Research On Control Of Underwater Vehicle Based On Port-Hamiltonian

Unmanned underwater vehicles are one of the most important tools for people to explore the ocean because they can replace people to carry out underwater exploration,inspection and maintenance by equipping relevant sensors and have irreplaceable practical significance in both civil and military fields.At the same time,as a multidisciplinary,strongly nonlinear and highly coupled carrier,its controller becomes a pivotal issue and is one of the difficult and hot research points.This study designs a controller for an unmanned underwater vehicle based on the Port-hamiltonian theory and designs a full-dimensional velocity observer for vehicle.The main aspects of this paper are as follows:(1)Port Hamiltonian system has a clear physical interpretation and a clear structure that can describe a wide variety of nonlinear system models,which is used in this paper to design the controller and to prove its stability on the basis of classical dissipation theory and passive theory,as well as the theory of energy shaping.(2)A trajectory tracking controller based on Port-controlled Hamiltonian theory is designed for the motion control problem of underwater vehicles with parameter uncertainty and external environmental disturbance conditions.Firstly,the classical mathematical motion model of the vehicle is established,and the Port Hamiltonian theory is applied to transform the classical motion model into a Port-controlled Hamiltonian motion model.Based on energy shaping and damping injection,a Port-controlled Hamiltonian controller is built to take into account the model uncertainty while maintaining the interconnection structure of the system model for the established open-loop model.Meanwhile,the asymptotic stability of the designed controller is demonstrated by using the passive property of the Port-controlled Hamiltonian control system,which ensures the accurate tracking of the navigator.It is also verified by simulation that the designed controller not only ensures its anti-disturbance but also can track the desired trajectory continuously and stably.(3)A velocity observer is also designed based on the idea of immersion and invariant manifold for the case that the state of the vehicle is unknowable under the condition that it is not equipped with velocity sensors.Firstly,due to the existence of inertial array in the vehicle system,the state space expressions need to be regularized in the process of applying the immersion and invariant manifold ideas,so the vehicle position-velocity state expressions are transformed into position-momentum form system equations.The definition of the expectation system observer is then carried out and a design epidemic surface is given,followed by the derivation of the observer generalized error Hamiltonian system.At the same time,a class of partial differential equations that can satisfy the immersion and invariance properties is defined,and a full-dimensional asymptotically stable velocity observer for the navigator can be derived.The stability of the designed observer can then be demonstrated based on the theory of nilpotency Finally,simulations are performed to verify the results,which show the effectiveness of the designed observer.