Design and Analysis of a Mutual Inductance Coupling-Based Microdeformation Sensor

Abstract

Mutual inductance coupling-based electromagnetic sensors utilize the quasi-static or dynamic magnetic excitation and sensing signals to detect the multiaxis deformation. The compact size and high sensitivity allow their application in tiny and precise measurement systems, such as space-confined minimally invasive surgery. Until now, however, there has not been any theoretical derivation of the relationship between microdeformation and obtained electromagnetic signals yet. To address this problem, this paper presents a triaxial deformation sensor with corresponding measurement electronics based on lock-in technique to pick up the sensing signals for deformation reconstruction. Simulations and experiments were carried out to explore the relationship between mutual inductance and triaxial deformation, including longitudinal compression from 3 to 4.8 mm, inclination angle from −20° to 20 °, and orientation angle from 0 ° to 360 °. The results indicate that the orientation angle $\beta $ can be expressed in terms of arctan function of the mutual inductance and longitudinal compression $\rho $ can be achieved through polynomial fitting method. The inclination angle $\alpha $ shows a linearity with the mutual inductance components along $\alpha $ direction when $\rho $ is fixed, and the linear coefficient changes with $\rho $ . Finally, the deformation was reconstructed with the average errors of 0.00037 mm, 0.9199 °, and 0.000026 ° and the corresponding root-mean-square errors of 0.0144 mm, 1.3608 °, and 0.1356 ° for $\rho $ , $\beta $ , and $\alpha $ , respectively. The reconstruction algorithms and measurement circuit will promote the application of microtriaxial deformation sensors in high precision displacement measurement and multiaxis force sensing systems.