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Improvement of Sensitivity and Noise of a Fluxgate Magnetometer using Modified Firefly Optimization Algorithm

Oluyombo OW, Tekanyi AMS, Sani SM, Jimoh B

Measurements of the magnetic field of the Earth and low frequency magnetic field disturbance require a small size, highly sensitive, low noise, and stable magnetic sensor with directional capabilities. Fluxgate magnetometer design problems usually involve a large number of design variables with multiple objectives under complex nonlinear constraints. The methods for solving fluxgate multi-objective optimization problems can be significantly different from the methods for fluxgate single objective optimization. No matter how simple the problem may be, finding the optimal solution for a nonlinear multi-objective fluxgate optimization problem requires complex numerical effort. Meta-heuristic algorithms start to show their advantages in dealing with nonlinear multi-objective optimization problems. In this paper, the recently developed single-objective Firefly Optimization Algorithm (FOA) was modified to solve fluxgate multi-objective optimization problems. A complete magnetometer based on fluxgate principle for magnetic field measurement has been developed using a ferrite ring core with wire-wound excitation and pick-up coils. The fluxgate magnetometer consists of a fluxgate sensor with electronic circuitry based on second-harmonic detection. The sensing method is based on the conventional type of fluxgate magnetometer with detection of second harmonics by a phase sensitive detector. The sensor realized shows a linear full scale in the range of ±49.44µT with a sensitivity of 97.08mV/μT. In addition, when compared to the existing sensors, the modified FOA sensor exhibited a reduction of the core dimension by 38.9%, the reduction in the pick-up coil winding turns by 66%, increased magnetic field range by 64.8 %, and increased sensitivity by a factor of 8.5.