• ICROS
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• v.19 no.3
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• pp.17-28
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• 2013

조수간만의 차가 크고 지형이 복잡한 우리나라서 해안은 세계적으로도 보기 드문 강조류 환경이다. 잠수부의 안전을 위협하는 이러한 환경은 수중로봇의 접근도 쉽게 허락하지 않는다. 해저로봇 크랩스터는 이러한 특수한 환경을 조사하기 위해 고안된 수중보행로봇이다. 기존의 프로펠러 방식으로 달성하기 어려웠던 문제점을 크랩스터 로봇은 게나 가재와 같은 수중 생명체를 모방하여 극복하고자 했다. 크랩스터는 게나 가재의 기능을 모방함으로써 강조류 악시계 환경에서 유용한 두 가지 특징을 얻는다. 첫째는 해저에 밀착하여 자세를 제어함으로써 조류력을 이용하여 자세를 안정화시키면서 이동할 수 있다. 둘째는 조류 속에서 동요하지 않는 안정된 자세를 바탕으로 깨끗한 초음파 영상을 얻을 수 있다. 이는 강조류 환경에서 동반되는 부유물에 의한 악시계 환경을 극복할 수 있는 중요한 수단을 제공한다. 본 고에서는 이러한 개념에 따라 설계 개발된 크랩스터 CR200의 구성과 사양을 소개하고, 여기에 사용된 핵심기술을 살펴본다. 또한, 최근 수행된 CR200의 시험 결과에 대해서도 요약 소개한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.8
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• pp.743-749
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• 2015

In this paper, we describe the dynamic tumble-stability analysis of a seabed-walking robot named Crabster (CR200) in forward-incident currents. CR200 is designed to be operated in tidal-current conditions, and its body shape is also designed to minimize hydrodynamic resistances considering hydrodynamics. To analyze its tumble stability, we adopt the dynamic stability margin of a ground-legged robot and modify the definition of the margin to consider tidal-current effects. To analyze its dynamic tumble stability, we use the estimated hydrodynamic forces that act on the robot in various tidal-current conditions, and analyze the dynamic tumble-stability margin of the robot using the estimated results obtained for the various tidal-current conditions. From the analyses, we confirm the improved tumble stability of the robot according to the movement of the tumble axis caused by the supporting points of the legs.

• Journal of Ocean Engineering and Technology
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• v.29 no.5
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• pp.398-403
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• 2015

This paper introduces a method to estimate the contact-force of the leg of a walking robot and proposes a solution to a shortcoming of the previous study. This shortcoming was the deteriorating performance when estimating the contact-force whenever the rotation of each joint was reversed. It occurred because the friction-torque of each joint was not considered. In order to solve this problem, a friction-torque model for a robot leg was developed based on repetitive experimentation and used to improve the contact-force estimation performance. We verified the performance of the proposed method experimentally.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.10a
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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.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.4
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• pp.419-425
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• 2014

This study applied finite element analysis (FEA) to the body frame of the 200-meter class multi-legged subsea walking robot known as Crabster (CR200). The body frame of the CR200 is modeled after the ribcage of a human so that it can disperse applied external loads. It is made of carbon-fiber-reinforced plastic (CFRP). Therefore, the frame is lighter and stronger than it would be if it were made of other conventional materials. In order to perform FEA for the CFRP body frame, we applied the material properties of the CFRP as obtained from a specimen test to an FE model of CFRP frame. Finally, we performed FEA with respect to the load conditions encountered when the robot is launched into and recovered from the sea. Also, we performed FEA for the frame, assuming that it was fabricated using a conventional material, in order to compare its characteristics with CFRP.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.5
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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.

• Journal of Ocean Engineering and Technology
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• v.26 no.6
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• pp.59-65
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• 2012

In this research, a novel mater arm was studied as a teaching device for an underwater revolute robot arm used as a slave arm. The master arm was designed to be a seven-degree-of-freedom (DOF) structure, with a structure similar to that of the slave arm, and to be desktop size to allow it to be worn on a human arm. The master arm with encoders on the joints was used as an input device for teaching a slave robot arm. In addition, small electric magnets were installed at the joints of the master arm to generate the haptic force. A control system was designed to sense excessive force and torque in the joints of the master arm and protect it by controlling the position and velocity of the slave arm through the encoder signal of the master arm.

• Journal of Ocean Engineering and Technology
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• v.26 no.5
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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.

• Journal of Ocean Engineering and Technology
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• v.27 no.6
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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.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.9
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• pp.989-997
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• 2014

In this paper, we describe a design method for the static walking algorithm of a subsea hexapod robot called Crabster (CR200). To design the gait algorithms of a hexapod robot, we propose a design method that uses a gait schedule vector and leg pair vector to secure convenience and expandability. Several walking algorithms are designed that are capable of being applied to CR200 according to the underwater environment and explorative conditions. In addition, gait transition is freely performed between algorithms by applying common control parameters to them. The gait algorithms designed using the proposed method are simulated using MATLAB and validated against the results of experiments.