Design And Output Calibration Of Displacement Sensor Testing System For Valves

Valve displacement sensors(LVDT)are essential detection components for high-precision flow and pressure control in valve port independent control systems.In order to achieve real-time and accurate measurement of the displacement of the valve core of a large flow hydraulic valve with independent control of the valve port without disturbing the flow field inside the valve,it is required that the displacement sensor used in the valve must have the characteristics of compact structure,high measurement accuracy,and good vibration resistance.This paper mainly aims at the main performance parameters of the valve displacement sensor(LVDT),builds the automatic test system of the valve displacement sensor,completes the test work of the main performance parameters of the displacement sensor,and uses the particle swarm optimization neural network algorithm to carry out nonlinear correction on the measurement results of the sensor,and designs,processes,tests Calibration has certain significance.Research has been conducted on the performance parameter detection of valve displacement sensors(LVDT)in the following aspects:(1)We have designed a displacement sensor fixture for valves.A combination fixture with a dual guide rod structure was designed,with the sensor body device clamped onto a fixed block of the fixture.The iron core is connected to the moving block of the fixture through a connecting rod,solving the problem of poor coaxiality in traditional fixtures.The entire fixture device has been calibrated and tested with a dial gauge,and its coaxiality error is within ± 0.01 mm.(2)A displacement sensing sensor testing system for valves has been established.The transmission system drives the sensor core to move smoothly,the digital multimeter detects the LVDT output signal,and the high-precision grating ruler collects the core displacement.The user login module was designed using Lab VIEW software;The data acquisition module can control the motion of the calibration device and collect the displacement output of the iron core;The data processing module will fit the collected data using the least squares method to calculate the sensitivity and linearity of LVDT;The printing module can print the detection results.Based on the electrical parameters of the coil and iron core,a signal processing circuit based on AD698 chip was determined,and a transmitter circuit was designed to achieve the conversion between output voltage and output current.An isolation circuit was added to better ensure the stability of the circuit.(3)Performance verification of the testing system.In order to verify the reliability of the testing system,an uncertainty analysis of the entire system was conducted,and the results showed that the stability of the system was 0.0110%,with an uncertainty of less than 0.0126%.In terms of repeatability,the repeatability error of the device is 0.177% within a stroke range of 150 mm.(4)Sensor detection and nonlinear optimization.The performance of the processed LVDT sample was tested,and the experimental results were compared and analyzed with the simulation results.The return error of the sensor was 0.92%.Repeatability testing was performed on the tested sensor for three strokes,with a repeatability error of 0.90% and a zero residual voltage of 0.0026 m V.The nonlinear part of LVDT is optimized by using the BP neural network algorithm of particle swarm optimization,and the linearity of the optimized sensor is improved by 0.01%,indicating that the optimization has a certain beneficial effect on the output performance of the sensor.