Flux Linkage Sensor Fusion of a Variable Reluctance Differential Solenoid Transducer

This paper presents the application of a novel sensor fusion strategy for a variable reluctance differential solenoid transducer (VRDST). A prior work demonstrated that the VRDST could simultaneously produce slow-speed and high-speed plunger position estimates. This work demonstrates that these position estimates can be fused using a complementary filter to achieve a superior plunger position estimate that is accurate over a wide range of mechanical frequencies. The proposed complementary filter fuses disjoint slow-speed and high-speed flux linkage measurements to produce a wide-bandwidth position estimate. The paper begins by deriving the high-speed flux linkage-based measurement and complementary filter. A Simulink simulation is then used to characterize and contrast the behavior of the inductance-based, flux linkage-based and complementary filter position estimates. The simulated results show the complementary filter is successfully able to reject the erroneous aspects of the prefiltered inputs and therefore produces a more accurate position estimate. A prototype VRDST is then used to demonstrate that the projected improvements seen within the simulated results are realizable with a physical prototype. The findings of this work show the complementary filter output can perform well at high-speeds without producing phase-lag error which is typically seen in linear variable differential transformers (LVDTs) and differential variable reluctance transducers (DVRTs) as their mechanical speed approaches the excitation frequency. Therefore, the VRDST is presented as an inductance-based sensor that can exceed the mechanical bandwidth of LVDTs and DVRTs for a given excitation frequency.