Research On UUV Optimized Formation Control With Target Driven Towards Seabed Detection Mission

UUV formation usually navigates in the seabed to complete pipe detection and targetsearch mission. To guarantee the stability of formation, the whole dynamic system should becontrolled coordinately, and each member must be controlled accurately with its controllersimultaneity. With the combination of both aspects, the formation can be coordinatedsmoothly as each member maneuvers effectively. In this paper, UUV formation optimizationcontrol with target guidance in the seabed is researched intensively. Target guidance isconsidered as, that a search strategy is adjusted adaptively according to the position ofpre-searched target and the states of UUV-self during search mission using vehicle, and theultimate goal is to lock the mission swiftly.The main contents of the paper are described as following.1. A decentralized control system frame based on the decoupled system in space-time isproposed. The dynamic control of single vehicle and the coordinated formation mission formulti-UUV are decoupled. The position and attitude of each vehicle should tend to zero withits own controller, in the meanwhile, the formation control for multi-UUV will be completedwith the coordinated controller.2. Considering the significant influence from complex terrain environment in anunknown marine environment, seabed terrain model algorithm is studied as a benchmark ofUUV formation navigation. Firstly, a few discrete data in detection scopes is collected. Then,an inerratic grid model is established by choosing the appropriate scopes. Based on theinerratic grid model, mission region is reconstructed using Kriging interpolation method inspace. Finally, the data described seabed terrain information is obtained accurately and3-Dimpression (effect) image of is displayed explicitly.3. The control strategy for target searching mission is clarified clearly. On the one side,the target search in extensive area is completed with terrain following. To avoid threateningfrom seabed terrain to the vehicle during navigating, high control is present, with vehiclefollowing the fixed line composing using height. On the other side, while a certain vehicle hasdetected a target, it will notify other members, and the whole formation will be adjusted withembedded control strategy. The concrete strategy flow is that all vehicles should be divingsynchronously firstly, and then formation is constricted to target which will be locked finallywith minimum duration.4. The path following controller and coordinated formation controller are designed, and the formation optimization control is investigated further. An adaptive sliding controlalgorithm based on backstepping is introduced in the design of path following controller. Thebackstepping, sliding algorithm and adaptive theory is combined, and it makes the control ofpath following for single vehicle more effectively. An improved artificial potential fieldalgorithm is included to design the coordinated formation controller. The virtual potentialfield forces can be caused mutually by the error between real distances and desired ones toeach vehicle. The coordinated formation control can be implemented by adjusting thevelocities of vehicles based on virtual potential field forces. The genetic algorithm isintroduced to optimize gravitational coefficient and repulsion coefficient, to avoid thedisadvantage from the random selection of both coefficients. The algorithm will be utilized inthe formation optimization.5、The algorithm proposed will be validated by simulation with different cases to clarifythe feasibility for the search control strategy and the controllers designed based on formationoptimization.