Design Of Water Quality Monitoring System For Unmanned Ship And Optimization Of Monitoring Points

With the gradual enhancement of people’s awareness of environmental protection,the issue of water resources has received widespread attention.Through reasonable monitoring methods,quickly and accurately grasp the data of water quality changes,and serve the relevant departments to assess and treat the water quality status,which is the key to the scientific protection of water resources.However,the existing water quality testing methods often rely on large-scale water quality analysis equipment,through manual point-by-point sampling back to the laboratory for accurate analysis.Although the analysis results obtained are more accurate,ensuring certain timeliness and time continuity is difficult.In the face of a complex and changeable sampling environment,the operation difficulty of the staff is greatly improved,and operational safety is difficult to guarantee.With the development of science and technology,fixed-position automatic water quality monitoring stations and manned water quality mobile monitoring equipment have alleviated the above problems to a certain extent.However,fixed monitoring stations or water quality buoys can not be actively moved.In the occurrence of sudden water pollution problems,water quality monitoring work is very passive,and it is challenging to locate the location of pollution sources;manned water quality mobile monitoring equipment（such as manned water quality monitoring ships,water quality collection vehicles）is not only costly and easy to produce secondary pollution,in some small and medium-sized waters,but also exposed to complex to transport,bulky and inflexible and other issues.In small and medium-sized waters,water quality changes relatively frequently and is susceptible to environmental,weather,and artificial and seasonal changes.For the monitoring scenario where water quality fluctuates significantly over time,it is urgent to design flexible,portable,low-cost online water quality monitoring equipment.Based on the analysis of the current situation of water quality monitoring at home and abroad,this paper designs a lightweight water quality monitoring unmanned ship system.The system has the characteristics of remote signalling interaction,low cost,high detection accuracy,and flexible mobility,which it can use for water quality information monitoring in small and medium-sized waters.The main contents and innovations of this paper are as follows:（1）An unmanned ship system for water quality monitoring is designed based on the needs of small and medium-sized water quality monitoring scenarios.The system is divided into the unmanned ship,remote data display terminal,and host computer control terminals.The unmanned boat is equipped with four high-precision water quality sensors of REMOND Company,relying on the Beidou-GPS dual-mode positioning unit,attitude detection unit,and obstacle avoidance unit to sail to the desired position collect upload water quality data to the remote data display terminal.Unmanned ships use the Free RTOS operating system to efficiently schedule tasks such as sampling,cruising,and communications.Remote data display terminal and unmanned ship through narrow Band Internet of Things（NB-Io T）technology to complete signalling interaction,mainly to achieve remote data collection and visualization.The host computer control end designed with QT Creator can more easily interact with the data of unmanned ships,which is convenient for use in particular application scenarios such as debugging and artificial data collection.Compared with the current water quality sampling method,the lightweight unmanned boat system is more suitable for small and medium-sized water quality monitoring.（2）For the unmanned ship water quality monitoring scenario,the optimization algorithm of the traditional monitoring node layout is improved.In this paper,the more mature and representative node layout optimization algorithms in the atmosphere,noise and water quality monitoring are introduced: fuzzy clustering method,object-element analysis method and dynamic closeness method,and the functional areas and restrictions of traditional optimization methods are analyzed.Aiming at the characteristics that unmanned vessels can actively collect water quality information,the conventional dynamic paste progress optimization algorithm is proposed,and the genetic algorithm is used to optimize the cruise path.In the water quality testing experiment of the lake,the optimized node layout algorithm saved an average of 14.85% of the driving distance.（3）The system’s essential functions,such as communication quality,autonomous cruise accuracy and water quality sampling accuracy,were tested,and water quality monitoring experiments were carried out in small lakes.Experimental results show that the packet loss rate between unmanned ships and host computer control terminals,and remote data display terminals does not exceed 0.7% and 2.3%,respectively.The motion control system can follow the step signal,ramp signal and acceleration signal to ensure cruising accuracy and sensitivity.Although the sampling accuracy of water quality sensors can be affected by complex working environments,they still maintain high accuracy after sliding average filtering.The water quality monitoring experiment verifies the system’s stability and demonstrates the practicality of the improved dynamic proximity algorithm.