Design And Achieve Of Autonomous Underwater Survey System

There are very strict water quality requirement for aquaculture.The corresponding sensor are installed at a fixed position to sample the water quality or the investigators test the water quality manually randomly.These kinds of methods have the problems that the costs for detections are expensive,a lot of time is spent and the final result of the water quality survey is inaccurate.Therefore,this thesis designs an underwater survey system used for underwater water quality survey to solve above problems.It has multi-freedom movement and adopts the vision-based method to realize automatic localization and navigation.In this thesis,after the analysis of the requirements,the system needs to have the following functions.It can realize four-degrees of freedom motion.It has the ability to detect obstacles in the direction of advancement and realize self-motion detection.Also different types of sensor systems are required to carry with and modular assembe functions are needed when the focus of survey is different.Based on the above analysis of function requirements,this thesis designs the mechanical structure and control system of the underwater survey system.The four propellers are used to realize the four-degrees of freedom movement of the underwater survey system,and the structural design of several modular subdivisions are carried out.Visual survey module is used to detect obstacles,and multiple sensors can be mounted on the middle cabin.The modeling analysis of the kinematics and dynamics are given.and the flow simulation of the system in underwater motion is provided.For the heading and depth control requirements during unzderwater movement,this thesis designs double closed-loop PID motion control scheme in the heading movement and depth movement respectively.Based on the above design scheme and related method,the prototype is produced.After building the hardware system and programming related control code,the underwater experiments related to the prototype are carried out to verify the design functions.The experimental results show that the system can achieve the expected design targets.