Design, Modeling, and Experimental Verification of a Hall-Effect-Based Linear Instrumentation System for Through-Shaft Angle Sensing

This article presents a simple instrumentation system for sensing the angular position of a through shaft. The system, broadly, consists of two parts: 1) a Hall-effect-based sensor module (SM) consisting of a twin eccentric-disc rotating arrangement and 2) a linearizing digital converter (LDC), which acts as an efficient interface for the transducer part. The SM provides cubic-natured push-pull outputs with respect to the angle. The linearizer further accepts these signals, performs a voltage-to-frequency transformation, and then applies novel linearization function to render a linear direct-digital indication of the angle. The article discusses the design and theoretical modeling of the SM, and its characteristics are derived. The sensor characteristics observed from simulation are in agreement with theoretical studies. Simulations are also extended to study the effect of important mechanical/magnetic parameters of the SM. Optimal parameter values are also inferred from these studies. The LDC and associated methodologies are also studied and presented in the article. The performance of the instrumentation system is validated using a hardware model of the SM and a prototype of the LDC. The experimental results show that the sensor and linearizer work as expected. Interfacing tests show that the overall instrumentation system gives an accuracy of less than 0.4% and a resolution of 0.2° over a wide range.