中文摘要：

井下煤层对无线信号有很强的吸收作用，因此，无线通信的距离十分有限，必须通过中继模块来续传无线信号。本文设计了一种装置，在得到指令后，可实现抛投通信中继模块的功能。并且试验证明，此装置能保障煤矿救灾机器人与救灾指挥控制端之间的无线通信畅通。

英文摘要：

The wireless communication signal is mostly absorbed by coal seam, so the wireless distance is limited and the signal must be transmitted continually by relay module. This paper designs a device which can cast the communication relay after receiving an instruction. And the experiments prove that the casting device can ensure the fluent wireless unit.