Study On 2D Wide-range, High-precision Displacement Measuring Method And System Based On Planar Capacitive Sensor With Direct Decoupling Effect

With the developments of the science & technology, the ultra precise measurement technology has been widely developed, in the direction of high-precision, wide-range and measuring multi-dimensional displacement simutaneousely. Currently, one-dimensional linear displacement measurement has been able to achieve above mm-order stroke with nano-order resolution, but it needs one measuring devices for each dimension and leads to Abbe error when multi-dimensional measurement required. With the increasing demands of simutaneouse multi-dimensional displacement measurement, there is great significance in researching on multi-dimensional measuring system, which has many merits: low cost, good performance, high-precision, wide-range, and so on. This thesis carries on related researches and develops the multi-dimensional displacement measuring system with the self-designed planar capacitance sensor.On the base of the basic principles of detecting displacement by capacitance sensor, this paper designed a planar capacitance sensor which can achieves two-dimensional displacement with direct decoupling. Based on this sensor, a wide range, high-precision, two-dimensional displacement measurement method that can realizes directly decoupling has been presented. Researched and developed the two-dimensional displacement measurement prototype system that can realizes directly decoupling.The main contents of this thesis are as follows:The first chapter recalls the development status and trend of the ultra-precise displacement detection technology both at home and abroad. With the developments of the modern science & technology, introduces these new requirements for the ultra-precise detection technology. Analyzes the existed problems and then raises the purpose and importance of the research. Finally the main context of this thesis has been released.The second chapter firstly introduces the basic principle of detecting displacement by capacitive sensor. Then a wide range, high-precision, two-dimensional displacement measurement method that can realizes directly decoupling has been presented. Based on this, designes structure of the planar capacitance sensor that can realize directly decoupling measurement, and extends its functions.ChapterⅢproposes several options for capacitivity and corresponding sensitivity menthods, and do the mutual comparison between these methods, then show their results. Optimizes and designes all of the relevant structural parameters which impact the performance of the sensor.ChapterⅣintroduces hardware development of the two-dimensional displacement measurement system that bases on the planar capacitance sensor. Has focused on analyzing the signal take-off and condition hardware circuit of the planar capacitive sensor. Then introduces common capacitance signal detection technology. Followed by the characteristics of planar capacitance sensor, design the hardware circuits include signal detection, demodulation, filtering module, and so on. Additionally, proposes and implementes many effective anti-interference measures.ChapterⅤintroduces the signal processing algorithm and software development of the two-dimensional displacement measurement system. Researches on the various software modules and the overall programme to achieve the displacement information. Designes and implementes the test programme which based on the LabVIEW and the data acquisition card, also proposes a real-time processing programme based on DSP that can integrate with control system conveniently.ChapterⅥtestes and validates the system's performance, also analyzes the experimental results. The relevant experiments are followed behind,A comprehensive conclusion and will be presented in ChapterⅥ.