Stator

This article presents the design methodology, simulation results, and experimental results of a novel variable reluctance differential solenoid transducer (VRDST). The new ironless-stator VRDST (ISVRDST) is designed to mitigate the practical challenges inherent in the VRDST while maintaining its beneficial features compared to other linear inductive differential position sensors. The ISVRDST uses an air stator to reduce cost and increase compactness. FEA and Simulink simulations are used to predict the performance of the ISVRDST and a proof-of-concept prototype is designed to experimentally validate the simulation results. Like the VRDST, the ISVRDST is designed to utilize a complementary filter to fuse a low-speed position measurement with a high-speed velocity measurement, resulting in a single wide-bandwidth position measurement. The experimental results of the prototype ISVRDST prove that it is capable of robustly performing and fusing the two measurements utilized by the VRDST. In addition, the analytically predicted error of the fused measurement is found to be less than 1% different than the actual error relative to a high-precision laser vibrometer. When compared to the VRDST, the ISVRDST prototype is found to have a stroke-to-length ratio that is nearly four times greater and a cost that is over 100 times lower.