| Deep ocean is an important regulator,for which it is of great scienti c signi cance to promote the multidisciplinary,long-term and high spatial-temporal resolution observations.Focusing on the important scienti c problem,i.e.the role of deep ocean in the global climate system,this thesis aims to develop a new mobile observation platform,a hybrid deep-sea oat.In the present study,a hybrid deep-sea oat able to switching between the Argo and Glider modes is proposed,which can achieve long-time,multidisciplinary,large-depth and three-dimensional observation duties.As a new type of platforms,for oceanographic observation and ocean resource exploration,it is of great signi cance to oceanographic researchers.When it operates under the Argo oat mode by periodically adjusting its static buoyancy,the platform is able to hover at a designated water depth and dive/climb at a certain speed for an observation of target sea area with good e iciency and long durance capability.While working under the Glider mode,the platform's attitude can be e ectively adjusted to glide forward due to the lift force provided by its wings,which makes it possible to track and observe a moving target within a vast sea area.On the basis of traditional underwater observation platforms,a strategy to switch between the Argo and Glider modes is proposed in this thesis.Simulations and experimental tests are carried out for the new platform,and the results are analyzed to verify its feasibility.A nonlinear controller with multiple inputs and multiple outputs is developed,by establishing a kinematic model for the platform,tailoring the hydrodynamic models and parameters,and analyzing the stability of the platform under various modes.Numerical simulations are then carried out focusing on the modeling of the gliding motion in a three-dimensional space and mode switch.A full scale prototype of multi-mode deep-sea mobile observation platform is successfully built and studied extensively via multiple lake tests,sea trials and simulations.The main original and innovative contributions of this thesis are summarized as follows:1.Based on the two traditional types of underwater observation platforms,i.e.Argo oat and Glider,a new type of oat with the capacity to switch between Argo and Glider modes is proposed.This new platform is able to perform large-depth lurking observation tasks for vertical pro les as well as long-distance zigzag missions.A new mode switch strategy enabling multiple functions in di erent modes is proposed for the novel deep-sea multi-mode mobile observation platform,and is realized by modifying design principles of the conventional underwater vehicles.This strategy requires a unique attitude control system to regulate the position of the center of mass in a wide range.Therefore,the vehicle can achieve the extreme large attitude of 90?pitch angle,which fails in conventional underwater vehicles because of its singularity.The accuracy of the physical parameters and precise distributions of the components as designed,are very important to the realization of the mode switch strategy.To achieve the design objectives,each subsystem is carefully designed,including the pressure hull,attitude adjustment system,buoyancy adjustment system,energy system and low-power control system.2.The variation of the deep-sea oat's gravity/buoyancy center due to Argo-Glider mode switching is taken into account.A complete dynamic model is thus established based on the Newton-Euler formulation,and its hydrodynamic performance considering attitude variation is analyzed.The e ects of the attitude control system and the relationship between the gravity center and buoyancy center are considered while establishing the complete dynamic model.Hydrodynamics of the proposed vehicle is analyzed for the gliding performances of the vehicle in glider mode like lift-to-drag ratio,side force,turning ability,positive and negative spiral motion patterns with the aid of computational uid dynamics(CFD)technique.3.In order to satisfy the needs of stable motions for the oat in multiple modes,a nonlinear adaptive inverse controller with multiple inputs and multiple outputs,is developed based on the Lyapunov stability criterion which enables the observation platform to freely switch between various modes.Then,multi-mode motion control simulations in a three-dimensional space are achieved.By further analyzing the dynamic model,the responses of the hybrid deep-sea oat under three steady-state conditions are studied both analytically and numerically.4.On the basis of detailed performance testing,analysis and optimization of its subsystems,various lake tests and sea trials were performed for the oat,and its mode switching and motion stabilization capabilities were veri ed.All subsystems of the vehicle were tested to verify the key techniques adopted.Analysis was carried out regarding the battery life of the platform,and optimization strategies were put forward,laying a solid foundation for the integration of all subsystems into a complete platform as well as subsequent testing.Based on the results of theoretical studies and model testing of the subsystems,a hybrid deep-sea oat with a maximum diving depth of 4000 meters is integrated.A series of land and basin tests were carried out,which successfully veri ed that the present design is feasible.Subsequently,a large number of lake tests and sea trials were performed to evaluate the performance of the platform from various aspects.It is shown that the platform developed in the present study is reliable and is capable of the oceanographic observation in the sea,e ectively ful lling the objectives of this research. |
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