Design Of The LVDT Displacement Measurement Sensor Circuit And Study On Nonlinear Correction

As a precise displacement measurement sensor,LVDT(Linear Variable Differential Transformer),with many advantages such as long durability,high resolution,strong adaptability to various environments,etc.,is irreplaceable.And its widely used in industrial production,health care,teaching and research,national defense and military fields,which also shows that the value of LVDT displacement sensor is very large.In this paper,the basic theory of LVDT displacement sensor is elucidated,and its equivalent circuit is deduced and analyzed.The frequency-adjustable sine wave generating circuit based on AD9833 is designed to provide sine wave excitation signal for LVDT and provide reference signal for phase-sensitive detection circuit.Through the front signal processing circuit,LVDT output signal filter the noise in the signal.The modulation and demodulation circuit,designed according to the principle of locking amplification,provides modulation and demodulation for signal output of the LVDT displacement sensor and converts the AC sinusoidal signal into a DC voltage signal,then,In the form of DC voltage through the digital multimeter for display.The nonlinear part of its output is corrected by BP neural network,and the Artificial Bee Colony algorithm is used to optimize the neural network.The construction and debugging of the hardware circuit design is completed through the Multisim 12 simulation platform.The use of simulation platform for the first system circuit simulation debugging is able to avoid the repeated production of circuit board for debugging,which not only meet the design requirements,but also greatly reduced the design and development cycle and cost of the product.Since simulation debugging is completed,the circuit using PADS to draw PCB circuit board,completes the weld of the components in the measurement system circuit PCB circuit board and verifies through the experiment.The nonlinear correction part is simulated by MATLAB software.Finally,the displacement measurement system is completed and the experimentis carried out.The data collected by the experiment are analyzed.The error of the LVDT displacement measurement system is about 0.04 mm.At the same time,the relations between input and output of LVDT are linearly,which shift to non-linearity at the end of zero and at the end of the range.The neural network and ABC-BP neural network optimized by genetic algorithm is used to correct the nonlinear part,so as to extend the range of the measurement system.