水下机器人集群通信系统设计及实验分析

For the practical application of the underwater robot cluster communication platform, there are the problems of the Doppler effect and bit errors generated due to susceptibility to water quality and obstacles. In this paper, an underwater bionic electric field communication system based on the perception mechanism of weak electric fish is proposed. According to the principle of bionic current field communication, the communication system transmits signals through two pairs of transmitting and receiving electrodes. A set of digital-analog hybrid circuit using field programmable gate arrays (FPGA) based on the principle of amplitude shift keying is designed. At first, to achieve a miniaturized system with low power consumption, the analog circuit is reasonably selected by the component model. Circuits are placed, routed and patterned. The specific transmitting circuit includes an amplitude shift keying modulation circuit and a half-bridge drive amplifier circuit. The potential difference between the two ends of the receiving electrode is extracted by using a low-zero-drift high-precision instrumentation amplifier. Secondly, in order to improve the stability of the communication system when the communication distance of the underwater robot cluster changes in real time, the programmable amplifier is controlled by gain control digital circuit in the FPGA to realize the adaptive multiple amplification. Then this system uses analog-to-digital conversion digital drive circuit in FPGA to drive the analog-to-digital conversion chip to convert analog signals into digital signals. Finally, after the signal is rectified by the rectification filter digital circuit, the amplitude shift keying non-coherent demodulation digital circuit is designed to output the binary demodulation data. The signal is transmitted to the Raspberry Pi through the serial port circuit for processing. The influence of obstacles of different sizes and different shapes on underwater electric field communication is simulated and analyzed, and the underwater communication experiment is carried out. The results show that the underwater electric field communication system can transmit information with a bit error rate of 0 when the communication distance is 2.4 m under the condition of conductivity of 4.87×10^-4 S/cm in fresh water. When the transmitting and receiving electrodes of underwater electric field communication are parallel, the communication performance is the best.