Research On Multi UUV Formation Control Based On Finite Time Extended State Observer

Due to the continuous development of terrestrial resources,the resources that can be developed on the land are about to be exhausted.The problem of energy scarcity has become a major problem that all countries in the world need to solve urgently.More and more countries are gradually shifting the focus of resource development to the sea.Because the deep sea environment is more severe and dangerous than land,the Unmanned Underwater Vehicle(UUV),for short,has an irreplaceable role in the field of ocean exploration.As the difficulty and complexity of ocean exploration missions increase,a single UUV can no longer meet the work requirements.Therefore,the coordination of multiple UUVs to complete tasks in a cluster has become the inevitable direction of development facing the present and facing the future.This paper takes a group of under-driven UUVs as the research object,based on the leader-follower formation strategy,to realize the design of multiple UUV formations.Based on the establishment of UUV kinematics and dynamics models,a double closed-loop control system is established,and a finite-time controller is designed using the idea of an integral terminal sliding mode control algorithm to deal with the trajectory tracking problem in the formation system.At the same time,taking into account the UUV’s external interference and the parameter uncertainty of its own system,the problem is effectively solved by designing a finite time extended state observer.The specific research content is as follows:First,by establishing a global coordinate system and a body coordinate system,the kinematics and dynamics models of a single UUV are analyzed and structured.Taking into account the under-driving characteristics of UUVs,the established model is divided into under-driving parts and non-under-driving parts.The complexity of the controller design is reduced,and the formation matrix of the followers L-φ in the UUV formation system is constructed according to related requirements to complete the formation design.Secondly,considering that UUV is in the actual complex sailing environment,it will be subject to external interference and the influence of parameter uncertainty of UUV model on the control system,based on the analysis of finite time control theory,this paper combines the ESO with finite time convergence theory,and designs an ESO converging in finite time to estimate the influence of environmental disturbances and system parameter uncertaintyFinally,aiming at the shortcomings of most asymptotically convergent formation controllers,combined with the idea of finite time control,a double closed-loop control system is established in this paper and uses an integral terminal sliding mode control algorithm to make the UUV’s pose and speed in the formation system The error converges in a finite time.At the same time,considering the chattering of SMC,the boundary layer method is adopted,and an adaptive law is designed for the boundary layer parameters and switching gain coefficients,so as to reduce the negative impact caused by the chattering,and the finite time control theory is used to analyze the stability of formation control system.According to the results of theoretical analysis and simulation experiments,the observation effect of the finite time extended state observer can achieve the expected effect.At the same time,the UUV formation can be completed in a finite time.After adding the adaptive boundary layer and switching gain coefficient,the chattering situation is obviously weakened,and the motion tracking state of each UUV is good,which proves the correctness and effectiveness of the method proposed in this paper.