Design Of Nano Displacement Sensor's Signal Acquisition And Processing System For PZT Actuator

With the development of modern science and technology, many high technology fields have entered the nano-world, such as processing and manufacturing of aerospace products, precision measurement devices, and high-density integrated circuits and so on. Close to the nanometer scale with the characteristic size of atoms and molecules, the general conventional techniques are no longer applicable, and therefore many countries focused their eyes on the study of nanotechnology, especially in nano-operation and measurement techniques. Piezoelectric ceramic (PZT) driver for its excellent performance is widely used in micro/nano positioning operation fields. However, due to the existence of its own hysteresis, creep and nonlinear shortcomings seriously affect the accuracy of the nano-scale positioning. To solve the above problem, we designed a displacement sensor to measure the real time displacement of PZT and use the close-loop control which based on the feedback of displacement to improve the positioning accuracy of PZT driver.After the three generations improvement, the nano-displacement sensor's accuracy has reached the nanometer level. This paper attempts to improve its signal acquisition and processing system to further improve the sensor's measurement accuracy based on the former work. Through the improvement of the 2nd generation signal acquisition and processing system, we designed and completed the 3rd and 4th generation signal acquisition and processing system which made the displacement sensor's resolution from the original 10nm to current 3nm.In the research background of the National Nature Science Foundation key projects "the robotic operating system theory and implementation in the nano-environment", and the groundwork of force sensor in robot sensor laboratory over years in Hefei Institute of Intelligent Machines of Chinese Academy of Sciences, this paper designed a sensor which can get the real-time PZT driving displacement information using the nano-positioning platform in Shenyang Institute of Automation of Chinese Academy of Sciences.The main contents of this paper are summarized as follows:1. Through the in-depth study of the characteristics of bridge circuit's output signal, we designed and completed the hardware of 3^rd and 4^th generation signal acquisition and processing system. The hardware circuit including bridge circuit,Multi-stage front-end amplifier,anti-aliasing filter circuit,data acquisition circuit and the USB circuit using to communicate with the PC. The results show that the circuit can amplify a weak differential signal at the same time, there is effectively suppress noise in the surrounding environment.2. Design and implementation of interactive interface based on LabVIEW. The software enables real-time display of measured data and the storage, analysis and processing functions. It also allows users to send commands through the PC to achieve the lower computer access and control.3. We respectively built up two sets of test platform which based on displacement and force input. We conducted a comprehensive performance test of nano-displacement sensor using the 3^rd and 4^th generation signal acquisition and processing system, the linearity, lag, repetitive and other characters'curves and analysis results are presented. This paper also analyzes the relationship between force and displacement input curve. Finally, we gave the performance comparison between the 2^nd generation system and the 3^rd and 4^th generation system by experiments. Experimental results show that the research in this paper can really improve the performance of the nano-displacement sensor.