Young-Sun Ryuh’s research while affiliated with Korea Institute of Industrial Technology and other places

3D mapping is one of the most significant abilities for autonomous underwater vehicles (AUV). This paper proposes a 3D mapping algorithm for a robotic fish using two mechanical scanning sonars (MSSs) with one being forward-looking and the other downward-looking. Combined with inertial measurement unit (IMU), the forward-looking MSS is used for 2D SLAM (simultaneous localization and mapping) by which the 2D poses of the vehicle are optimally obtained by applying a pose-based GraphSLAM. Based on the estimated 2D poses, depth and orientation, the measurements from the downward-looking sonar are used to build the 3D map by adapting 3D mapping algorithm Octomap while taking into account the pose uncertainty. The effectiveness of the proposed algorithm is verified by extensive simulations which also show that it can generate more informative 3D map than the scenario where no uncertainty of poses is considered.

This paper presents a multi-agent robotic fish system used for mariculture monitoring. Autonomous robotic fish is designed to swim underwater to collect marine information such as water temperature and pollution level. Each robotic fish has 5 degrees of freedom for controlling its depth and speed by mimicking a sea carp. Its bionic body design enables it to have high swimming efficiency and less disturbance to the surrounding sea lives. Several onboard sensors are equipped for autonomous 3D navigation tasks such as path planning, obstacle avoidance and depth maintenance. A robotic buoy floating on the water surface is deployed as a control hub to communicate with individual robots, which in turn form a multi-agent system to monitor and cover a large scale sea coast cooperatively. Both laboratory experiments and field testing have been conducted to verify the feasibility and performance of the proposed multi-agent system.

The present invention relates to a docking station whereby an underwater robot can always be overhauled, repaired and operated. According to one aspect of the present invention, a docking station can be provided which comprises: a receiving unit which receives an underwater robot and is disposed below the water surface; a maintenance unit which is provided over the receiving unit and is disposed above the water surface; and a conveyor unit for conveying the underwater robot from the receiving unit to the maintenance unit.

Acoustic communication is one of the essential technologies for many promising underwater systems. In this paper, we focus on the research and development of an acoustic modem for a real-time water quality monitoring system using bio-mimetic fish robots. Challengeable issues from the viewpoint of acoustic communication for the application are first classified and then the detailed study is conducted to meet each design criterion. Also, the implemented modem hardware is verified in terms of functionality and performance through experiments in a lake and a river.

Underwater acoustic communication is a rapidly growing research area nowadays and many related studies have already been conducted in recent decades. Underwater acoustic communication can be easily applied to many fields, such as oceanic data collection, undersea exploration, disaster prevention, underwater environmental monitoring, and tactical surveillance. However, there are many challenges associated with underwater communication, including bandwidth limitations, multi-path propagation, padding, long end-to-end propagation delay, high bit error, temporary loss of connectivity, and limited battery power. To overcome these problems, existing implementable MAC protocols need to be classified in terms of network topology. To improve network mobility, two kinds of network topologies, which include cluster-head-based and ad-hoc-based MAC protocols, are considered. In this paper, we summarize some selected MAC protocols and analyze their performance by comparing a number of factors. We obtain experimental results by developing and simulating the existing numerical models of each protocol practically using simulation tools.

The purposes of this study in multi-robot systems is in the implementation of self-controlled multi-robot systems that operate without human aid in order to eliminate potential human risk by letting them deal with complex and dangerous operations that can't be done by a single robot system. In case of mariculture that draws people's attention in recent years, it is not feasible for human beings to run it by themselves and underwater robots are being considered as an alternative by many people. Since such a mariculture in mother nature is on a large scale and is widespread with various uncertainty including unknown obstacles, however, a single robot can hardly collect all information required, and all of monitoring work will be stopped in case of the robot's breakdown. This paper proposes an underwater swarm robot system in which each of multiple agent robots operates on its own according to its own private environment being able to locate itself based on robot buoys within an environment such as mariculture.

In recent years, there is a rising interest on studying biomimetic fish-like underwater robots because of advantages from mimicking real fish's great maneuverability and high energy efficiency. However, researches about these kinds of underwater robots have not been investigated so much and there are still diverse problems in respect of using of the robotic fish in the real environment such as in the river for monitoring water pollution. Therefore, this study mainly describes development of a robotic fish which can be used for water quality monitoring system. The robotic fish 'Ichthus V5.5' has a 3-DOF serial link-mechanism for its propulsion, which is developed in KITECH. Furthermore, we propose a dynamic equation of the fish robot to use the underwater environment. We added several sensors to navigate autonomously in the real environment like river. Also, we installed two kinds of sensor to detect temperature, electric conductivity, pH (hydrogen ion concentration) of water. Therefore, the developed robotic system can be applied to environmental monitoring system for detect pollution or quality of river.

Recently, there has been large interest on short and medium range underwater communication systems for various applications. In this work, we investigate a moving communication system equipped with bio-inspired fish robots. A protocol stack encompassing physical layer, medium access control layer and network layer is designed for a packet-based hierarchical underwater acoustic communication and the related hardware is implemented. The developed components and system prototype are verified and evaluated in the Han River. Since this system provides high mobility and real-time monitoring service, it could be utilized for pollution monitoring and surveillance in rivers and oceans.

To achieve the goal of low-cost MEMS gyros for the precise self-localization of mobile robots, this paper presents a simple, yet effective method to minimize drifts on the heading angle by combining measurements from a gyro with measurements from wheel encoders (odometry). The main idea of the proposed approach is to estimate the accuracy of both sensors as a function of the actual maneuver being carried out, and then the output of both sensors are fused by the complementary filter taking into account the maneuvering conditions. The proposed method is applied to a mobile robot and the experimental data demonstrate the effectiveness of this approach.

This paper demonstrates Biomimetic fish robot controlling system using by underwater acoustic signal. All the information, results and technical data were collected during implementation in real environment. Through this paper we have focused to create Biomimetic fish robot controlling system with an enhanced design.