Jonghui Han

Learn More
The thruster is the crucial factor of an underwater vehicle system, because it is the lowest layer in the control loop of the system. However, an accurate and practical thruster model has not been utilized yet. In this paper, we propose an accurate and practical thrust modeling for underwater vehicles which considers the effects of ambient flow velocity. In(More)
In this paper, redundancy resolution of underwater vehicle-manipulator system(UVMS) is addressed. In general, UVMS has redundant degrees of freedom(DOFs) as many as DOFs of manipulator and these redundant DOFs can be used to optimize the configuration of UVMS while satisfying given tasks. We propose a performance index for redundancy resolution which(More)
To improve the maneuverability of underwater vehicles, accurate thrust model is required. However, its modeling is not only difficult but also inaccurate, because it has highly nonlinear dynamics and many parameters which cannot be modeled exactly. Generally, a propeller's steady-state axial thrust is proportional to the signed square of propeller shaft(More)
In this paper, coordinated motion control of underwater vehicle-manipulator system (UVMS) is addressed. In order for UVMS to carry out manipulation tasks alone, motion planning with consideration of redundancy and tracking control under disturbances are required. We propose redundancy resolution with optimization of restoring moments as motion planning and(More)
In this paper, we describe the design of a novel crane system for use in a small argon hot-cell where only a mechanical master-slave manipulator (MSM) within the limitation is available for the maintenance of the crane. To get a practically achievable solution for the design problem, we devised a remote actuation mechanism in which the electrical parts of(More)
This paper introduces a manipulator that is under development as a remote maintenance tool in the argon-filled cell of PRIDE, a nuclear facility. This remote manipulator was designed to be able to operate in areas where other remote equipment such as a mechanical master-slave manipulator or bridge-transported dual servo manipulator cannot reach. The remote(More)
This paper presents a novel approach to estimate the load performance curves of DC motors whose equations are represented as a function of the torque based on a steady-state model with constraints. Since a simultaneous optimization of the curves forms a multi-objective optimization problem (MOP), we apply an optimal curve fitting method based on a(More)
In this paper, we propose a multi-task scheduler by considering the underwater risk assessment for autonomous underwater vehicle. We divide the task scheduler into two parts: a path coordinator and a condition interpreter. The path coordinator finds the minimum cost sequence from several combinations of paths by using a genetic algorithm. The condition(More)
In this paper, we suggest the mission planning method for autonomous underwater vehicle. In order to set the optimal mission scheduling, we solve the traveling salesman problem using genetic algorithm, and we suggest the cost function which considering both Euclidean distance and current information. In additionally, constraints such as priority and(More)
This paper proposes the behavior learning algorithms for improving the performance of unmanned underwater vehicles (UUVs). Basically, the motion of a UUV with behavior-based controls is determined by the behaviors' outputs which are calculated based on the uncertain dynamic models. Therefore, the performance of a UUV can be improved by learning the dynamic(More)
  • 1