Modelling and simulation of an inductive displacement sensor for mechatronic systems

The paper presents design, simulation, implementation and testing of an inductive displacement sensor based on a Linear Variable Differential Transformer (LVDT) controlled by a single chip electronic module with 16 bit RISC microcontroller. LVDT device is widely used in hydraulic and pneumatic mechatronic systems for measuring physical quantities like displacement, force or pressure; it consists of two magnetic coupled coils with a common moving core; its displacement is converted in reluctance variation of magnetic circuit. Standard electronics for LVDT sensor conditioning is analog - quadrate oscillator, synchronous demodulator and amplifiers - but has its drawbacks - relative complex, hard to adjust, many components and packages, no connection to computer systems. The originality aspects of the work come from the unique method of finding displacement information by switching supply voltage in the coils of inductive device. This method uses only peripherals from a microcontroller so is low cost and easy to adjust. Present paper focuses on modelling and simulation of displacement measuring method but analyzes also implementation aspects for a real application (an electro hydraulic position control system).