Control Of Underactuated Underwater Vehicles Research Articles

Distributed Neurodynamics-Based Backstepping Optimal Control for Robust Constrained Consensus of Underactuated Underwater Vehicles Fleet.

Robust constrained formation tracking control of underactuated underwater vehicles (UUVs) fleet in 3-D space is a challenging but practical problem. To address this problem, this article develops a novel consensus-based optimal coordination protocol and a robust controller, which adopts a hierarchical architecture. On the top layer, the spherical coordinate transform is introduced to tackle the nonholonomic constraint, and then a distributed optimal motion coordination strategy is developed. As a result, the optimal formation tracking of UUVs fleet can be achieved, and the constraints are fulfilled. To realize the generated optimal commands better and, meanwhile, deal with the underactuation, at the lower-level control loop a neurodynamics-based robust backstepping controller is designed, and in particular, the issue of "explosion of terms" appearing in conventional backstepping-based controllers is avoided and control activities are improved. The stability of the overall UUVs formation system is established to ensure that all the states of the UUVs are uniformly ultimately bounded in the presence of unknown disturbances. Finally, extensive simulation comparisons are made to illustrate the superiority and effectiveness of the derived optimal formation tracking protocol.

Adaptive fixed-time containment control of uncertain underactuated underwater vehicles under dynamic event-driven mechanism

This paper presents a dynamic event-driven fixed-time design strategy for the three-dimensional containment control of underactuated underwater vehicles under a directed topology. Our main contribution is the development of a novel error transformation approach based on adaptive multi-leader estimation to address the fixed-time containment (FTC) control problem in the presence of underactuation input and unknown leaders’ velocity. An adaptive FTC control law using stabilizing auxiliary variables and nonlinear filters is constructed based on event-driven conditions. The dynamic thresholds, which depend on containment errors, are presented to efficiently reduce communication resources required for implementing the FTC controller. According to Lyapunov theory, it is shown that the trajectories of the followers converge to the convex hull spanned by multiple leader signals within a fixed time while ensuring the avoidance of the Zeno phenomenon. Finally, the effectiveness of the suggested control approach is verified through simulation results.

Assessing the feasibility of underwater vehicle controllers in underactuated hovercrafts via simulations

The paper presents a comparison of several selected trajectory tracking controllers used for an underactuated hovercraft. The aim of the study is to check if algorithms that have proved to be effective for another class of vehicles can be adapted to control a hovercraft. In order to compare the effectiveness of the controllers, one that is exclusively designed to control the hovercraft and three others that are suitable for the control of underactuated underwater vehicles were examined. This study also proposes a methodology for simulation analysis of control algorithms. The initial simulation tests demonstrated on the 3-DOF hovercraft model show the results that can be obtained by using each control algorithm under the proposed assumptions.

Spatial target path following and coordinated control of multiple UUVs

The coordination control of multiple Underactuated Underwater Vehicles (UUVs) moving in three dimensional space is investigated in this paper. The coordinated path following control task is decomposed into two sub tasks, that is, path following control and coordination control. In the spatial curve path following control task, path following error dynamics is build in the Serret-Frenet coordinate frame. The virtual reference object can be chosen freely on the desired spatial path. Considering the speed of the UUV, the line-of-sight navigation is introduced to help the path following errors quickly converge to zero. In the coordination control sub task, the communication topology of multiple UUVs is described by the graph theory. The speed of each UUV is adjusted to achieve the coordination. The path following system and the coordination control system are viewed as the feedback connection system. Input-to-state stable of the coordinated path following system can be proved by small gain theorem. The simulation experiments can further demonstrate the good performance of the control method.

Underactuated tracking control of underwater vehicles using control moment gyros

This article studies the trajectory tracking control of underactuated underwater vehicles using control moment gyros through a biologically inspired approach based on homeomorphism transformation and Lyapunov functions in the horizontal plane. First, a series of assumptions and simplifications need to be made to build the kinematic and dynamic equations of the underwater vehicle under a single-frame pyramid configuration structured with four control moment gyros. Second, the error dynamics analysis of the submarine based on the control moment gyros is derived from the equations, and a tracking control algorithm is proposed to demonstrate the feasibility and stabilization of this tracking control scheme from theoretical analysis. Finally, the numerical simulation results are given for verifying the effectiveness and feasibility of the rendered control law.

Adaptive fuzzy inverse trajectory tracking control of underactuated underwater vehicle with uncertainties

An independent adaptive fuzzy control system of nominal dynamics and uncertain parts is proposed to control an underactuated underwater vehicle with uncertainties based on computed-torque controller. A type of fuzzy inverse trajectory compensator as a nonlinear filter at input trajectory level outside the control loop is developed to compensate for uncertainties by modifying the desired trajectory outside the control loop and to address the issue of unavailable normalising factor. Trajectory tracking performances of the proposed control technique and of the computed-torque controller are compared. The proposed control scheme is simulated, and its efficiency is validated using numerical simulations of a 3-DOF underactuated underwater vehicle. Results confirm that the adaptive fuzzy compensator at the input trajectory level offers better trajectory tracking performances and easier practical implementation than other fuzzy compensation techniques at joint torque level.

AUV Robust Guidance Control

The control of under-actuated underwater vehicles with coupled dynamics is a research of major interest, not only but mainly due to the large number of applications in the offshore industry. In a former work, authors developed a controller exhibiting desired robustness features, which unfortunately presented a poor performance in tracking activities. To tackle this problem, a two degree of freedom robust controller using an ℋ∞ mixed sensitivity approach was developed and guidance rules were added to face the impossibility of a straight control of position variables within the used optimal approach. Guidance was accomplished using a Line of Sight (LOS) for horizontal motions and a Fuzzy Logic rule for vertical motions. Three cases of the tracking were simulated, its results validated clearly the good conjunction of the robust control and guidance approaches used here.

ROBUST CONTROL FOR UNDERWATER VEHICLE GUIDANCE

Nowadays the control of under-actuated underwater vehicles with coupled dynamics is a research of major interest, not only but mainly due to the large number of applications in the offshore industry. In a former work, authors developed a controller exhibiting desired robustness features, which unfortunately presented a poor performance in tracking activities. To tackle this problem, a two degree of freedom robust controller using an H∞ mixed sensitivity approach as before was then developed. A Light of Sight (LOS) guidance control law was also added to face the impossibility of a straight control of position variables within the used optimal approach. Simulation results of an Underwater vehicle with six degree of freedom using the centralized controller show now strong robustness and a very good performance.