Underactuated Unmanned Underwater Vehicle Research Articles

Trajectory Tracking Control of Unmanned Underwater Vehicle Based on Projected Perpendicular Guidance Method with Disturbance Observer

Unmanned underwater vehicles (UUVs) possess impressive maneuverability and versatility, but controlling them during trajectory tracking can be challenging due to their susceptibility to external disturbances and perturbations in their model parameters. Additionally, the UUV has four degrees of freedom underwater, but only three control inputs, making it a typical underactuated system. To address these issues, this paper introduces a novel optimize sliding mode control (OPSMC) algorithm grounded in projected perpendicular guidance (PPG). The PPG algorithm transforms the three-degree-of-freedom path trajectory control into two-degree-of-freedom heading tracking control and surge velocity tracking control by designing virtual posture angles. Optimized sliding mode control, based on sliding mode control, improves control precision and reduces control input chattering by constructing optimization functions for control inputs. During trajectory tracking, UUVs are susceptible to external environmental disturbances and perturbations in system model parameters. Disturbance observers are employed to estimate these disturbances and perturbations. Finally, MATLAB/Simulink is used for numerical simulation experiments. The simulation results demonstrate that the PPG algorithm effectively enables underactuated UUVs to achieve trajectory tracking control. The designed optimized sliding mode controller and disturbance observer enhance the control precision and robustness of the system.

A novel method for underactuated UUV tracking unknown contour based on forward-looking sonar

Tracking unknown contour is an essential problem for automated operations of Unmanned Underwater Vehicle (UUV). Applications such as harbor surveillance, island survey, and obstacle avoidance require UUV with the ability to track the contours of unknown marine structures. The absence of a priori information poses a great challenge in solving such problems. Most existing approaches follow the sense-act pattern by designing elaborate control laws to solve the problems under specific configurations. However, they demand much complexity to implement and lack generalizability in unstructured environments. This paper presents a novel unknown contour tracking method based on the sense-plan-act formulation and focuses primarily on the first two processes to make results applicable to conventional controllers. In terms of perception, forward-looking sonar (FLS) is used as the main device of data collection and a probabilistic perception model and a rolling occupancy grid map construction method based on this model are introduced. For planning, it is assumed that the UUV is underactuated and maneuvers in a 2D plane. Considering multiple tracking metrics, the problem is described as a multi-objective optimization problem and an emerging swarm intelligence algorithm is chosen as the solver. Notably, a contour prediction mechanism and a real-time risk assessment and replanning strategy are designed to ensure the continuity and navigational safety of the tracking process, respectively. Results demonstrate the effectiveness of the proposed method with contours extracted from real harbor and island.

Depth control of an unmanned underwater vehicle based on robust inversion and sliding mode variable structure control

This paper addresses the depth control problem of an underactuated Unmanned Underwater Vehicle (UUV) subject to model uncertainties and ocean current interference. A robust inversion sliding mode variable structure control method is proposed. First, a vertical-plane UUV depth control model is established. Then, the inversion control method is combined with the sliding mode variable structure control method to devise an inversion sliding mode control algorithm. In order to further improve the control system’s robustness against external environmental interference, a robust control methodology is introduced for the design of the depth controller. Simulation results demonstrate that the designed controller effectively addresses the issues of model uncertainties and ocean current interference, thereby enhancing the UUV’s depth control accuracy.

Reinforcement Learning-based path tracking for underactuated UUV under intermittent communication

This paper studies the path control of a six-degree-of-freedom underactuated Unmanned Underwater Vehicle (UUV) under limited communication conditions. Considering the large number of coupling between six-degree-of-freedom underactuated UUV of unknown dynamic models, traditional model-based control methods are difficult to effectively solve the three-dimensional path control problem. A self-attention based soft actor and critic (A-SAC) algorithm is designed to learn effective control policy from random paths. The problem of limited target acquisition by UUV in the actual underwater environment is effectively overcome, which is mainly caused by the inability of UUV to consistently receive information about their expected path. A new state space is designed and a self-attention mechanism is introduced to improve the efficiency of using discontinuous path information. Furthermore, the validation experiment compares classical Reinforcement Learning methods such as DDPG, PPO, and etc. Compared to other existing methods, the proposed A-SAC algorithm can more quickly and effectively learn the path control policy for a six-degree-of-freedom UUV that operates in a complex environment.

Model-free finite-time formation containment control of underactuated UUVs subject to input delays and unknown interaction information

This paper put forwards a model-free adaptive neural finite-time formation-containment (FC) control scheme for time-delayed underactuated unmanned underwater vehicles (UUVs) with unknown dynamic models and some interaction information under switching topologies. The UUVs are steered by multiple child leaders moving along with a root leader, where all leaders are virtual and defined by a new generalized dynamic. A novel autoregressive model-based state predictor is created for each UUV, which can construct future motion states online relying on current and stored states. Considering the containment layer, a finite-time super-twisting observer is used to recover the unavailable interaction information. Moreover, observer-based finite-time kinematic guidance laws employing only 3D positions of the neighboring UUVs are devised, together with protocols for completing formation in finite time. Aiming to accurately identify unknown dynamics and control gains simultaneously, estimator-based adaptive neural networks are introduced exploiting both historical and real-time data. Finally, model-free anti-disturbance finite-time kinetic control protocols are designed based on the data-driven adaptive neural networks and nonlinear tracking differentiators. It is proven that all signals of the closed-loop FC system are bounded, the deployed FC tracking can be achieved in finite time. Simulation results verify the feasibility and superiority of the proposed FC control scheme.

Single dimension-based fuzzy sliding mode control design for the stabilisation of underactuated unmanned underwater vehicle

Single dimension-based fuzzy sliding mode control design for the stabilisation of underactuated unmanned underwater vehicle

Single dimension based fuzzy sliding mode control design for the stabilisation of underactuated unmanned underwater vehicle

Single dimension based fuzzy sliding mode control design for the stabilisation of underactuated unmanned underwater vehicle

Finite-time sideslip observer-based synchronized path-following control of multiple unmanned underwater vehicles

A synchronized path-following control scheme for a cluster of networked unmanned underwater vehicles (UUVs) suffering from unknown dynamics and unknown sideslip angles is proposed in this paper. On the basis of UUV kinematics model, the unknown sideslip angles are successfully identified using finite-time observers, thereby ensuring high accurate path-following performance. By virtue of individual path-following and consensus information, the coordinated light-of-sight guidance and the path update protocol are employed, respectively, which provide sufficient technology support for desired formation pattern. Simultaneously, an adaptive approximation is incorporated into the distributed dynamics controllers, where the lumped unknowns involving modeling uncertainties and time-varying ocean currents are estimated accurately, thereby enhancing the formation system anti-disturbance performance. It is proven that, with the proposed scheme, all vehicles can track the multiple parametric paths synchronously and the entire closed-loop system is globally asymptotically stable. Finally, simulation results for coordinated path-following of four underactuated UUVs are exhibited and discussed.

Globally finite-time stable three-dimensional trajectory-tracking control of underactuated UUVs

In this paper, the subject of the spatial trajectory-tracking control for underactuated unmanned underwater vehicles (UUVs) is addressed in the presence of model parameter perturbation and unknown ocean currents. The spatial trajectory-tracking guidance is established based on the dynamic virtual vehicle method, which continuously computes the desired motion states of an UUV to be used by the motion control system. The globally finite-time control strategy is proposed based on the proportional-integral-derivative sliding mode control (PID-SMC), which globally stabilizes all trajectory-tracking errors in the finite time. By all simulation results showing, this trajectory-tracking control strategy can drive the underactuated UUV with ±20% model parameter perturbation to track the predefined desired trajectory accurately in the three-dimensional space. All simulation results fully indicate that the tracking controller offer highly flexibility and strongly robustness in connection with the model parameters uncertainties.

Trajectory Tracking Control of UUV Based on Backstepping Sliding Mode With Fuzzy Switching Gain in Diving Plane

Considering the actual situation of time-varying interference in the underwater environment, a trajectory tracking control method for an underactuated Unmanned Underwater Vehicle (UUV) underwater exploration based on backstepping sliding mode with fuzzy switching gain is designed in this paper. Firstly, the motion equations of UUV in diving plane are given. Secondly, the virtual control variable is designed to replace the pitch angle to avoid the singular value phenomenon. Combining with the backstepping technique, the fuzzy switching sliding mode controller is proposed. Thirdly, in order to decrease the chattering phenomenon of sliding mode control, the fuzzy rule of sliding mode gain is designed. Fourthly, based on Lyapunov theory and comparison principle, the global asymptotic stability of UUV closed-loop tracking error system is proved. Finally, the simulation results demonstrate the effectiveness and robustness of the proposed controller.

Double-Loop Structure Integral Sliding Mode Control for UUV Trajectory Tracking

To solve the problem of trajectory tracking control for the underactuated unmanned underwater vehicle (UUV) in external current disturbance, a back-stepping sliding mode control method with double-loop structure is proposed in this paper. The outer-loop controller constructs the position error sliding surface through desired position error, obtains the kinematics control law by combining with power reaching law, and gets the error of virtual velocity after completing the design of trajectory tracking kinematics controller. The inner-loop controller constructs the sliding surface of longitudinal, horizontal, and vertical velocity error, respectively, with the help of the UUV speed error. Also, the trajectory tracking dynamic controller is designed by combining with the exponential reaching law, where the control moment is almost chattering-free. The stability of the double-loop control system is proved by combining with the Lyapunov stability theory. Finally, the simulation experiments verify the high effectiveness of the algorithm.

Consensus Path-following Control of Multiple Underactuated Unmanned Underwater Vehicles

This work mainly studies the problem of how to steer a group of underactuated unmanned underwater vehicles UUVs to specified paths coordinately. The algorithm proposed consists of a single path-following strategy and a path parameter consensus tracking strategy. In the context of single path following, we describe the path to be followed by an arbitrary scalar, then by using Lyapunov and backstepping theories, a single path-following strategy was derived to drive each UUV move to the predefined path asymptotically. In the coordinated level, we focus on the coordination for the scalar parameters. In particular, we show that all the path parameters can track with a virtual reference leader who is a neighbor of only a subset of following UUVs with local interactions. The stability of the closed system was proved and analyzed theoretically. The validity of the algorithm proposed is supported by simulation results.

Energy-based guidance of an underactuated unmanned underwater vehicle on a helical trajectory

This paper presents a motion control system for guidance of an underactuated Unmanned Underwater Vehicle (UUV) on a helical trajectory. The control strategy is developed using Port-Hamiltonian theory and interconnection and damping assignment passivity-based control. Using energy routing, the trajectory of a virtual fully actuated plant is guided onto a vector field. A tracking controller is then used that commands the underactuated plant to follow the velocity of the virtual plant. An integral control is inserted between the two control layers, which adds robustness and disturbance rejection to the design.

Globally finite-time stable tracking control of underactuated UUVs

This paper addresses the problem of trajectory tracking control for underactuated unmanned underwater vehicles (UUVs) with model parameter perturbation and constant unknown current in the horizontal plane. The globally finite-time tracking control strategy is adopted driving an UUV to track a predefined trajectory. Firstly, the horizontal trajectory tracking guidance laws are established by the virtual vehicle method, where the tracking error equations are derived. Secondly, the kinematic controllers are designed with equivalent control of the proportional-integral-derivative sliding mode control (PID-SMC). Thirdly, two dynamic controllers, including a speed controller and a steering controller, are designed by resorting to a first-order sliding mode surface and a second-order one, respectively. It is well proved that the proposed strategy can guarantee global convergence of all tracking errors within finite time. Simulations show that the control laws can achieve strongly robust and preferably control performance for the horizontal trajectory tracking control in the presence of the mode parameter perturbation and constant unknown current.

Dynamical sliding mode control for the trajectory tracking of underactuated unmanned underwater vehicles

This paper proposes a novel adaptive dynamical sliding mode control based methodology to design control algorithms for the trajectory tracking of underactuated unmanned underwater vehicles (UUVs). The main advantage of the approach is that the combination of backstepping and sliding mode control enhances the robustness of an UUV in the presence of systematical uncertainty and environmental disturbances. The position and attitude dynamical equations of an underactuated UUV are first represented and analyzed using coordinate transformation with the aid of backstepping technique. Subsequently, the output feedback problem is tackled by employing adaptive sliding mode control to estimate the systematical uncertain states required by the stable velocity tracking controller. The final controlled system can be proved to be globally asymptotically stable based on Lyapunov stability theory. Simulations performed on an underactuated UUV demonstrate the effectiveness of the proposed method.

Trajectory tracking control of an underactuated unmanned underwater vehicle synchronously following mother submarine without velocity measurement

This article addresses the trajectory tracking control of underactuated unmanned underwater vehicles, where the control structure is designed to synchronously follow the mother submarine with only available position information. The controller is derived using the virtual guidance strategy and backstepping-based design techniques. The virtual guidance system is first constructed to eliminate the measurement of the mother submarine’s velocity and dynamics. The convergence and effectiveness of the virtual guidance system are proven using Lyapunov stability theory. In addition, to enhance the robustness of the underactuated vehicle against the unmodeled dynamics and unknown disturbances from the environment, radial basis function neural networks are finally used to approximate the nonlinear uncertainties. Under the proposed control, semiglobal uniform boundedness of the closed-loop system is guaranteed for adequate choices of the controller gains. A simulation example is included to demonstrate the effectiveness and robustness of the approaches suggested.

Guidance of AUVs for Autonomous Underwater Inspection

Abstract In this paper, a task-based online path-planning and guidance system of underactuated unmanned underwater vehicles (UUVs) for inspection of underwater infrastructure is described. Whether there are harbor submerged structures, cables, pipes, hydro-technical works, they all need to be checked in relation to structural deterioration specific potential problems such as scour, erosion, and accelerated local corrosion problems. At the highest level, the mission controller handles different event types, permitting also the execution of mission tasks. The online path-planning module generates a set of waypoints based on an environmental perception module for the AUV to follow the target object with a constant distance. The guidance method actually controls the vehicle to follow the waypoints, assuming the relative position and attitude of the vehicle is precisely estimated in real-time. By combining these methods, an AUV can perform fully autonomous inspection of underwater structures. The system was evaluated with success for several harbor and pipeline inspection scenarios in a test basin and sea trials.

Dynamic Surface and Active Disturbance Rejection Control for Path Following of an Underactuated UUV

This paper addresses the problem of accurate path following control for an underactuated unmanned underwater vehicle (UUV) in the horizontal plane. For an underactuated UUV, the line-of-sight (LOS) guidance method is adopted to map 2D reference trajectory into a desired orientation, and through the tracking of heading to achieve path following, where the sideslip is introduced to modify the desired orientation. In this paper, we propose a method called dynamic surface and active disturbance rejection control (DS-ADRC) to solve the path following control problem. This controller can effectively avoid the phenomenon of explosion of terms in the conventional backstepping method, reduce the dependence on the UUV controller mathematical model, and enhance the antijamming ability. Simulation is carried out to verify the effectiveness of the proposed control method for an underactuated UUV. The results show that, even for this controller with disturbance, the cross-track error of UUV is gradually converged to zero and has some certain robustness.