Vibration Measuring Instrument Design Based On Single-chip Microcomputer

Aero-engine is an important part of aircraft,whose performance determines the flight safety of aircraft.At present,the thrust,rotation speed,and dynamic strength of aero-engine are increasing,the vibration problems caused by rotor unbalance and gas flow are becoming more and more prominent.The engine works in the harsh environment of high temperature,serious oil mist,and electromagnetic interference.It is necessary to select the appropriate vibration sensor and vibration measuring instrument to measure the vibration value of the engine quickly and accurately.This is of great significance to the improvement of test safety and engine reliability.In this thesis,a vibration measuring instrument based on single chip microcomputer is designed,which can detect the vibration state of aircraft engine completely and systematically with engine in operation,and analyze the running state and basic performance of engine accurately and effectively.The aircraft engine runs continuously,healthily and stably,which lays a good technical foundation for safe flight and troubleshooting of aircraft.Therefore,the study of the paper has a very important practical significance.This thesis firstly analyzes the advantages and disadvantages of the existing special vibration measuring instruments for aircraft engines at home and abroad.Aiming at the problems,a new type of vibration measuring instrument based on MC9S12XS128 single chip microcomputer and Freescale is designed,which can overcome the shortcomings of the existing instruments.The theoretical basis of designing the instrument and the chip selection basis and debugging result of each hardware module function are discussed.In the hardware design,because of the high operation speed of MC9S12XS128,the expensive programmable bandpass filter UAF42 AP is saved and the circuit design is optimized at the same time.Through measuring vibration speed by special effective value measuring circuit and measuring frequency by frequency-pressure conversion circuit,the disadvantage of poor stability of counting and measuring frequency can be overcomed,and then A/D conversion can be carried out by using two-channel A/D conversion circuit.The conversion result is sent to MC9S12XS128 single chip microcomputer for data processing,and then the conversion result is displayed by digital tube using LED driver chip MAX7219.In the part of software design,the flow chart of modular software design based on MC9S12XS128,the design of A/D conversion and display program are introduced firstly,and then the precision,stability and improvement measures of the instrument are analyzed according to the measured data.Finally,through repeated simulation measurement and verification,this vibration measuring instrument has achieved the expected goal of the design.The error is less than 3%,and the measurable frequency range is 10Hz~2000Hz,which meets the requirements of measuring precision and measuring range.