Eicher Low

Robust and decoupled cascaded control system of underwater robotic vehicle for stabilization and pipeline tracking

The current paper proposes a robust and decoupled cascaded control system with output feedback control for simultaneous stabilization and pipeline tracking of a remotely operated vehicle (ROV) under hydrodynamic uncertainties. One of the ROV applications on the simultaneous stabilization and tracking was global output feedback with backstepping method on an ODIN ROV. However, the controller design becomes complex, as partial differential equations are required in the backstepping control law and the ROVs is inherently non-linear, highly coupled in motion, unsymmetrical in vehicle design, and vulnerable to hydrodynamic uncertainties. Compared with the backstepping control and other controllers, the computer simulation shows that the proposed method is simpler and performed better in time domain response and other performance measures such as robustness and stability.

A Control Module Scheme for an Underactuated Underwater Robotic Vehicle

Despite major advances in Autonomous Underwater Vehicle design, the manually operated Underwater Vehicle (ROV) is still very much the industry workhorse. Current technologies are being used to reduce the stress of direct task operations by providing autonomy and to improve efficiency. This paper presents a design of a control module subsystem for a VE tele-operated ROV system. It discusses the design and implementation of the control module. Using modelling, simulation and experiments, the vehicle model and its parameters have been identified. These are used in the analysis and design of closed loop stabilising controllers for station keeping. As the vehicle has fewer actuators than possible degrees of freedom, it is necessary to limit the controllable degrees of freedom. These variables are eventually selected based on the inherent vehicle dynamics. Using the Lyapunov direct method, appropriate stabilising controllers have been designed. The station-keeping mode controller has PID structure and its gain values are designed using a non-linear optimising approach. Simulation and swimming pool tests for the heave and yaw directions have shown that the control module is able to provide reasonable depth and heading station keeping.

A study of the control of an underactuated underwater robotic vehicle

Underwater robotic vehicles (URVs), generally, consist of two main classes, namely the remotely operated vehicles (ROVs) and the autonomous underwater vehicles (AUVs). In this paper, a simplified model of a thruster and a general equation of rigid body motion for an underactuated ROV are presented. Then the nonlinear and coupling effects on the ROV, from its shape and design, are derived and presented. Lastly, the steady-state nonlinear behaviour of the thrusters observed are used to design and develop a simple PID controller. Simulation results obtained demonstrated the capability of the controller in the regulating of the desired amount of thrust while maintaining a relatively small degree of steady-state error.

A Unified Pilot Training and Control System for Underwater Robotic Vehicles (URV)

This paper introduces the work done to improve on a sophisticated Underwater Robotic Vehicle (URV) inspection and repair system for submerged structures. It is undertaken as part of a research programme grant to pursue research and development of technologies and systems for the advancement of knowledge and for possible commercial exploitation relevant to the oil and gas industry. In particular, the paper focuses on the development of a unified pilot training and controls system that incorporates an advance man–machine interface for improving operator dexterity. Few formalised training procedures exist for URV pilots. In spite of the high cost, most URV pilots receive their training on-the-job. Training simulators can be viewed as a viable solution to this problem. Some attention has been made to address this problem. Notably are efforts by Imetrix URV-Mentor system, which focuses on VE simulation and on-line tutoring. Simulators, however, represents additional costs and in some ways lacks the realism of working on the real system. In the R2C the researchers proposed a novel simulator configuration. We have developed a dual-purpose topside control system configuration that can be used for training as well as for on-line operation of an actual URV. In the simulator configuration, the physical URV is replaced by a simulator module, which accepts actual commands from the control system and responds with a simulated URV status, using a dynamic model of the URV. The simulator module behaves much like the actual URV accepting commands and responds with status information. The advantage of such a system is perceived to be lower system cost as well as a more realistic testing and simulation of the relevant processes.

Development and improvement of an underactuated underwater robotic vehicle

This paper is a compilation of studies of the development and improvement of an underactuated remotely operated vehicle (ROV) - RRC ROV II. The development of the RRC ROV II is based largely on the first generation vehicle - RRC ROV I. RRC ROV II is comparatively larger in size and capacity, thus allowing the inclusion of better and more intelligent control. In this paper, the problems regulating such an underactuated ROV are addressed by designing a new control algorithm, so as to control the vehicle motions using only four actuators. In the initial part of the paper, models for the thrusters are presented, followed by the controller for the ROV. The simulated and experimental results of the controllers for RRC ROV II, using Matlabs Simulink, are also presented in comparison with the RRC ROV I.

Control of an underactuated remotely operated underwater vehicle

Abstract In this paper, a steady state model of a thruster and a general equation of rigid-body motion for an underwater robotic vehicle (URV) is presented. By means of modelling, simulation and experiments, the model parameters have been identified. These are used in the analysis and design of closed-loop stabilizing controllers for two control modes: manual cruise and station keeping. Since the URV under study has fewer actuators than possible degrees of freedom, it is necessary to limit the controllable degrees of freedom. These variables are eventually selected based on the inherent vehicle dynamics. Using the Lyapunov direct method, which has been shown to be appropriate for such non-linear systems, appropriate stabilizing controllers have been designed. The manual cruise mode controller is non-linear and would result in chattering in the thruster outputs, but simulations show that the desired results can be achieved. The station-keeping mode controller has a proportional-integral-derivative (PID) structure and its gain values are designed using a non-linear optimizing approach. Simulation and swimming pool tests for the heave and yaw directions have shown that such a controller is possible.

A Cascaded Nonlinear Heading Control with Thrust Allocation: An Application on an Underactuated Remotely Operated Vehicle

In this paper, we propose a new pipeline tracking control of an underactuated remotely operated vehicle (ROV) based on a thruster allocation and a nonlinear PD heading control for inner and outer loops respectively. The thruster allocation control without constraint uses the vehicles velocity feedback to detect the change in thrust required for the thrusters used in ROVs maneuvering. Generalized ROV models for decoupled horizontal and vertical plane motions are derived that based on small roll and pitch angles that are self-stabilizing during operations. When compared with the Proportional-Derivative (PD) controller for all motions, the proposed cascaded controller is proven to render the tracking error dynamic globally k-exponentially stable with a lower control effort needed. Computer simulations are performed on these controllers and shown to be robust against parametric uncertainty

DESIGN ANALYSIS OF THE PROPULSION AND CONTROL SYSTEM OF AN UNDERACTUATED REMOTELY OPERATED VEHICLE USING AXIOMATIC DESIGN THEORY — PART 1

In this paper, Axiomatic Design (AD) theory was adopted for the design analysis of an underactuated Remotely Operated Vehicle (ROV) system and its subcomponents. The system design issues of the Propulsion and Control System of the ROV II are analyzed and addressed based on the Independence Axiom methodology. The top-level Functional Requirements (FRs) for the thruster design and configuration are identified and its corresponding Design Parameters (DPs) are also presented.