Design Of Mechanical Vibration Wireless Sensor Networks Synchronous Acquisition Node Based On Crystal Offset Compensation

The mechanical vibration wireless sensor networks has the characteristics of distributed,self-organized,strong dynamic,flexible deployment and so on.It has great potential in the field of mechanical vibration monitoring.The vibration signal of mechanical equipment has the characteristics of weak signal,wide frequency range and synchronous acquisition of multi measuring points.The acquisition node of mechanical vibration wireless sensor networks not only has high acquisition precision and high sampling frequency,but also a high precision synchronous acquisition between each node is also a key index.Under the condition of high acquisition accuracy and high sampling frequency,the accuracy of synchronous acquisition is higher and it is more difficult to achieve.On the premise of meeting the high precision acquisition and high frequency acquisition of mechanical vibration signals,the paper studies how to improve the accuracy of synchronous acquisition.The specific work is as follows:The hardware design of synchronous acquisition node for mechanical vibration wireless sensor networks with high precision and high frequency acquisition is designed.A dual core processor architecture is designed to avoid the coupling between network maintenance tasks and data collection tasks,and achieve high frequency acquisition of mechanical vibration signals.A hardware cross layer circuit with is designed to reduce synchronous information transmission delay and provide precise time reference for high precision synchronous acquisition.A Multichannel power management of hybrid power supply and an IEPE sensor drive circuit with self-suppression of power noise are designed.The power conversion efficiency of digital circuits and the power supply quality of analog circuit power supply are taken into account.At the same time,it is compatible with IEPE accelerometer with high sensitivity,wide measuring frequency range and low noise density.An anti aliasing low pass filter with adjustable cut-off frequency and a gongsignal differential circuit are designed to effectively filter the high frequency noise and suppress the common-mode noise.Using the 24 bits SAR ADC with continuous high frequency sampling clock,the performance requirements of the node power and synchronous acquisition function are taken into account under the premise of guaranteeing the accuracy of analog to digital conversion.A high speed data access circuit is designed to enhance reliable cache for a large number of vibration data.Through the above hardware design,the synchronous acquisition node achieves high precision and high frequency acquisition of mechanical vibration signal,and provides a reliable hardware platform for synchronous acquisition.The method of synchronous accumulation error suppression for mechanical vibration wireless sensor networks is studied and a software program of the synchronous acquisition node core 1 is designed.In view of the high precision ADC with continuous high frequency sampling clock,the cause of synchronous accumulative error is analyzed.A synchronous cumulative error suppression method based on the compensation of crystal offset is proposed to solve the problem of continuous accumulation of synchronization errors in the acquisition process.The main program flow of processor core 1 is designed to achieve real-time scheduling of corresponding tasks.Reliable data storage method and data transmission software using multi cache mechanism are designed to ensure the reliability of storage and transmission of large amounts of vibration data.The main function modules and user interface of host computer monitoring and management software are introduced.Integration of monitoring system for mechanical vibration wireless sensor networks.The overall structure of monitoring system for mechanical vibration wireless sensor networks is introduced.Hardware integration of gateway node,routing node,acquisition node and vibration acceleration sensor is completed.Finally,the application test of modal parameter identification is carried out.The result shows that the synchronous acquisition node of the mechanical vibration wireless sensor networks designed in this paper can achieve high precision and high frequency synchronous acquisition of mechanical vibration signals.