• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.78-83
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• 2007

The paper focuses on the establishment of optimized bucket path planning and trajectory control designated for force-reflecting backhoe reacting to excavation environment, such as potential obstacles and ground characteristics. The developed path planning method can be used for precise bucket control, and more importantly for obstacle avoidance which is directly related to safety issues. The platform of this research was based on conventional papers regarding the kinematic model of excavator. Jacobian matrix was constructed to find optimal joint angles and rotation angles of bucket from position and orientation data of excavator. By applying Newton-Raphson method optimal joint angles and bucket orientation were derived simultaneously in the way of minimizing positional errors of excavator. The model presented in this paper was intended to function as a cornerstone to build complete and advanced path planning of excavator by implementing soil mechanics and further study of excavator dynamics together.

• Coupled systems mechanics
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• 제2권1호
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• pp.23-51
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• 2013

An analytical algorithm for the estimation of the resistance forces exerted on the dipper of a cable shovel and the specific energy consumed in the cutting-loading process is presented. Forces due to payload and to cutting of geomaterials under given initial conditions, cutting trajectory of the bucket, bucket's design, and geomaterial properties are analytically computed. The excavation process has been modeled by means of a kinematical shovel model, as well as of dynamic payload and cutting resistance models. For the calculation of the cutting forces, a logsandwich passive failure mechanism of the geomaterial is considered, as has been found by considering that a slip surface propagates like a mixed mode crack. Subsequently, the Upper-Bound theorem of Limit Analysis Theory is applied for the approximate calculation of the maximum reacting forces exerted on the dipper of the cable shovel. This algorithm has been implemented into an Excel$^{TM}$ spreadsheet to facilitate user-friendly, "transparent" calculations and built-in data analysis techniques. Its use is demonstrated with a realistic application of a medium-sized shovel. It was found, among others, that the specific energy of cutting exhibits a size effect, such that it decreases as the (-1)-power of the cutting depth for the considered example application.

• 한국응용과학기술학회지
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• 제38권2호
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• pp.532-542
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• 2021

본 연구의 목적은 골프 스윙 시 3가지 스탠스에서 클럽헤드 스피드와 볼의 정확성을 유지하기 위한 신체 전략을 하지의 운동학적 변인과 지면반력 변인을 통하여 알아보고자 하였다. 연구의 대상은 공식 핸디캡이 2인 남자골프선수 10명으로 하였다. 모든 대상자들은 스탠스 조건(스퀘어, 오픈, 클로즈드)에 따라 어드레스 자세를 유지한 후 스윙을 수행하였다. 3차원 동작분석 시스템과 지면반력기를 이용하여 각 스탠스에 따라 7번 아이언 풀스윙을 수행한 결과를 산출하였다. 연구결과로 신체중심의 변위, 고관절 각변위, 무릎관절 각변위는 차이가 나타나지 않았다. 발목관절 각변위는 어드레스부터 다운스윙까지 왼쪽에서 오픈 스탠스가 저측굴곡이 크게 수행되었고, 오른쪽에서 클로즈드 스탠스에서 저측굴곡이 크게 수행되었다. 지면반력에서 전후, 수직은 차이가 없었지만, 어드레스부터 테이크백까지 왼발은 오른쪽 방향, 오른발은 왼쪽 방향의 힘이 오픈이 클로즈드 스탠스보다 크게 나타났다. 결론적으로 다양한 스탠스에도 불구하고, 임팩트 시 동일한 자세를 유지하는 것이 클럽헤드 스피드와 볼의 방향에 긍정적으로 작용되는 것으로 판단된다.