• The Journal of Korea Robotics Society
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• v.4 no.4
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• pp.265-272
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• 2009

IVarious driving mechanisms to adapt to uneven environment have been developed for many urban search and rescue (USAR) missions. A tracked mechanism has been widely used to maintain the stability of robot's pose and to produce large traction force on uneven terrain in this research area. However, it has a drawback of low energy efficiency due to friction force when rotating. Moreover, single tracked mechanism can be in trouble when the body gets caught with high projections, so the track doesn't contact on the ground. A transformable tracked mechanism is proposed to solve these problems. The mechanism is designed with several articulations surrounded by tracks, used to generate an attack angle when the robot comes near obstacles. The stair climbing ability of proposed robot was analyzed since stairs are one of the most difficult obstacles in USAR mission. Stair climbing process is divided into four separate static analysis phases. Design parameters are optimized according to geometric limitations from the static analysis. The proposed mechanism was produced from optimized design parameters, and demonstrated in artificially constructed uneven environment and the actual stairway.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.2
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• pp.198-202
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• 2009

Urban Search and Rescue (USAR) involves locating, rescuing (extricating), and medically stabilizing victims trapped in confined spaces. In this paper we state the current approach to USAR, address the limitations and discuss the way for moving in rugged topography. To achieve objectives such as surveillance, reconnaissance, and rescue, it is necessary to develop a driving mechanism that can handle rugged geographical features. We propose a new type of driving mechanism for a rescue robot that has a variable shape single-track. By using a variety shapes, it can get the gain of steering and rotating and the ability to overcome stairs. In this paper, we analyzed the design parameters for making variable transform shapes and determined the specifications of the robot to enhance adaptability to stairs.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.143-144
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• 2009

• 한국방재학회:학술대회논문집
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• 2010.02a
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• pp.71.1-71.1
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• 2010

21C 고도의 도시화로 인하여 인구과밀화 및 초대형 초고층 건물의 비약적인 확산은 재난의 규모와 양상에 변화를 가져오며, 도시형 재난재해에 대비한 새로운 대책의 필요성을 과제로 안기고 있다. 뿐 만 아니라 지구온난화 및 뉴 테러리즘의 경향은 복합적이고 동시다발적인 재난으로 인한 다수인명피해에 대한 방호기능의 중요성과 통합재난관리 시스템의 중요성을 더욱 부각시키고 있다. 이러한 거시환경의 변화에 따라 다양화된 위험요인에 대한 체계적 대비와 효과적 대응을 위해 분야별 전문대응조직과 스페셜리스트 양성이 시급한 과제로 대두되고 있으며, 특히 재난대응단계에서 지진 등 건물붕괴로 인하여 동시다발적인 초대형 재난재해 시 효율적인 인명구조 활동의 대책으로 도시탐색구조 체계의 선진화 방안이 필요하며, 이를 위하여 소방공무원을 대상으로 실시한 의식조사 분석결과를 제시하고자 한다.

• The Journal of Korea Robotics Society
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• v.3 no.3
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• pp.186-193
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• 2008

We propose a novel real-time obstacle avoidance method for rescue robots. This method, named the ELA(Emergency Level Around), permits the detection of unknown obstacles and avoids collisions while simultaneously steering the mobile robot toward safe position. In the ELA, we consider two sensor modules, PSD(Position Sensitive Detector) infrared sensors taking charge of obstacle detection in short distance and LMS(Laser Measurement System) in long distance respectively. Hence if a robot recognizes an obstacle ahead by PSD infrared sensors first, and judges impossibility to overcome the obstacle based on driving mode decision process, the order of priority is transferred to LMS which collects data of radial distance centered on the robot to avoid the confronted obstacle. After gathering radial information, the ELA algorithm estimates emergency level around a robot and generates a polar histogram based on the emergency level to judge where the optimal free space is. Finally, steering angle is determined to guarantee rotation to randomly direction as well as robot width for safe avoidance. Simulation results from wandering in closed local area which includes various obstacles and different conditions demonstrate the power of the ELA.

• Ocean Systems Engineering
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• v.5 no.2
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• pp.125-138
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• 2015

In this study, hydrodynamic performance of a 400 mm diameter horizontal axis marine current turbine model was tested in a cavitation tunnel with 1.21 m x 0.8 m cross-section for over a range of tip speed ratios. Torque and thrust data, as well as cavitation visualizations, for certain operating conditions were acquired. Experimental results indicated that the turbine can be exposed to significant amount of sheet and cloud cavitation over the blades along with vortex cavitation at the blade tips. Inception and distribution of cavitation along the blades of the model turbine were then modelled numerically for design operating conditions using a vortex lattice method. The method was also applied to a turbine tested previously and obtained results were compared with the data available. The comparison between simulation results and experimental data showed a slight difference in terms of span-wise extent of the cavitation region. The cloud and tip vortex cavity observed in experiments cannot be modelled due to the fact that the VLM lacks the ability to predict such types of cavitation. Notwithstanding, the use of such prediction methods can provide a reasonably accurate approach to estimate, therefore take the hydrodynamic effects of cavitation into account in design and analysis of marine current turbines.