This paper designs an adaptive formation control system for unmanned underwater vehicles (UUVs) in the presence of unmeasurable states and environmental disturbance. To solve the problem of unmeasurable UUV states, a filtered high-gain observer (FHGO) is employed to estimate the states, despite measurement noise. Then, an adaptive control scheme is designed to achieve UUV formation collision avoidance. The radial basis function (RBF) is used to estimate the unknown disturbance. The stability of UUV formation with collision avoidance is proven by using the Lyapunov theorem. Numerical simulation is carried out to demonstrate that the proposed filtered high-gain observer is successful in estimating the states of UUVs. The control law can keep the UUV formation from collision with good performance.

In this paper, we propose a robust tracking control scheme for trajectory tracking of overactuated marine surface vessels subject to environmental disturbances and asymmetric time-varying full-state constraints. The proposed robust control scheme is based on the unified barrier function technique that converts the original constrained dynamic positioning system into an equivalent nonconstrained one. In contrast to barrier Lyapunov function-based methods, the unbreakable requirement on the constraints is less restrictive, and the resultant controller is much simpler in this paper. The effect of environmental disturbances is compensated by a double-layer adaptive sliding mode disturbance observer. On the basis of the proposed adaptive disturbance observer, unknown lumped uncertainty can be estimated in finite time without knowing the upper bounds of the derivative of the lumped uncertainty. Since the surface vessel is overactuated, a control allocation scheme is required to distribute the generalized force signal to the actuators. The enhanced redistributed pseudoinverse algorithm is employed to ensure that the generalized force can be redistributed among the redundant actuators. Lastly, a simulation study is carried out on a dynamic positioning ship to verify the effectiveness of the proposed control method.

A fault‐tolerant supervisory control method for dynamic positioning of ships with actuator failures and sensor failures is presented in this paper. Unlike the traditional fault detection and control, fault detection and fault‐tolerant controller are designed as a unit in this paper through a supervisor. By introducing a nonlinear estimation error and virtual controller, the sensor failures are separated from the actuator failures in the supervisory control system. It guarantees that the detectability property and matching property of the switched system are satisfied. Firstly, a new extended state observer is designed to match the models of different actuator failures. Secondly, by introducing a virtual controller, the detectability property of the switched system is guaranteed. Finally, a nonlinear estimation error operator is used in the designing of switching logic to guarantee stability of the closed‐loop system with sensor failures. When sensor failures and actuator failures occur, we show that all the states of the closed‐loop system are guaranteed to be bounded. The effectiveness of the fault‐tolerant control is verified by simulation experiments.