Research And Design Of Multichannel Micro-displacement Measurement System Based On LVDT

Precision micro-displacement measuring instruments are widely used in many fields such as industry,agriculture,medical treatment and military.With the development of science and technology,the measurement workload is constantly increasing,the testing tasks are also more and more complicated,and the measurement accuracy is getting higher and higher.However,the traditional micro-displacement also has the problems of single function,few acquisition channels,low acquisition rate,complicated operation and high requirements on the measurement environment.People need a high-precision,wide range of applications,high cost-effective micro-displacement measurement system.First of all,this paper presents a multi-channel micro-displacement measurement system based on LVDT(Linear Variable Differential Transformer),aiming at the disadvantages of the existing micro-displacement testing system.The prototype development and development of differential transformer type LVDT micro-displacement measurement system are completed.One of the hardware design and production of circuits,including microprocessor circuits,power conversion circuits,multiple feedback active band-pass filter circuit,sine wave excitation circuit,balanced drive circuit,instrumentation amplifier circuit,RMS conversion circuit,signal processing circuit,Sensor movement direction identification unit circuit and other parts,and the working principle of each module circuit were analyzed and discussed in detail.Secondly,in order to achieve high-precision micro-displacement measurement,the linear differential transformer LVDT is used as the displacement sensitive element.In order to solve the problems of temperature drift,power consumption and nonlinear correction of linear differential transformer LVDT and traditional analog signal processing circuit,Designed a signal conditioning circuit based on digital signal processing method,using a 16-bit AD sampling chip to convert the displacement voltage.In order to solve the problem that the weak signal is easily affected by the power supply noise,the power supply design scheme is also given.On the basis of the hardware,through the software programming,the micro-displacement measurement with high precision is realized.Finally,this paper also set up an experimental test platform,including data acquisition system platform,signal processing circuit debugging,power debugging,and conducted a series of static tests.These include linearity testing and non-linearity correction,stability testing,and focus on and testing of micro-displacement measurement system prototypes,including forward and return measurements.Relevant test analysis available,the main parameters are as follows: The LVDT micro-displacement measurement system developed by the prototype in the 0～400μm measurement range,can be manually calibrated,calibration points can be arbitrarily selected;The resolution is about 0.1μm,the precision is about 2～3μm,the relative error is less than 3%,the linearity is up to 0.06%,and the time stability is about 0.2μm / h.Meet the design requirements.Finally,the measurement error of the system is also analyzed.