Research Of The Descent Process And Multi-objective Optimization Analysis Of A Benthic Lander

Because of its simple structure,relatively low cost,long-term work and reuse,benthic landers are widely used in marine biological research,marine environmental monitoring and other fields,and are indispensable underwater delivery equipment for marine scientific research and resource development.In the traditional design process of benthic lander,there is a problem that it is difficult to select the velocity during the decent process,which is shown as follows: the decent velocity is too slow and takes up limited ship hours;If the decent velocity is too fast,it will lead to problems such as too large subsidence depth,which will further lead to the failure of observation functions or retrieval failure of the lander.However,the method of constantly adjusting the configuration of landers(such as the number of floating spheres,the mass of weight stack,etc.)and conducting multiple tests has the problems of long research and development cycle and large investment.Therefore,the research on the descent process of the lander and the optimization design of its buoyancy unit configuration are important issues in the application of benthic lander.Therefore,this research focuses on the descent process of benthic lander and the optimization of its buoyancy configuration,and carries out the following research:(1)According to the task demand,the structural characteristics of the lander are analyzed,and the dynamic model of the benthic lander’s decent process is further established.The weight stack of the land implements uses a new plate structure,which is mainly intended to accommodate more microbial enrichment devices and facilitate the automatic closure of enrichment devices.(2)Using Computational fluid dynamics(CFD)technology,the hydrodynamic coefficients in the dynamic model of the benthic lander’s decent process are calculated.This part focuses on the calculation process of added mass coefficients,and introduces the spherical study,in which the relative error between the calculated value of CFD with added mass and the theoretical value is 5.7%,which verifies the correctness of the CFD calculation method adopted in this part.(3)Based on MATLAB platform,the simulation analysis method of benthic lander decent process is established.Using MATLAB Simulink environment,the dynamic model of the benthic lander decent process is simulated and solved;then the platform for Evolutionary Multi Objective Optimization(Plat EMO)is used to study the mutual restriction between the configuration of the lander and the descent parameters,get a range of preferred schemes.(4)According to established dynamic model and simulation analysis method,the sea trial under the specific buoyancy configuration of the benthic lander is compared with the corresponding scheme in Multi Objective Optimization,and the following conclusions can be obtained by comparing the simulation and optimization analysis results with the sea trial data: the average descent velocity obtained by Simulink simulation and the sea trial were 0.81 m/s and 0.77 m/s,respectively.Secondly,the relative error between the descent time calculated by multi-objective optimization and the descent time of the sea trial is 5.1%.