Development and test on three dimension force monitoring system for farming machinery based on wireless sensor network

Abstract: With energy consuming seriously increasing, energy conservation became important in every industry. In agricultural areas, focus was fixed on the energy conservation of farming machinery. An effective way to analysis energy consumption and work efficiency by measuring the force of the key part of farming machinery became a hot research topic due to the fact that the force could partly reflect the energy consumption and work efficiency of farming machinery. In this paper, a remote real time monitor system based on WSN was designed for the purpose of monitoring three dimension forces on farming machinery during work time, and meantime it was able to give alarm when the monitored signal was out of the pre-supposed range. For measuring and transmitting sensors' signal, the system adopted the Zigbee protocol based WSN to realize data acquisition and transmission. A wireless data collector was designed with a JN5139 wireless module as its main processor, in which an analog signal adjusting circuit was designed for measuring different range signals. The JN5139 module has a serial interface with TTL signal output, in order to connect the collector to a computer by a serial interface cable, a TTL to RS232 signal circuit was necessary. In addition, the collector's power consumption was supplied by a rechargeable battery, and a power management circuit was required. For exchanging, processing and monitoring data from WSN, an embedded processor ARM11 was put to use as the central processor unit of the monitor device, and on which, a Wince6.0 software environment was established. For watching and operating easily, a human-computer interface software was developed under VS2005 by the C++ programming language. By the help of the human-computer interface software, the serial interface parameter could be set for matching the serial interface in collector and the three dimension forces threshold could be set ether for giving alarm and besides, the monitor data could be saved to a storage device for further research. Six tension sensors were fixed on a portal frame made of plates which was finally fixed on farming machinery in particular positions as a force transmission structure between the tractor and farming machinery, by which the tension signal was measured. For testing the performance of the monitor system, a farming machinery three dimension forces monitor experiment was made on soil-bin. The curves of three dimension force and torque indicated that with the deepening of tilling depth, three dimension forces created by farming machinery was increased, which indicated that the tractor power output was also increasing. A three dimension forces monitor system based on WSN research showed that the system was not only stable and reliable on data acquisition and transmission, but also gave an alarm when the tension signal got out of a pre-set range, and it realized three dimension forces of farming machinery monitor and data store with a good operable human-computer interface, besides, the system solved cabling difficulty, poor extensibility in three dimension forces monitor by way of a wire. Research results indicated that the system could be used to monitor three dimension forces of farming machinery in real time, which could contribute to the research of the design of farming machinery.