Development Of ARM-based Wireless Conditon Monitoring System For Mechanical Transmission Equipment

The mechanical transmission equipment has been widely used in modern industry,its condition directly concerns the safety and reliability of the whole system. Along with the degree of automation and precision of machinery equipment is higher and higher, it puts forward higher requirements for the monitoring system of mechanical transmission equipment. The traditional monitoring system for mechanical transmission equipment generally uses sensors outside the box to sense the vibration signal caused by mechanical transmission equipment. This method has the disadvantages of poor original signal component,high noise,large volume,high price and poor environmental adaption ability, making it difficult for researchers to do signal analysis and fault diagnosis. Therefore, it’s urgent to develop an efficient monitoring system for mechanical transmission equipment.This paper studys the ARM-based wireless conditon monitoring system for mechanical transmission equipment, to adapt to the special mechanical environment where has closed case,oil,gas, high temperature,high speed,variable speed and variable load. This system uses acceleration sensor to directly obtain the vibration signal caused by local changes inside the mechanical box, then sends the data collected by sensor to receiving terminal, and the receiving terminal transmits the data to upper computer via USB. The upper computer can display, store and analyse the data. Considering the mechanical environment is complex, this paper adopts the method of signal relay, in order to increase the transmission distance of the wireless signal. The system consists of data acquisition node, relay node and receiving terminal.The system uses ARM based on Cortex-M3 architechture as the main controller, and adopts μC/OS-II operating system to enhance the scalability and reliability in both hardware and software. The software on the μC/OS-II can be cut according to the specific function for each node. Data acquisition node sends the data acquired by sensors through wireless transmission module and stores the data in large capacity NAND Flash at the same time. In order to guarantee the safety of data, ECC algorithm and bad block management algorithm are used when designing storage software. Due to serious signal attenuation inside the mechanical environment, this paper adds a power amplifier(PA) and a low noise amplifier(LNA) in the wireless transceiver circuit for acquisition nodes to enhance the transmission power and receiving sensitivity of wireless signal. Meanwhile, in order to ensure the success rate of wireless transmission, this paper sdudys the reliable communication mechanism based on AT86RF212 and IEEE.802.15.4 protocal, and successfully implements the frame retransmission mechanism based on ACK,address filtering and frame check security mechanism. In addition, this system uses the battery as the power, especially for the data acquisition node which is inside the mechanical box and can’t be easily taken out, so the power consumption must be considered. This paper is on the basis of stability and reliability of wireless transmission and adopts the method of intermittent power supply for power amplifier circuit and automatically entering sleep mode to reduce part of the power consumtion for data acquisition node.Finally, this developed system is applied to monitor the fault gear in gear box in the mechanical transmission laboratory, the experimental results show that the system can real-time acquire the the gear fault signal. This experiment achieves good effect and the system can meet the requirements of miniaturization, anti-interference, low power and the reliability of wireless transmission.