Bruno Jouvencel

Robust Nonlinear Path-Following Control of an AUV

This paper develops a robust nonlinear controller that asymptotically drives the dynamic model of an autonomous underwater vehicle (AUV) onto a predefined path at a constant forward speed. A kinematic controller is first derived, and extended to cope with vehicle dynamics by resorting to backstepping and Lyapunov-based techniques. Robustness to vehicle parameter uncertainty is addressed by incorporating a hybrid parameter adaptation scheme. The resulting nonlinear adaptive control system is formally shown and it yields asymptotic convergence of the vehicle to the path. Simulations illustrate the performance of the derived controller .

Smooth transition of AUV motion control: From fully-actuated to under-actuated configuration

This paper addresses the problem of steering autonomous underwater vehicle (AUV) along a desired horizontal path throughout the full-range low-speed and high-speed profiles, experiencing both fully-actuated and under-actuated configurations. First, a nonlinear controller adopting Lyapunov’s direct method and backstepping technique is proposed for under-actuated AUV, based on the Line-of-Sight guidance built in a moving Frenet–Serret frame. And then, the controller is adapted to fully-actuated AUV except that the control computation for the evolution of the side-slip angle is different from the case of under-actuated one. Hence, both the fully-actuated and under-actuated configurations are under the same control framework, which enables a smooth continuous transition between two configurations in a synthesized controller. Finally, simulation results illustrate the performance of the proposed control design, where the varied control efforts in the sway direction clearly show the transitions from fully-actuated to under-actuated configuration.

Homing by acoustic ranging to a single beacon

Homing and docking capabilities are essential in many autonomous underwater vehicle (AUV) applications. The paper tackles the homing problem, leaving aside the actual docking of the vehicle. Homing is often performed by means of acoustic sensors providing the bearing of the beacon to be reached in the vehicle frame. This measurement, combined with the vehicles heading, is used directly to steer the AUV towards the goal. The algorithm described in the paper only uses acoustic range measurements to the beacon. The difficulties of this approach are due to the fact that a single range measurement does not completely constrain the beacons position in the vehicle frame nor does it define the direction to follow. In addition, range measurements are noisy and sometimes spurious, and underwater currents affect dead-reckoning measurements. The AUV has then to maneuver, filter the range measurements and estimate the underwater current in order to maintain an estimation of the beacons position. The homing procedure consists of obtaining an initial estimate of the beacons position and of the underwater current components by appropriate maneuvers. The initial estimates are further refined during the actual displacement towards the beacon by means of a Kalman filter.

Coordinated Formation Control of Multiple Autonomous Underwater Vehicles for Pipeline Inspection

This paper addresses the control problem of inspecting underwater pipeline on the seabed, with coordinated multiple autonomous underwater vehicles in a formation. Based on the leader-follower strategy, the dedicated nonlinear path following controller is rigorously built on Lyapunov-based design, driving a fleet of vehicles onto assigned parallel paths elevated and offset from the underwater pipeline, while keeping a triangle formation to capture complete 3D images for inspection. Due to the spatial-temporal decoupling characteristics of individual path following controller, the velocities of the followers can be adapted in the coordinated control level, only relying on the information of generalized along-path length from the leader, in order to build the desired formation. Thus, the communication variable broadcast from the leader is kept to a minimum, which is feasible under the severely constraints of acoustic communication bandwidth. Simulation results illustrate the efficiency of coordinated formation controller proposed for underwater pipeline inspection.

Homing and navigation using one transponder for AUV, postprocessing comparisons results with long base-line navigation

Homing and navigation capabilities are essential in many autonomous underwater vehicle (AUV) applications. The paper presents both problems with respect to a single beacon. The difficulties of this approach are due to the fact that a single range measurement does not completely constrain the beacons position in the vehicle frame. In order to triangulate his position, the AUV needs to maneuver while measuring its displacements between ranges. In addition, range measurements are noisy and sometimes spurious, speed bias and underwater currents affect dead-reckoning measurements. Homing and navigation procedures are the same beginning. In a first time, we have an initialization phase which is necessary to obtain an initial estimate of the vehicles absolute position and of the disturbances affecting the quality of the dead reckoned displacements. These initials estimates are refined during the actual displacement towards the beacon by means of a Kalman filter. Two kinds of navigation are used so as to maximize the information matrix and to maintain an accurate absolute position. We present also postprocessing results and a comparison with LBL navigation.

Synchronized path following control of multiple homogenous underactuated AUVs

This paper addresses the problem of synchronized path following of multiple homogenous underactuated autonomous underwater vehicles (AUVs). The dedicated control laws are categorized into two envelopes: One is steering individual underwater vehicle to track along predefined path, and the other is ensuring tracked paths of multiple vehicles to be synchronized, by means of decentralized speed adaption under the constraints of multi-vehicle communication topology. With these two tasks formulation, geometric path following is built on Lyapunov theory and backstepping techniques, while injecting helmsman behavior into classic individual path following control. Synchronization of path parameters are reached by using a mixture of tools from linear algebra, graph theory and nonlinear control theory. A simple but effective control design on direct inter-vehicle speed adaption with minimized communication variables, enables the multi-AUV systems to be synchronized and stabilized into an invariant manifold, and all speeds converge to desired assignments as a byproduct. Simulation results illustrate the performance of the synchronized path following control laws proposed.

Using a high order sliding modes for diving control a torpedo autonomous underwater vehicle

In this paper, a high order sliding modes control (HOSMC) is used to control TAIPAN, a torpedo shaped AUV from LIRMM, France. The implementation of a second order sliding mode controller in this system is the main contribution of this work. Sliding mode control (SMC) is adequate for controlling AUVs, since it offers robustness in the presence of uncertainties parameters and environmental disturbances, however the main drawback is the chattering effects that stimulates high frequency vibration that can damage the actuators. HOSMC control preserves the properties of standard SMC and removes the chattering effects. The design of proportional derived (PD), SMC and HOSMC controller for control TAIPAN depth are described. A comparative study between the control laws is presented. The nonlinear hydrodynamic model of TAIPAN is used in the numerical simulations. Simulation results, that enlighten performance of the automatic controllers are shown.

Simulation results, post-processing experimentations and comparisons results for navigation, homing and multiple vehicles operations with a new positioning method using on transponder

Homing and navigation capabilities are essential for many autonomous underwater vehicle (AUV) applications. This paper presents both problems with respect to a single beacon and an extension of the method for multiple AUV operation using relative location. The difficulties of this approach are due to the fact that a single range measurement does not completely constrain the beacons position in the vehicle frame. In order to triangulate his position, the AUV needs to maneuver while measuring its displacements between ranges. In addition, range measurements are noisy and sometimes spurious, speed bias and underwater currents affect dead-reckoning measurements. All operation need to have the same beginning. An initialization phase is necessary to obtain an initial estimate of the vehicles location with respect to a fixed or moving beacon. These initial estimates are refined during the actual displacement towards the beacon by means of a Kalman filter. Two kinds of navigation are used so as to maximize the information matrix and to maintain an accurate absolute position. We also present post-processing results in comparison with LBL navigation and mission experimentation post-processing treatment. And then we applied our method for two vehicles operation.

A robust control algorithm for AUV: based on a High Order Sliding Mode

This paper proposes to introduce new control law algorithm based on high order sliding modes (HOSM) for dive control of the autonomous underwater vehicle (AUV) Taipan. A comparison with classical sliding mode (SM) is carried out as well. These control techniques are based on second order sliding modes. High order methods allow overcoming the chattering effect by removing the discontinuity of the control vector. We show that these high order controllers hold the properties of classical SM control laws and remove chattering problem. Another part of this paper is dedicated to compare SM vs. HOSM in Matlab simulations. These results underline the robustness of the HOSM at last.

Path tracking: Combined path following and trajectory tracking for autonomous underwater vehicles

This paper proposes a novel control strategy for autonomous underwater vehicles (AUVs), named as path tracking, which combines the conventional path following and trajectory tracking control in order to achieve smooth spatial convergence and tight temporal performance as well. This idea is inspired by the previous work of Hindman [1] and Encarnacao [2], however, the path tracking design herein goes from path following to trajectory tracking, which indeed is an inverse way from the previous solutions so that the complex projection algorithm resulting in a local stability is avoided. A kinematics controller is first derived by using Lyapunov direct method where a virtual path parameter is introduced to bring an extra control degree of freedom, and then it is extended to the dynamics of AUVs based on backstepping technique. The resulting nonlinear control design is formally shown and it yields global asymptotic convergence of the AUV to the path. Finally, simulation results illustrate the efficiency of the path tracking control design for AUVs.