Motion Control Of Underwater Vehicle Research Articles

Maximum likelihood interval-varying recursive least squares identification for output-error autoregressive systems with scarce measurements

The identification problem of output-error autoregressive (OEAR) systems with scarce measurements is considered in this paper. In order to overcome the massive absence of outputs, an interval-varying recursive identification algorithm is proposed through changing the sampling interval and skipping the missing outputs. Based on the maximum likelihood principle, a maximum likelihood interval-varying recursive least squares algorithm is proposed. The effectiveness of the proposed algorithm is tested by a numerical simulation example, and an application example about the heading motion control of underwater vehicle.

Stability analyses on a towed underwater vehicle motion control system using a high‐gain observer

AbstractThis paper presents stability analyses on a towed underwater vehicle (TUV) motion control system using movable wings. The control method utilized is an output‐feedback controller based on linear state‐feedback control and a high‐gain observer. In order to analyze the closed‐loop stability of the system, the singular perturbation method is employed. Not only the asymptotic stability of the system is proved, but also an estimate of its region of attraction is derived. To describe a region of attraction, we propose a method by employing a hyper rhombus, which is quite suitable for quadratic Lyapunov functions. Further, to obtain a less conservative estimate, a state‐space‐scaling method is devised and its efficacy is evaluated by comparing with the conventional estimation method. Then, results of regulation simulations with various initial conditions are provided, which explores the consistency and gap between the theoretical estimate and the simulation results, and the robustness of the control system. Finally, a depth‐tracking control system via switching controllers is constructed according to the results of the stability analysis which investigates configuration of multiple equilibria with different depths and their regions of attraction, and demonstration simulation results are presented to illustrate the validity of the perspective given by the stability analysis.

Technology of cybernetic models’ creating for the synthesis and refinement of autonomous underwater vehicle motion control system controllers

The technology of cybernetic models’ creating for the synthesis and refinement of algorithms for controlling the autonomous underwater vehicle’s (AUV’s) motion is considered. The paper gives a description of the following sequence of actions performed at each stage of the cybernetic model development: dynamic model type and parameters identification, controller type selection, construction and analysis of the considered control loop block diagram, determination of the controller’s optimal parameters. The synthesis of heading, pitch and depth stabilization regulators for streamlined shape AUV during propulsion engines controlling is performed. The results of numerical modeling and research of the various factors influence on the quality of control are presented.

Deriving a six-dimensional mathematical model of an unmanned underwater vehicle motion control system with interval parameters

The paper is dedicated to a problem of mathematical modeling of a motion control system for unmanned underwater vehicle. The proposed model considers interval parametric uncertainty of underwater vehicle itself and water environment, nonlinearity of control object and actuator of the system and interaction between its control channels. In order to derive the model several objectives were accomplished: a mathematical model of underwater vehicle motion in a viscous fluid in all six degrees of freedom was derived; mathematical model of separate thruster and whole propulsion and steering system was derived; both model were linearized with the help of interval linearization method and, finally, a structure of the whole motion control system was determined. The model is applicable for simulation modeling of underwater vehicle motion and for analysis and synthesis of motion control systems in condition of interval parametric uncertainty.

Longitudinal motion control of underwater vehicle based on fast smooth second order sliding mode

By considering the influence of model uncertainty and external disturbance as well as combining theory of high order sliding mode with the recurrent hermite neural network (RHNN), this paper proposed a nonlinear robust control method for solving the longitudinal motion control problem of underwater vehicles. Based on the characteristics of multiple time scales, the longitudinal motion model was divided into inner and outer loops. The designed fast and smooth second order controller, which applied the discontinuous sign function on the derivative of the control law, was used in the outer loop. Then integration was performed to obtain the continuous sliding mode control law, which was applied to remove chattering and improve convergence rate. Furthermore, based on the controller of outer loop, the composite disturbance of the inner loop was effectively estimated using the combination between the fast smooth second order sliding mode controller and the RHNN disturbance observer. Therefore, the controller was effectively compensated, and the entire system’s stability in finite time was proved. The simulation results confirmed the promising performance and robustness of the proposed control method.

Synthesis of a PID-controller of a trim robust control system of an autonomous underwater vehicle

Autonomous underwater vehicles are often used for performing scientific, emergency or other types of missions under harsh conditions and environments, which can have non-stable, variable parameters. So, the problem of developing autonomous underwater vehicle motion control systems, capable of operating properly in random environments, is highly relevant. The paper is dedicated to the synthesis of a PID-controller of a trim robust control system, capable of keeping an underwater vehicle stable during a translation at different angles of attack. In order to synthesize the PID-controller, two problems were solved: a new method of synthesizing a robust controller was developed and a mathematical model of an underwater vehicle motion process was derived. The newly developed mathematical model structure is simpler than others due to acceptance of some of the system parameters as interval ones. The synthesis method is based on a system poles allocation approach and allows providing the necessary transient process quality in a considered system.

Path-Following Control of an AUV: Fully Actuated Versus Under-actuated Configuration

AbstractThe problem of motion control of underwater vehicles in both the fully actuated and under-actuated configurations is often confronted by the marine technology community. This paper presents a nonlinear control method for autonomous underwater vehicles (AUVs) traveling along a planned planar path in both actuation configurations. The common objectives of path-following control for both fully actuated and under-actuated vehicles are described, and the differences in the necessary path-following control designs are analyzed, showing that the side-slip angle of the vehicle plays an important role in the evolution of the dynamics of AUVs with different actuation configurations. Based on the presented analysis, nonlinear controllers for the two types of AUV configurations are proposed, and the inherent characteristics of under-actuation and full actuation are revealed by a dedicated analysis of numerical simulation paradigms, the results of which will be instrumental in guiding marine technology engineers in the practical design and control of AUVs.

Path following of underwater robots using Lagrange multipliers

This article proposes a framework for motion control of mechanical systems with application to underwater marine craft. Utilizing analytical mechanics, we establish a link between modeling and simulation of constrained multi-body systems in one hand and motion control of underwater vehicles on the other hand. The beauty of the presented approach consists in simplicity and physical interpretability, where imaginary dampers and springs introduce a deformable body and take care of motion of the vehicle. The proposed method is used to develop a novel path-following controller for UUVs.

Research on Motion Control of AUV with Hybrid Actuators

A switch function is presented to smooth control instructions and avoid system vibration during switch operating underwater vehicles with hybrid actuators. And a Modified S-plane Controller (MSC) is proposed by analyzing underwater vehicles dynamics and taking static force and coupling effects between the longitude velocity and other dimensions into account. Besides the advantages of S controller such as simple structure, MSC can solve the motion control of underwater vehicle at high speed which is difficult to control with S-plane controller. The stability of MSC is analyzed with Lyapunov function. Finally, MSC is applied to the motion control of an autonomous underwater vehicle controlled by rudders and thrusters. The feasibility of MSC is demonstrated by the results of velocity control, yaw control and depth control tests.

Design of Dynamic Control on Underwater Vehicle

Considering the effects in the gravity, buoyancy, thrust and hydrodynamic on the underwater vehicle, based on the perspective of the dynamic control, established a relatively complete dynamic model of underwater vehicle, analyzed and designed the control system on this base. The control system is consisted of two control loop. Dynamic compensation of the within control loop based on the dynamic characteristic of the vehicle, by the role of the within control loop, the vehicle became an easy to control and a decoupled linear system. Outer control loop achieved a negative feedback control through the use of proportional and differential item on the actual vehicle pose and the posture deviation expected. Adjusted by adjusting the parameter matrix Kd, Kpcan get the desired attenuation of the error, which can achieve precise motion control of underwater vehicles. Simulation results show that: the control model, in the paper, can be built for dynamic control of underwater vehicles, there is a strong anti-interference ability, can better realize the theory of time-varying trajectory tracking.

A Flexible Hingeless Control Surface Inspired by Aquatic Animals

A flexible hingeless control surface model was proposed for motion control of Underwater Vehicles (UVs), which is inspired by the flexible bending control surfaces of underwater creatures, such as fish and squid. Computational Fluid Dynamics (CFD) simulation demonstrates that, in comparison with the hinged or rigid control surface, the proposed flexible bending control surface can suppress the flow separation so as to improve the turning performance. A prototype of the flexible control surface was fabricated, in which Shape Memory Alloy (SMA) wires were selected as the actuators. The elastic energy storage and exchange mechanism was incorporated into the actuation of the control surface to improve the efficiency. Thermal analysis of SMA wires was performed to find proper actuating condition. Open-loop bending experiments were carried out. The results show that the proposed control surface can achieve the maximum bending angle of 104°. Moreover, the power and energy consumption under different pulse conditions were compared.

Synthesis of a system of automatic calculation of program signals for controlling motion of an underwater vehicle along a complex spatial trajectory

A new approach to accurate motion control of underwater vehicles is suggested. It consists in automatic calculation of program signals allowing the vehicle moving with variable speed along a spatial trajectory to pass separate trajectory segments as fast as possible. The desired speed of the underwater vehicle is calculated based on the maximum admissible deviation from the given trajectory and the norm of the dynamic error vector. Results of mathematical simulation substantiated workability and high efficiency of the proposed approach and the synthesized system of automatic calculation of program signals of accurate spatial motion of the underwater vehicle.

C27 導電性高分子を用いた生物模倣型アクチュエータの制御(OS11 海洋におけるシステムと制御2)

Precise motion control of underwater vehicles without mechanical noises is a technical issue on underwater observation. As a solution for the problem, we pay attentions to bio-mechanisms of underwater creatures, especially ribbon-like fins being used for attitude control. Bio-mechanisms of creatures are adapted to environment as a result of evolution. If the motor control mechanisms of the creatures can be introduced into underwater robots, there is a possibility that a high performance actuator will be realized. In this research, we have been trying to develop a biomimetic underwater actuator instead of screw propellers. As the material of a developing actuator, electroconductive polymer is used as an artificial muscle. We introduce the developing biomimetic actuator and the performance evaluation test of motion control experiments is discussed.

Motion control of underwater vehicle based on least disturbance BP algorithm

Up to now, some technology of neural networks are developed to solve the non-linearity of researched objects and to implement the adaptive control in many engineering fields, and some good results were achieved. Though it puts some questions over to design application structure with neural networks, it is really unknowable about the study mechanism of those. But, the importance of study ratio is widely realized by many scientists now, and some methods on the modification of that are provided. The main subject is how to improve the stability and how to increase the convergent rate of networks by defining a good form of the study ratio. Here a new algorithm named LDBP (least disturbance BP algorithm) is proposed to calculate the ratio online according to the output errors, the weights of network and the input values. The algorithm is applied to the control of an autonomous underwater vehicle designed by HEU. The experimental results show that the algorithm has good performance and the controller designed based on it is fine.