Research on Displacement Measurement and Self-detecting Circuit Based on LVDT

Abstract

A Liner Variable Differential Transformer (LVDT) measuring system and self-detecting circuit are proposed for micro-displacement measurement, which can detect the displacement of LVDT and monitor the fault signals simultaneously. The circuit is composed of a focusing mechanism, a displacement measurement module, a correction module, a monitoring module, an AD conversion module, a drive module, a control module and a power conversion module. Due to the requirements of high reliability and long life of space remote sensing system, as well as the radiation influence in space, LVDT measurement and control data need to be monitored and validated. The displacement signal output of LVDT is an important signal quantity for fault detection and closed-loop control of the system. By analysing the displacement signal and drive output signal of LVDT, fault modes such as mechanism stuck-up and mechanism disconnection are detected. Aiming at the limitation of current detection methods, this paper proposes a method of detecting LVDT signal. Circuit protection is added to the circuit to improve the reliability of the circuit. The linearity and fault detection ability of the circuit are tested and analysed.