基于LoRa通信的无线液压支架压力传感器设计

Design of wireless pressure sensor of hydraulic support based on LoRa technology

针对煤矿顶板压力监测系统中的无线ZigBee传感器使用时间达不到设计预期、需频繁更换电池的问题,设计了一种基于LoRa通信的无线液压支架压力传感器。内嵌LoRa模块的无线液压支架压力传感器安装在液压支架上,采集液压支架前支柱、后支柱及前伸梁的压力值。被测液体介质通过导压孔加压到传感器压阻元件上,压阻元件受压发生形变,产生与压力线性相关的阻值变化;传感器的微控制单元测量加在电阻上的电压,将其换算成实际压力值。该传感器实现了煤矿顶板压力监测信号的远距离、低功耗、高可靠性无线传输:通过高扩频因子的直接序列扩频技术提高接收端灵敏度,获得较高的信号增益,从而增加通信距离;通过前向纠错编码技术提高传输可靠性;采集液压支架压力值并成功发送数据后进入休眠模式,以降低功耗。测试结果表明,该传感器1h的平均功耗为1.18mA·h,容量为5000mA·h的锂电池理论续航时间为141d,满足煤矿使用要求;与ZigBee技术相比,LoRa有效通信距离更远,可靠性更高。

In coal mine roof pressure monitoring system,the issues of wireless ZigBee sensors are not being long-lasting as designed and requiring frequent battery replacement.Hence,a wireless pressure sensor of hydraulic support based on LoRa technology is designed to address these problems.The wireless pressure sensor embedded LoRa module is installed on the hydraulic support to collect the pressure values of the front pillar,the rear pillar and the forepole.The measured liquid medium is pressurized to the piezoresistive element of the sensor through the pressure hole.The deformation of the piezoresistive element under pressure produces resistance change which is linearly related to pressure.The micro-control unit of the sensor measures the voltage which applied to the resistance and converts the voltage to the actual pressure value.The sensor achieves wireless long-range,low-power and high-reliability transmission of the coal mine roof pressure monitoring signal by using three methods:the direct sequence spread spectrum technology with high spread spectrum improves the sensitivity of the receiving end,achieves high signal gain and increases the communication distance;the forward error correction coding technology improves the transmission reliability;the sensor enters sleep mode to reduce the power consumption after collecting the pressure value of the hydraulic support and sending the data successfully.The test results show that the average power consumption of the sensor is 1.18 mA·h for 1 hand the theoretical endurance of the 5,000 mA·h lithium battery is 141 days.The sensor performance meets the need of coal mining.Comparing with ZigBee technology,LoRa shows better performance for long-range transmission and higher reliability.