Study On Inductive Displacement Sensor Applied In Focusing System

Focusing system is an essential part of large-scale photoelectric tracking telescope system, the systematic performance of the whole tracking system is directly determined by the focusing accuracy. Beyond accuracy, the factors such as the equipment working environment and volume also should be considered. Therefore, research on micro-foucusing system which has widely temperature adaptability in valuble. At present,there are two main types of focusing techniques applied in photoelectric tracking telescope system,one is based on laser triangulation methods,and the other in based on image cost function. Both methods needs displacement transducer. But now, most focusing mechanisms adopt grating ruler as feedback to realize closed loop control system. However, those schemes have many shortages such as bulky size and poor temperature adaptability which can not meet the requirement of high temperature working environment. This article proposes to find a displacement sensor which has high detection precision as while as wide temperature adaptability.The paper starts by introducing the present research state and future development tendency of displacement transducer, then summaries the advantages and disadvantages of different kinds of displacement sensors. By comparison, the article get a conclusion that inductive displacement has simple structure, good linearity and high cost performance. Inductive displacement sensor using the electromagnetic induction principle to change physical quantities into electrical signal,which has fast dynamic response speed and high detection precision. Since then,this article choose inductive displacement transducer as research object.Sencondly,this article briefly introduce the classification and their measuring principle of the inductive displacement sensor. Then through analyzing the requirement to displacement sensor by photoelectric tracking system,the article finally determines the type of inductive displacement transducer. After that,according to characteristics of inductive displacement sensor and its noise sources,the paper compares different de-noising methods and the analyzing the main performance parameters of this sensor.Finally,the hardware experimental platform based on DSP&FPGA is built to prove the feasibility of applying the inductive displacement to photoelectric tracking system. In this part, the paper introduces the selection and function of each component in the platform in detail. The platform contains a DSP & FPGA focusing controller, a stepper motor, and an electric displacement. The designs involving hardware implementation and software simulation are also detailed. Systematic parameters analyzing and experimental results indicate that this design can satisfy the expected requirements.