• 한국해양공학회지
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• 제26권5호
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• pp.47-54
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• 2012

In this study, numerical simulations were performed to evaluate the current loads acting on the multi-legged underwater robot "Crabster" with a variety of incident angles using the ANSYS-CFX package. The Reynolds-averaged Navier-Stokes equations were solved to simulate the fluid flow around Crabster to calculate the forces and moments induced by incoming currents with various angles. First, to assess the posture stability of the body, the forces and moments were calculated with various incident angles when the current acted in the vertical and horizontal directions. Next, two forms of legs (box and foil types) were evaluated to determine the hydrodynamic force variation. Finally, the current forces and moments acting on the Crabster body with the legs attached were estimated.

• 대한임베디드공학회논문지
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• 제12권5호
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• pp.331-341
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• 2017

This paper presents the sea-trial results of Crabster CR6000 which is a deep-sea walking robot developed by KRISO in 2016. Crabster CR6000 is designed to inspect deep-sea environment rejecting the disturbance on the silent and calm abyssal area. The sea-trial was conducted at the East Sea and the Philippine Sea on December 2016. The Crabster CR6000 undocked successfully from the Shuttle after touchdown on the sea-bed and walked out on the soft sediment soil of the 4,743m seafloor at the fourth diving in the Philippine Sea. The advanced technologies and capabilities of CR6000 were verified from the operational and functional test conducted in the sea-trial. The experimental data acquired from the sea-trial were summarized and the first experience of the deep-sea walking robot was presented in this paper.

• 로봇학회논문지
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• 제7권4호
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• pp.284-291
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• 2012

Recently, development of underwater robot has actively been in progress in the world as ROV(Remotely Operator Vehicle) and AUV(Autonomous Unmmanded Vehicle) style. But KIOST(Korea Institute of Ocean Science and Technology), beginning in 2010, launched the R&D project to develop the robot, dubbed CRABSTER(Crab + (Lob)ster) in a bid to enhance the safety and efficiency of resource exploration. CRABSTER has been designed to be able to walk and swim with its own legs without screws. Among many research subjects regarding CRABSTER, optimal swimming patterns are handled in this paper. In previous studies, drag forces during one period with different values for angle of each joint were derived. However kinematics of real-robot and fluid-dynamics are not considered. We conducted simulations with an optimization algorithm for swimming by considering simplified fluid dynamics in this paper. Drag-coefficients applied to the simulation were approximated values calculated by CFD(Computational Fluid Dynamics : Tecplot 360, ANSYS). In addition, optimized swimming patterns were applied to a real robot. The experiments with the real robot were conducted in circumstances in the water. As a result, when the experiments were carried out in the water, a regular pattern of drag force output came out depending on the movement of the robot. We confirmed the fact that the drag forces from the simulation and the experiment has a high similarity.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2011년도 후기공동학술대회 논문집
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• pp.77-78
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• 2011

한국해양연구원에서 개발 중인 Crabster 로봇팔을 기구학적으로 분석하고, 속도기구학을 매트랩을 이용하여 작업공간에 대해서도 분석 및 해석을 완료하였다. 운용자와 Crabster 로봇팔의 움직임을 고려해 개념 설계한 인간팔 크기의 7축 마스터 암 및 그립퍼의 기구부에 대해 2D 및 3D의 도면을 완성하였고, 마스터 암에 적용할 모터의 사양과 각 관절에 피드백 된 힘을 반영하기 위한 구동 모터의 엔코더를 이용한 위치 센서, DSP2812를 이용한 제어 명령 입력 장치와 구동 모터 드라이버를 포함한 마스터 - 슬레이브 시스템의 개념 설계를 완성하였다.

• 제어로봇시스템학회논문지
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• 제19권9호
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• pp.782-790
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• 2013

In this paper, we propose a better solution for swimming plans of an articulated underwater robot, Crabster, with a view point of biomimetics. As a biomimetic model of underwater organisms, we chose diving beetles structurally similar to Crabster. Various swimming locomotion of the diving beetle has been observed and sorted by robotics technology through experiments with a high-speed camera and image processing software Image J. Subsequently, coordinated patterns of rhythmic movements of the diving beetle are reproduced by simple control parameters in a parameter space which make it easy to control trajectories and velocities of legs. Furthermore, a simulation was implemented with an approximated model to predict the motion of the robot under development based on the classified forward and turning locomotion. Consequently, we confirmed the applicability of parameterized leg locomotion to the articulated underwater robot through the simulated results by the approximated model.

• International Journal of Ocean System Engineering
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• 제1권4호
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• pp.222-229
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• 2011

In this paper, we present the concept and main mission of the Crabster, an underwater walking robot. The main focus is on the modeling of drag and lift forces on the legs of the robot, which comprise the main difference in dynamic characteristics between on-land and underwater robots. Drag and lift forces acting on the underwater link are described as a function of the relative velocity of the link with respect to the fluid using the strip theory. Using the translational velocity of the link as the rotational velocity of the joint, we describe the drag force as a function of joint variables. Generalized drag torque is successfully derived from the drag force as a function of generalized variables and its first derivative, even though the arm has a roll joint and twist angles between the joints. To verify the proposed model, we conducted drag torque simulations using a simple Selective Compliant Articulated Robot Arm.

• 한국해양공학회지
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• 제27권6호
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• pp.65-72
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• 2013

This paper describes a finite element analysis (FEA) of the body frame of a subsea robot, Crabster200 (CR200). CR200 has six legs for mobility instead of screw type propellers, which distinguishes it from previous underwater robots such as remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs). Another distinguishing characteristic is the body frame, which is made of carbon fiber reinforced plastic (CFRP). This body frame is designed as a rib cage structure in order to disperse the applied external loads and reduce the weight. The frame should be strong enough to support many devices for exploration and operation underwater. For a reasonable FEA, we carried out specimen tests. Using the obtained material properties, we performed a modal analysis and FEA for CR200 with a ready posture. Finally, this paper presents the FEA results for the CFRP body frame and the compares the characteristics of CFRP with conventional material, aluminum.

• 대한기계학회논문집A
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• 제38권4호
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• pp.419-425
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• 2014

본 논문은 200 미터급 다관절 복합이동 해저로봇(크랩스터, CR200)에 적용된 탄소섬유 복합소재 몸체 프레임의 구조해석에 대하여 다루고 있다. CR200 의 몸체 프레임은 탄소섬유 복합소재를 이용한 강화 플라스틱으로 제작되어 가볍고 강하며, 사람의 늑골구조를 모방하여 설계되었기 때문에 외부 하중을 효과적으로 분산시킬 수 있다. 해상에서 모선과 크레인을 사용하여 CR200 을 진수하거나 인양할 때, 해상상황에 따라 모선 운동에 의한 동적 하중이 몸체 프레임에 전달되기 때문에 프레임에 대한 진수 및 인양 조건에서의 구조적 해석이 필요하다. 구조해석의 신뢰성을 확보하기 위하여 본 논문에서는 몸체 프레임의 시편시험 결과를 이용하여 구조해석을 수행하고, 기존 금속재질의 프레임 모델과 구조적 특성을 비교하여 탄소섬유 복합소재 프레임의 구조적 특성을 정량적으로 비교하였다.

• 대한기계학회논문집A
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• 제38권9호
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• pp.989-997
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• 2014

본 논문에서는 6 족 다관절 해저로봇 크랩스터를 위한 정적 보행 알고리즘 설계 방법에 대하여 기술하였다. 정적 보행 알고리즘 설계를 위해 보행계획 벡터와 다리쌍 벡터의 개념을 도입하여 6 족 로봇 보행기법 설계의 편의성과 확장성을 확보하고, 이를 이용하여 수중환경이나 탐사조건에 따라 운용할 수 있는 여섯 가지 정적 보행기법을 설계하였다. 그리고, 공통 제어변수를 사용하여 각 보행 간 자유로운 연동과 자세제어와의 복합보행을 수행할 수 있도록 하였다. 설계된 여섯 가지 정적 보행기법은 시뮬레이션을 통하여 확인하였고, 크랩스터에 적용하여 보행기법 간 연동성과 복합보행 기능 등을 검증하였다.

• 대한기계학회논문집A
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• 제39권8호
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• pp.743-749
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• 2015

본 논문에서는 해저보행로봇 크랩스터(CR200)의 전방 입사 조류에 대한 동적 전복안정성에 대하여 연구하였다. CR200 은 우리나라 근해 환경의 특징인 강조류 환경에서 운용될 수 있도록 설계되었고, 몸체도 유체역학적 요소를 고려하여 제작되었다. 해저보행로봇의 동적 전복안정성을 판단하기 위하여 육상보행로봇의 동적 전복안정성의 개념을 도입하여 수중환경에 맞도록 전복 판별식을 재정의하고 이를 이용해 전방 조류에 대한 동적 전복안정성을 시뮬레이션으로 해석하였다. 이를 위하여 조류속도가 변할 때 CR200 의 자세변화에 따른 유동해석 결과를 이용하였다. 또한 CR200 의 지지다리를 이동하여 전복축의 위치가 바뀌었을 경우에 대하여 해석을 수행하여 전복축의 이동에 따른 CR200 의 전복안정성 개선효과를 확인하였다.