A Novel Signal-Mapping Based LVDT Signal Conditioner

We propose a novel displacement measurement method in the LVDT (Linear Variable Differential Transformer) structure. This proposed algorithm is independent of coil pattern, which may be implemented to PCB, or transformer component, because it is based on the signal-mapping method. That is, the proposed algorithm uses not absolute measurement value but relative value. The LVDT structure consists of dual transformers or coils; in this case, it is very difficult to have exact duality for these coil pattern on a PCB or two transformer components. In practice, therefore, several tuning processes required are carried out. Whereas, proposed signal-mapping based algorithm needs just once calibration process at the final stage in manufacturing process. The proposed algorithm can easily change the sensing accuracy, operation region, output value region, and so on. And also the proposed algorithm can transform the non-linear characteristics of input signal to the linear in the calibration operation. To verify our signal-mapping based algorithm, we have manufactured several boards which have different coil patterns and our algorithm is ported into TMS320F2812 of TI DSP chipset. The output signal has high accuracy and high stability although PCB coil pattern are coarse.