Ngoc-Huy Tran

Study on underwater wireless communication system using LED

In this paper, a new variable-focus LED light device is developed for underwater communication. Usually used as an underwater lighting fixture, the LED light device in this study is utilized as an underwater communication device (UCD) by controlling the distance between light source and lens when communication is needed. A transmission and a receiving part of LED light for communication using photoelectric sensor and Fresnel lens are also developed. The communication system was tested in fresh water and sea water to verify its communication performance; results of which are presented in this study.

Development of Rotational Motion Estimation System for a UUV/USV based on TMS320F28335 microprocessor

For the accurate estimation of the position and orientation of a UUV (unmanned underwater vehicle), a low-cost AHRS (attitude heading reference system) was developed using a low-cost IMU (inertial measurement unit) sensor which provides information on the 3D acceleration, 3D turning rate and 3D earth-magnetic field data in the object coordinate system. The main hardware system is composed of an IMU sensor (ADIS16405) and TMS320F28335, which is coded with an extended kalman filter algorithm with a 50-Hz sampling frequency. Through an experimental gimbal device, good estimation performance for the pitch, roll, and yaw angles of the developed AHRS was verified by comparing to those of a commercial AHRS called the MTi system. The experimental results are here presented and analyzed.

Tracking Control of an Unmanned Surface Vehicle

Nowaday, unmanned surface vehicle (USV) has been a special attention for marine research and surveying exploration in costal area. This paper describes an analysis about architecture and control system of a USV disposed with three fixed thrusters. Therefore, hardware and software architectures of control system will be mentioned and functions of all parts are clarified. A strategy design for tracking waypoints is presented. And this algorithm will be checked by simulation and experiments.

Study on Design, Analysis and Control an Underwater Thruster for Unmanned Underwater Vehicle (UUV)

Unmanned underwater vehicle (UUV) is a type of robot that operates underwater for multi purposes such as underwater exploration purpose, hydro-meteorological exploration, and military purposes…. One of the most important part in the UUV is its thruster. This paper presents the design, analysis and control results of an underwater thruster of 300 W, which can be used for a small-sized UUV. The underwater thruster is designed by integrating different modules and built according to each system from mechanical design, hardware design, and control algorithm to ensure the thruster can operate underwater continuously in the depth of 100 m lifespan (equal to 145 psi) for long time. The thruster use magnetic coupling for waterproof and also can perform the overload protection for thruster. The housing and magnetic coupling were analyzed by using finite element analysis to optimize the thickness of the housing in deep water level. The mathematical model and simulation result of the speed control using PID and Fuzzy controllers are also presented.

Steering and Diving Control of a Small-Sized AUV

This paper presents a steering and diving control of an autonomous underwater vehicle (AUV) platform named KAUV, which is designed as a torpedo with light weight and small size. Through a unique ducted propeller and rudder located at the aft, the KAUV can perform horizontal motion. It also control pitch angle and depth motion with an inside mass shifter mechanism which changes the vehicle center of gravity. Because the system to be controlled is highly nonlinear, a sliding mode control (SMC) is constructed to compensate the effects of modeling nonlinearity, parameter uncertainty, and disturbance. This proposed control algorithm is derived from the linearized vehicle dynamics for steering and diving planes. To check the response of the vehicle system with the developed controllers, a series of simulation results are also simulated and presented.

A Study on the Dynamics of Marine Umbilical Cable for Underwater Vehicle

The dynamics of underwater umbilical cable (UC) for underwater vehicle (UV) are an important in ocean engineering. These UC are widely used in the ocean environment for signal and power transmission application. To apply the cable to power and data transmission for small UV, the dynamics of the UC are studied in the paper. The nonlinear and coupled UC dynamics are complicated, but need to be analyzed in real time for application. In the study, the governing equations of cables are established based on the catenary equation method. The shooting method is applied to solve a two-point boundary value problem. This paper presents the formulation and solution of governing equations that can be used to estimate the three dimensions (3-D) position and forces of the cable end point under the action of concentrated and distributed forces due to underwater currents in 3-D. The validity of the proposed method is shown by simulation results.

Design and Implementation of Dynamic Positioning Control System for USV

Nowadays, the dynamic positioning (DP) performance of an unmanned surface vehicle (USV) is receiving special attention for marine research and surveying exploration in coastal areas. So, this paper describes a structure design of a USV disposed with three thrusters. With this disposition, by means of active thrust, the USV can be controlled at a fixed position with fixed heading. Also, hardware and software architectures of the control system are addressed and the functions of all parts are clarified. A strategy for DP control is presented to compensate the deviations due to disturbances from waves, wind, sea current, or sensor inaccuracy. Finally, according to this developed strategy, a number of experiments were performed through sea trials and the results will be shown.

Study on Design for a New Underwater Disk Robot

This paper describes an analysis of the architecture and control system of a new disk-shaped underwater robot entitled an underwater disk robot (UDR) which has six degrees of freedom (DOF) motion. The UDR has three symmetrical thrusters disposed around the perimeter of a circular chassis, each facing 120 degrees apart from the others. With this disposition, the UDR has omnidirectional manoeuvrability without heading motion. Also, motion of the disk-shaped UDR can be less affected by side disturbances with a robust and swift motion along any directions. The planar motion mechanism (PMM) test and computational fluid dynamics (CFD) analysis were carried out to predict the drag force on the UDR body. Finally, the mechanical design of the UDR and the dynamics analysis including actuator mechanics were presented.

Design and Analysis on a New Underwater Robot

This paper describes the analysis of the architecture, and control system of a new underwater robot named underwater disk robot (UDR), which has six degrees of freedom (DOF) motion. With such thruster positions, the vehicle has omnidirectional manoeuvrability without heading motion. Also, the motion of the streamline disk-shaped UDR hull is less affected by side disturbances because the UDR can move robustly, swiftly along any direction, and the hull reduce the drag force on its body in the horizontal motion. Heave and pitch motion simulation studies of the UDR were carried out with the computational fluid dynamics (CFD) software. required format.