Research On Virtual Mooring Control Of Underwater Gliders

As a new type of underwater monitoring instrument platform,underwater gliders have the advantages of long running time,wide application range and low cost.Currently,they are mainly used for large-scale,long-time observation and detection of the ocean.In addition,underwater gliders can also be used as virtual mooring observation equipment to perform fixed-point or fixed-depth mooring observations.Compared with traditional mooring observation equipment,the virtual mooring of underwater gliders has the advantages of low cost,simple deployment and easy maintenance,and thus are more suitable for mooring observation.At present,only a small amount of exploration has been carried out abroad on the use of underwater gliders for virtual mooring observations.Domestically,study on this aspect is still in its infancy,and a lot of research work has yet to be carried out.To this end,this paper takes the Petrel-Ⅱ underwater glider independently developed by Tianjin University as the object to carry out research on virtual mooring motion control of underwater gliders.The main research results and innovations are as follows:1.Based on the analysis of the dynamic characteristics of the Petrel-Ⅱ underwater glider,the Newton-Euler method was used to establish its spatial six-degree-of-freedom mathematical model,and the influence of the current on the kinematics of the underwater glider was considered.Combined with the dynamic characteristics of the virtual mooring movement,the mathematical model of the virtual mooring movement of the underwater glider was obtained,which lays the foundation for the subsequent simulation analysis.2.Analyzed and modeled the disturbing factors of the virtual mooring motion of the underwater glider,including the initial imbalance,shell compression deformation,seawater density and temperature changes,and current interference.A buoyancy-drive system that can perform virtual mooring operations is designed,and its performance is verified through experiments.Based on the experimental data,a mathematical model of the buoyancy drive system oil return/discharge process is established.The virtual mooring interference factors and the buoyancy drive system oil return/discharge model are combined.A net buoyancy mathematical model that can accurately describe the virtual mooring operation of underwater gliders is obtained.3.To solve the problems of nonlinearity,strong coupling and parameter uncertainty of the underwater glider system,a BP(Back Propagation)neural network PID self-tuning virtual mooring motion controller based on GA(Genetic Algorithm)is designed and the effectiveness of the controller is verified through simulation and experiment.