Research On Mechanical Vibration Piezoelectric Monitoring System

Stablility,safety,and efficient operation of machinery are of fundamental importance in reducing unnecessary downtime and preventing accidents in industrial production.Vibration monitoring technology can acquire the vibration information of the equipment in real time,keep track of the working status of the equipment,and give an early warning of abnormal status of the equipment.A low-power smart screw for monitoring equipment vibration has been studied and designed in this paper.The smart screw mainly consists of a piezoelectric vibration sensor unit,an information processing circuit,and a wireless data transceiver module.This smart screw integrates a lightweight vibration monitoring algorithm that enables on-line monitoring of instrumental vibration.After interconnecting multiple smart screws through a central computer,a vibration monitoring network can be formed to achieve real-time monitoring of multiple nodes of mechanical equipment.The RS-485 serial communication is used between the upper and the central computer,and the reliability of data transmission is guaranteed by Cyclic Redundancy Check(CRC).The main work of this thesis is as follows:(1)A vibration simulation platform was developed.The vibration stage is driven by a voice coil motor,and the driving signal of the voice coil motor is output from a function generator.Vibration frequency and amplitude of the vibration stage is handfully adjustible.(2)The piezoelectric vibration sensing unit has been developed.The piezoelectric ceramic PZT works as the vibration-to-electric convertor.The fixation installation method of the sensor is determined by modeling buzzing film with finite element method(FEM),and the design scheme of the vibration sensor with high eigenfrequency is obtained with the FEM analysis of the sensor.Finally,the piezoelectric vibration sensor module has been developed have a good frequency response within the range of30 Hz ~ 1000 Hz.(3)The wireless data transmission module has been design and implemented.Using a low-power MSP430FR5969 micro-controller as the information processing unit,the wireless data transmission between the smart screw and the central unit is achievedthrough the CC110 L RF module.According to the test results,the smart screw developed in this paper has good wireless data transmission ability within 40 meters.(4)The vibration monitoring algorithm has been designed and implemented.In this paper,a status-monitoring algorithm based on fast Fourier transform(FFT)and spectrum comparison algorithm is implemented in the smart screw.The status-monitoring function of the device can be realized by this algorithm.In the upper computer level,MATLAB is used as a platform to perform the time-frequency analysis of the vibration signal to determine the stability of working status of the equipment.(5)The network operation of the smart screws was realized.The smart screw is organized by a customized data frame format,and each screw is coordinated by the central computer,and the vibration data and state monitoring information of the multi measuring nodes of the mechanical equipment are collected.(6)The vibration monitoring system was tested under the actual working conditions.The test results show that the smart screw studied in this paper can correctly separate the different working status of the grinding machine and realize the state monitoring function of the equipment.