A flexible high-precision capacitive displacement sensor

Abstract In flexible conveyor systems and measurement systems where linear and angular displacements are used in combination, the use of multiple linear and angular displacement sensors for displacement measurement increases the complexity of the system and poses a great challenge to system design and accurate positioning. In this paper, a flexible high-precision capacitive displacement sensor is proposed, which can be applied to both linear and angular displacement measurements. The sensor consists of a dynamic ruler with excitation electrodes and a fixed ruler with sensing electrodes. The excitation and sensing electrodes are printed on an insulated flexible substrate using a flexible printed circuit process. This design provides good ductility, small size, and excellent electrical performance. It enables the conversion between straight-line and cylindrical forms for linear and angular displacement measurement. In this paper, the mathematical measurement model and electric field simulation model of two different measurement forms of the sensor are established, and the measurement performance of the sensor in linear and cylindrical forms is verified through experiments. The results show that the measurement error is ±6μm in the linear displacement measurement range of 0∼312mm and ±17.5″ in the angular displacement measurement range of 0∼360°. With the characteristics of flexible and extensible, small volume and thin thickness, the sensor proposes a new application technology for the complex problem of using multiple sensors for positioning and measuring in the combined path positioning measurement of high-precision and complex conveyor systems.