دانلود رایگان مقاله انگلیسی دو ترموکوپل کم قدرت شبکه سنسور بی سیم - الزویر 2018

Abstract:

This paper presents technologies and experiments of a wireless sensors using two thermocouples network. It was established that the energy consumption during sensor measurements is usually up to 10 times lower compared to the energy consumption at the time of establishing wireless connection for most protocols. For this reason, new simplified wireless connection protocol was created. Extremely low energy wireless sensor hardware and software equipment was designed. The newly created universal measurement module allows the use not only thermocouples, but also various types of analogue sensors, thermocouples, pressure bridges, Resistance Temperature Detectors (RTD) and digital sensors communicating through SPI or I2C interface. The newly designed specific power supply scheme allows to supply the sensor and radio module with the voltage from 1.2 V to 3.6 V batteries. When conducting periodic measurements every second, the use of newly designed hardware and software equipment enables the wireless sensor to be operated for up to 3 years from two 1200 mAh capacity batteries.

4. Conclusions

The system for gathering information from wireless sensor comprises a specific protocol and functionality algorithm which ensure the minimum operation time of the radio module. The prototype of the concentrator and the relevant highly effective microcontroller software which enables fast processing of the received data have been designed. Three independent communication interfaces - USB, RS-232 and RS-485 - operating in parallel mode and aimed at connecting different types of equipment have been foreseen. The support for Modbus RTU protocol enabling to read data using a computer and SCADA software or other compatible industrial equipment has been realized. The possibility to remotely monitor the state of wireless sensor feed elements, the quality of network and the loss of data has been realized. The methods of reducing and optimizing wireless network energy consumption have been thoroughly researched. The measured distance of wireless sensor operation subject to direct visibility is 150 meters. The experiment was conducted with 15 wireless sensors for 1 year. Upon evaluating the obtained results, it is safe to say that when periodically conducting measurements every second a wireless network receiving energy from two 1200 mAh capacity alkaline NiMH AA battery can operate up to three years and minimum one year when connectivity is excellent. subject to sufficient signal level and up to seven months with no access to the concentrator. Reducing temperature measurement frequency results in a proportional increase in operating time from limited power source. The designed system uses the maximum of 5 mA to measure and send data while peak power requirements for BLE is 12–15 mA, ANT – 17 mA, ZigBee varies from 17.6 to 29 mA.