Research On Machinery Equipment Condition Monitoring System Based On Wireless Channel

To improve products quality, production efficiency and reduce production cost, this paper designed a machinery equipment condition monitoring system based on wireless channel. The system is made up of data acquisition module, wireless transceiver and data acquisition platform.At present, the amplitude of the output analog signals of most sensors used at industrial fields are fluctuating in a large range. To reduce the interference and zero shift induced by separated amplifying and filtering processes, this system adopts the 16-bits analog-digital converter AD7705, which incorporates data acquisition, amplifying, filtering and A/D converting. AD7705 is a part with high resolution, wide dynamic range, self-calibration and excellent anti-noise performance, furthermore, its full differential input channels have strong anti-jamming ability against common mode signals, such as the temperature change caused by external factors. And thus high-precision data acquisition is complemented.Considering the harsh environment at fields, such as noise, electromagnet interference and signal attenuation, this paper details the key technologies in wireless communication, and then put forward a series of measures to improve stability and reliability of the system. This paper chooses the single-chip radio transceiver nRF905 to realize data communication. nRF905 is a chip with high cost performance. It adopts the strong anti-jamming GFSK modulation and with adjustable output power, integrated communication protocol and CRC code. It is insensitive to the power supply and can implement frequency hopping and transmission of 1-32 bytes data. As the result indicated, it can realize steady and reliable communication.This system has many substations and various parameters, thus data quantity is very huge. It adopts PC to process and display the received data due to the poor data processing ability of MCU. The PC communicates with wireless module through RS-232 serial port. A data acquisition platform based on Visual Basic is developed. This platform controls the substationsand the parameters being measured, it can real-time display received data and plot graph to show the changing tendency of the significant parameters of machinery equipments.To improve the precision and reliability, this paper also details the anti-interference measurements in hardware and software. As the results at fields indicated, this system can implement high-precision data acquisition and no error code indoor data transmission in 50m scope, it can also penetrate 4 walls and with strong anti-jamming ability against CNC machine, air compressor, crane, welder and other machinery equipments in machining workshop. And the detailed experiment results are presented in this paper. Based on the test results, we can say that this system can meet the machinery equipment monitoring requirement at most industrial fields.