Design Of High-precision Displacement Senor Based On Magnetic Grid

Displacement sensor is one of the most important sensor in the modern scientific research and industrial production.It is widely used in various fields,such as high precision CNC machine tools,aerospace,petrochemical and other significant fields of national economy.To meet the increasing demand of modern industrial production,displacement measurement is developed towards higher precision,digitalization,anti-interference and intellectualization.Based on these requirements,the magnetic grid displacement sensor is widely used in the field of high-precision displacement measurement because of its high precision,strong anti-interference ability,easy installation and maintenance.Based on the principle of electromagnetic induction,this thesis designed a displacement measurement system based on magnetic grid with the use of STM32F415,an ARM CorteM4 based microprocessor.This system includes signal processing mainboard,excitation coils,induction coils,and steel grate ruler.The signal processing mainboard is in charge of excitation signal generation,the induction signal receiving,the displacement computation,and the UART communication.The design and debug of hardware and software of the main board is introduced in this thesis.In addition,the structures of steel grate ruler,excitation coil and induction coil are redesigned.Furthermore,high precision electronic subdivision of the induction signal is adopted to improve the precision of the system.Magnetic displacement sensor calculates the displacement according to the phase change of the induction signal,and the direction of displacement is determined through the comparing the value of phase change with 180 degree.STM32F415 generates the excitation signal with frequency of 56 kHz using timer,acquires induction signal using on-chip AD converter.The displacement is calculated using high precision electronic subdivision technology,and the measured displacement is sent to the host through UART interface.The performance of the designed displacement sensor is tested by comparing the measured results with that of laser interferometer.The testing results show that the designed sensor has the measuring resolution of 1um,and the measuring error is about 10 um within measuring range of 35 cm.The sensor has advantages of stable operation,simple structure and easy maintenance.In addition,the sensor supports non-linear measurement and has higher practicability.