• 대한전기학회논문지:시스템및제어부문D
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• 제54권3호
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• pp.131-140
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• 2005

Fault-tolerant gait generation of a hexapod robot with crab walking is proposed. The considered fault is a locked joint failure, which prevents a joint of a leg from moving and makes it locked in a known position. Due to the reduced workspace of a failed leg, fault-tolerant crab walking has a limitation in the range of heading direction. In this paper, an accessible range of the crab angle is derived for a given configuration of the failed leg and, based on the principles of fault-tolerant gait planning, periodic crab gaits are proposed in which a hexapod robot realizes crab walking after a locked joint failure, having a reasonable stride length and stability margin. The proposed crab walking is then applied to path planning on uneven terrain with positive obstacles. i.e., protruded obstacles which legged robots cannot cross over but have to take a roundabout route to avoid. The robot trajectory should be generated such that the crab angle does not exceed the restricted range caused by a locked joint failure.

• 로봇학회논문지
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• 제14권4호
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• pp.245-250
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• 2019

Milli-scale crawling robots have been widely studied due to their maneuverability in confined spaces. For successful crawling, the crawling robots basically required to fulfill alternating gait with elliptical foot trajectory. The alternating gait with elliptical foot trajectory normally generates both forward and upward motion. The upward motion makes the aerial phase and during the aerial phase, the forward motion enables the crawling robots to proceed. This simultaneous forward and upward motion finally results in fast crawling speed. In this paper, we propose a novel alternating mechanism to make a crab-inspired eight-legged crawling robot. The key design strategy is an alternating mechanism based on double four-bar linkages. Crab-like robots normally employs gear-chain drive to make the opposite phase between neighboring legs. To use the gear-chain drive to this milli-scale robot system, however, is not easy because of heavy weight and mechanism complexity. To solve the issue, the double-four bar linkages has been invented to generate the oaring motion for transmitting the equal motion in the opposite phase. Thanks to the proposed mechanism, the robot crawls just like the real crab with the crawling speed of 0.57 m/s.

• Biomaterials and Biomechanics in Bioengineering
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• 제2권4호
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• pp.249-269
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• 2015

A problem faced by oil companies is the maintenance of the location register of pipelines that cross the surf zone, the regular survey of their location, and also their inspection. A survey of the state of art did not allow identifying operating systems capable of executing such tasks. Commercial technologies available on the market also do not address this problem and/or do not satisfy the presented requirements. A possible solution is to use robotic systems which have the ability to walk on the shore and in the surf zone, subject to existing currents and ripples, and being able to withstand these ambient conditions. In this sense, the authors propose the development of a spider crab biologically inspired robot to achieve those tasks. Based on these ideas, this work presents a biomechanical study of the spider crab, its modeling and simulation using the SimMechanics toolbox of Matlab/Simulink, which is the first phase of this more vast project. Results show a robot model that is moving in an "animal like" manner, the locomotion, the algorithm presented in this paper allows the crab to walk sideways, in the desired direction.

• 한국지능시스템학회논문지
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• 제21권2호
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• pp.159-164
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• 2011

본 연구에서는 4절 링크 이론(four-bar linkage mechanism)과 얀센 메커니즘(Jansen mechanism)을 기반으로 다관절 보행 로봇(multi-legged walking robot)인 게(crab) 로봇을 제작하고, 게 로봇의 움직임에 대하여 기구학적인 해석을 제시한다. 제작된 게 로봇은 영상 획득을 위하여 카메라를 장착하였고, 장애물 회피를 위하여 3조의 초음파 센서를 가지고 있다. 또한 RF통신으로 외부에 영상 정보를 전달하며, Blue-tooth 통신 모듈을 장착하여 외부로부터 부여된 임무를 수행할 수 있다. 게 로봇의 설계와 제작을 하기 위해서 필요로 하는, 로봇 다리의 움직임을 알기 위해서는 관절 변수와 다리 끝단의 위치 및 자세와의 관계를 얻어야 한다. 따라서, 제안된 기구학적 해석은 로봇의 설계와 제작에 있어서 많은 도움을 주며 중요한 과정이다.

• 제어로봇시스템학회논문지
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• 제18권2호
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• pp.141-148
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• 2012

This paper proposes fault tolerant gaits of a quadruped robot with feet of flat shape. Fault tolerant gaits make it possible for a legged robot to continue static walking against a leg failure. In the previous researches, it was assumed that a legged robot had feet that have point contact with the surface. When the robot is endowed with feet having flat shape, fault tolerant gaits can show better performance compared with the former gaits, especially in terms of the stride length and gait stability. In this paper, fault tolerant gaits of a quadruped robot against a locked joint failure are addressed in straight-line motion and crab walking, respectively.

• 대한전기학회논문지
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• 제43권2호
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• pp.329-338
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• 1994

This paper presents a novel method of path planning for a quadruped walking robot on irregular terrain. In the previous study on the path planning problem of mobile robots, it has been usually focused on the collision-free path planning for wheeled robots. The path planning problem of legged roboth, however, has unique aspects from the point of viw that the legged robot can cross over the obstacles and the gait constraint should be considered in the process of planning a path. To resolve this unique problem systematically, a new concept of the artificial intensity field of light is numerically constructed over the configuration space of the robot including the transformed obstacles and a feasible path is sought in the field. Also, the efficiency of the proposed method is shown by various simulation results.

• 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.

• 한국지능시스템학회논문지
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• 제21권5호
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• pp.660-666
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• 2011

본 논문에서는 절 기구(bar linkage)형 다관절 보행로봇(multi-legged walking robot)의 최적다리 길이선정을 위하여 입자군집 최적화(PSO: Particle Swarm Optimization) 기법을 사용하였다. PSO 알고리즘을 적용하기 위해서 제안한 보행로봇의 기구학적인 해석이 필요하다. 게 로봇은 4절 링크 이론(four-bar linkage)과 얀센 메커니즘(Jansen mechanism)을 기반으로 설계되었다. 이러한 기구학적인 해석을 바탕으로 로봇의 보행보폭을 정의한다. 그리고 PSO의 학습 및 군집 특성을 이용하여 최대의 보행보폭을 가지는 10개(EA)의 링크(link)길이를 구한다. 시뮬레이션을 통해 각 링크의 위치와 다리 끝단의 보행보폭을 확인할 수 있다. 결과로서, PSO기법이 절 기구형 다관절 보행로봇의 최적다리 길이 선정에 효율적임을 보여 준다.

• 한국지능시스템학회논문지
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• 제20권4호
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• pp.509-515
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• 2010

부산과 경남의 경우 해안가뿐 만 아니라 습지 지역과 지역을 통과하는 낙동강의 넓은 남해안 벨트 등 다양한 형태의 환경으로 둘러싸여있다. 이러한 다양한 형태의 부정형 지역에서 활동할 수 있는 로봇의 이동 플랫폼이 요구되고 있다. 하지만 이러한 지형에 바퀴가 달린 감시로봇을 사용한다면 모래나 습지표면에 바퀴가 빠져 움직일 수 없다. 또한, 관절 로봇은 속도가 느리고 몸체가 움직일 때마다 기울어져 넘어질 수 있다. 따라서 본 연구에서는 모래 위, 습지에서 효과적으로 보행할 수 있는 메커니즘을 개발하는 것이다. 개발한 생물체 로봇에 카메라, 적외선 센서 등을 장착하고, 이 센서들을 이용하여 소프트 컴퓨팅 알고리즘을 이용하여 주위 환경에 반응하도록 한다. 또한 블루투스 통신 모듈을 장착하여 외부와 통신하며 외부의 명령에 순응하는 행동을 할 수 있게 한다. 본 연구의 최종 목표는 습지, 모래, 물 위에서 가장 적합하게 작동할 수 있는 생물체를 로봇으로 구현하고, 게 로봇에 부착된 카메라 정보를 통해 필요부분을 감시할 수 있으며, 컴퓨터에 전송된 화면을 보고 사용자가 로봇을 제어 할 수 있는 지능형 로봇을 제작하는 것이다.

• 전기학회논문지
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• 제58권3호
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• pp.614-620
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• 2009

The force distribution in multi-legged robots is a constrained, optimization problem. The solution to the problem is the set points of the leg contact forces for a particular system task. In this paper, an efficient and general formulation of the force distribution problem is developed using linear programming. The considered walking robot is a quadruped robot with a locked-joint failure, i.e., a joint of the failed leg is locked at a known place. For overcoming the drawback of marginal stability in fault-tolerant gaits, we define safety margin on friction constraints as the objective function to be maximized. Dynamic features of locked-joint failure are represented by equality and inequality constraints of linear programming. Unlike the former study, our result can be applied to various forms of walking such as crab and turning gaits. Simulation results show the validity of the proposed scheme.