Optical fiber sensors have attracted considerable attention for marine environment and marine structural health monitoring, owing to advantages including resistance to electromagnetic interference, durability under extreme temperature and pressures, light weight, high transmission rate, small size and flexibility. In this paper, the optical fiber sensors employed for marine environment and marine structural health monitoring are summarized for the understanding of their basic sensing principles, and their various sensing applications such as physical parameters, chemical parameters and structural health monitoring. This review paper shows the feasibility of using optical fiber sensing technology for marine application and, due to the aforementioned advantages, it is possible to envisage a widespread use in this research field in the next few years.

Optical fiber sensing for marine environment and marine structural health monitoring: A review

Investigation of the vectored thruster AUVs based on 3SPS-S parallel manipulator

In this work a design for self-tuning non-linear Fuzzy Proportional Integral Derivative (FPID) controller is presented to control position and speed of Multiple Input Multiple Output (MIMO) fully-actuated Autonomous Underwater Vehicles (AUV) to follow desired trajectories. Non-linearity that results from the hydrodynamics and the coupled AUV dynamics makes the design of a stable controller a very difficult task. In this study, the control scheme in a simulation environment is validated using dynamic and kinematic equations for the AUV model and hydrodynamic damping equations. An AUV configuration with eight thrusters and an inverse kinematic model from a previous work is utilized in the simulation. In the proposed controller, Mamdani fuzzy rules are used to tune the parameters of the PID. Nonlinear fuzzy Gaussian membership functions are selected to give better performance and response in the non-linear system. A control architecture with two feedback loops is designed such that the inner loop is for velocity control and outer loop is for position control. Several test scenarios are executed to validate the controller performance including different complex trajectories with and without injection of ocean current disturbances. A comparison between the proposed FPID controller and the conventional PID controller is studied and shows that the FPID controller has a faster response to the reference signal and more stable behavior in a disturbed non-linear environment.

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Trajectory following and stabilization control of fully actuated AUV using inverse kinematics and self-tuning fuzzy PID.

Numerical and experimental studies of heave damping and added mass of spar with heave plates using forced oscillation

This paper presents an inverse kinematic model for an Autonomous Underwater Vehicle (AUV) with 8 thrusters. The vehicle configuration allow the AUV to have a fully-actuated 6 Degrees of freedom (DOF). Rigid body dynamic model and water environment hydrodynamic model are used in this study. The model is implemented and tested using Matlab and Simulink. A 3D model of the AUV is designed for illustration in this work using Autodesk MAYA. Cascaded position and velocity control approach is studied. A conventional linear Proportional Integral Derivative (PID) controller is used for speed control and PD controller for the position control. Ocean current disturbances are introduced to test the system and control stability. Validation of the model is performed with tests for speed stabilization and position control with and without disturbances.

Position Control and Stabilization of Fully Actuated AUV using PID Controller

Autonomous Underwater Vehicles (AUV) are slow-moving small unmanned robots capable of swimming independently below the water surface on pre-defined mission paths and are commonly used for oceanographic exploration, bathymetric surveys and military applications. With the use of appropriate sensors and equipment, AUVs can perform underwater object recognition and obstacle avoidance. Amogh is a miniature AUV developed at Centre For Innovation (CFI), IIT Madras for AUVSI RoboSub competition. The vehicle has a non-conventional dual hull heavy bottom hydrodynamic design equipped with six thrusters which allow for motion control in 4 degrees of freedom. This paper presents various aspects of the unique design of the vehicle. The performance of a simple PID controller for steady depth and heading control has been discussed. Simulations performed on a decoupled mathematical model of the vehicle are compared against experimental results.

Mahesh J. Rao

Papers

Design and motion control of Autonomous Underwater Vehicle, Amogh

CFD approach to heave damping of spar with heave plates with experimental validation

Numerical and experimental studies of heave damping and added mass of spar with heave plates using forced oscillation