A Magnetic Sensor Calibration System Based on a Closed-Loop Tri-Axial Field Simulator

Abstract

Magnetism is an omnipresent phenomenon with potential applications in various fields. Immense research has gone into the ways in which magnetism can be used for practical applications. Apart from day-to-day applications such as mobile phones, laptops, railways etc., it finds applications in the aerospace sector as well, for interplanetary studies, navigation, and space robotics. Accurate sensing of the magnetic field is essential for these applications, for which efficient magnetic sensors are used. The precise calibration of these sensors is necessary to quantify various parameters and associated uncertainties to ensure accuracy. For this, a field simulator which can generate a highly accurate and controlled magnetic field is essential. The design and development of a Tri-axis Helmholtz coil field simulator based on Model Reference Adaptive Controller (MRAC) is presented here. It provides a simple, compact, and cost-effective solution for aerospace magnetic sensor calibration. The proposed system offers a uniform magnetic field with 0.1% uniformity within a cubic volume space of 3375cm³. The intensity of the magnetic field can be varied within the full-scale range of 200μT with a resolution of 0.01μT by appropriate current control. The MRAC was finalized after a detailed analysis with various types of controllers such as basic PI, PID and LQI, as it provides precise closed loop control and field stability, which is of paramount importance for aerospace magnetic sensor calibration. It exhibits lesser computational complexity, lower settling time, better adaptability to external field disturbances, lesser overshoot and higher phase margin indicating better closed loop stability compared to other controllers.