• Journal of Advanced Marine Engineering and Technology
• /
• v.39 no.5
• /
• pp.522-526
• /
• 2015

Generally, underwater unmanned vehicle have adopted an inertial navigation system (INS), dead reckoning (DR), acoustic navigation and geophysical navigation techniques as the navigation method because GPS does not work in deep underwater environment. Even if the tactical inertial sensor can provide very detail measurement during long operation time, it is not suitable to use the tactical inertial sensor for small size and low cost UUV because the tactical inertial sensor is expensive and large. One alternative to INS is attitude heading reference system (AHRS) with the micro-machined electro mechanical system (MEMS) inertial sensor because of MEMS inertial sensor's small size and low power requirement. A cost effective and small size attitude heading reference system (AHRS) which incorporates measurements from 3-axis micro-machined electro mechanical system (MEMS) gyroscopes, accelerometers, and 3-axis magnetometers has been developed to provide a complete attitude solution for UUV. The AHRS based MEMS overcome many problems that have inhibited the adoption of inertial system for small UUV such as cost, size and power consumption. Several evaluation experiments were carried out for the validation of the developed AHRS's function and these experiments results are presented. Experiments results prove the fact that the developed MEMS AHRS satisfied the required specification.

• Journal of Institute of Control, Robotics and Systems
• /
• v.22 no.7
• /
• pp.562-569
• /
• 2016

This paper proposes a navigation system with a robust localization method for an underwater unmanned vehicle. For robust localization with IMU (Inertial Measurement Unit), a DVL (Doppler Velocity Log), and depth sensors, the EKF (Extended Kalman Filter) has been utilized to fuse multiple nonlinear data. Note that the GPS (Global Positioning System), which can obtain the absolute coordinates of the vehicle, cannot be used in the water. Additionally, the DVL has been used for measuring the relative velocity of the underwater vehicle. The DVL sensor measures the velocity of an object by using Doppler effects, which cause sound frequency changes from the relative velocity between a sound source and an observer. When the vehicle is moving, the motion trajectory to a target position can be recorded by the sensors attached to the vehicle. The performance of the proposed navigation system has been verified through real experiments in which an underwater unmanned vehicle reached a target position by using an IMU as a primary sensor and a DVL as the secondary sensor.

• Journal of Ocean Engineering and Technology
• /
• v.32 no.2
• /
• pp.131-137
• /
• 2018

In this paper, we propose an adaptive backstepping controller to control the exact position and orientation of a remotely operated underwater vehicle with parametric model uncertainty. To further improve the angular velocity control precision of each thruster, a phase locked loop (PLL) controller has been added to the backstepping controller. A comparison of two backstepping controllers with and without the PLL control loop has been performed using simulations and experiments. The test results showed that the tracking performance could be improved by using the PLL control loop in the proposed adaptive backstepping controller.

• Journal of Ocean Engineering and Technology
• /
• v.20 no.3 s.70
• /
• pp.7-14
• /
• 2006

This paper discusses the structural design and analysis of a 6,000 meters depth-rated capable deep-sea unmanned underwater vehicle (UUV) system. The UUV system is currently under development by Maritime and Ocean Engineering Research Institute(MOERI), Korea Ocean Research and Development Institute (KORDI). The UUV system is composed of three vehicles - a Remotely Operated Vehicle (ROV), an Autonomous Underwater Vehicle (AUV) and a Launcher - which include underwater equipment. The dry weight of the system exceeds 3 tons hence it is necessary to carry out the optimal design of structural system to ensure the minimum weight and sufficient space within the frame for the convenient use of the embedded equipments. In this paper, therefore, the structural design and analysis of the ROV and launcher frame system were carried out, using the optimizing process. The cylindrical pressure vessels for the ROV were designed to resist the extreme pressure of 600 bars, based on the finite element analysis. The collapse pressure for the cylindrical pressure vessels was also checked through a theoretical analysis.

• Journal of Ocean Engineering and Technology
• /
• v.14 no.2
• /
• pp.7-12
• /
• 2000

This paper presents a non-regressor based adaptive control scheme for the trajectory tracking of underwater vehicle-mounted manipulator systems(UVMS). The adaptive control system includes a class of unmodeled effects is applied to the trajectory control of an UVMS. The only information required to implement this scheme ios the upper bound and lowe bound of the system parameter matrices the upper bound of unmodeled effects the number of joints the position and attitude of the vehicle and trajectory commands. The adaptive control law estimates control gains defined by the combinations of the bounded constants of system parameter matrices and of a filtered error equation. To evaluate the performance of the non-regressor based adaptive controller computer simulation was performed with a two-link planar robot model mounted on an underwater vehicle. The hydrodynamic effects acting on the manipulator are included. It is assumed that the vehicle's motion is slow and can be predicted with a proper compensator.

• Journal of Ocean Engineering and Technology
• /
• v.32 no.6
• /
• pp.511-517
• /
• 2018

This paper proposes a vision-based underwater laser scanner with separate structures for an underwater camera and a line laser projector. Because the two devices can be adaptively placed regardless of the features of the unmanned underwater vehicle (UUV), the scanner has significant advantages in relation to its availability and flexibility. Position calibration between the underwater camera and laser projector guarantees a 3D measuring performance with high accuracy. To verify the proposed underwater laser scanner, a test-bed system was manufactured, which consisted of the laser projector, camera, Pan&Tilt, and Attitude and Heading Reference System (AHRS). A camera-laser calibration test and simple 3D reconstruction test were performed in a water tank and the experimental results are reported.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.14 no.5
• /
• pp.781-787
• /
• 2011

Mine countermeasure missions(MCMs) may induce the loss of human and ship because of the covert of mine. In recent years, unmanned underwater vehicles(UUVs) have emerged as viable technical solution for conductimg underwater search, surveillance, and clearance operations in support of mine countermeasure missions because of her autonomy and long time endurance capability. This paper introduces a technical approach to mine countermeasure mission effectiveness analysis and presents some simulation-based analysis results for engineering of the UUV system definition which could be support analysis of alternatives for system definition and design.

• Journal of Institute of Control, Robotics and Systems
• /
• v.18 no.9
• /
• pp.830-836
• /
• 2012

According to increasing the importance of underwater environments, the needs of UUV are growing. This paper represents the mechanism and algorithm of UUV docking system with 21-inch torpedo tubes for military submarines as a docking station. To improve the reliability of the docking, torpedo tubes launch a wired ROV and next the ROV combined with UUV is retrieved. For estimating the relative position between the ROV and UUV, in this paper, combining RF sensors and vision system is proposed. The RSSI method of RF sensors is used to estimate the distance and the optical image is combined for the directional information.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.15 no.4
• /
• pp.410-416
• /
• 2012

In recent years, unmanned underwater vehicles(UUVs) have emerged as viable technical solution for conducting underwater search, surveillance, and clearance operations in support of mine countermeasure missions(MCMs) because of her autonomy and long time endurance capability. It is necessary for UUV for MCM system design to define system specification from various configuration alternatives. This paper introduces a simulation model for mine countermeasure mission effectiveness analysis and presents some simulation results under various tide conditions for validation of the proposed simulation model.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.54 no.4
• /
• pp.3-9
• /
• 2017

Due to difficulties of continuous electric power provision to underwater communication nodes, the efficient power usage is highly required in underwater network protocol. In this paper, we studied the energy efficient MAC(Medium Access Control) protocol for underwater network supporting mobile nodes such as UUV(Unmanned Underwater Vehicle) and AUV(Autonomous Underwater Vehicle). The mobile nodes could waste the electric power in vain when the receiver moves out of the radio propagation coverage during the data exchange and thus the transmitted data fails in reaching the receiver. Expecially, such a failure is much more obvious in underwater acoustic channels since the propagation delay is about $10^5$ times slower than in terrestrial radio channels. This proposed mobility-MAC controls the data dropping stochastically in the Dropping Zone by considering the receiver's location and moving velocity. In conclusion, this selective dropping method not only improves latency and throughput by reducing invalid droppings but also boosts power efficiency by valid droppings.