Crawling robots are advantageous in overcoming obstacles. These robots have characteristics such as light weight and outstanding mobility. In case of large robots, they have difficulties passing narrow gaps or entering the cave. In this paper, we propose a milli-scale hexapedal robot using 4-bar linkages. Two conditions are necessary to enable efficient walking. In short, the trajectory of the foot must be elliptical, and the lowest point of the foot should be the same. These conditions are satisfied with a novel leg design. The robot has a pair of three legs and the legs are coupled to operate simultaneously. Each set of the legs are installed to robot’s both sides and the legs satisfy the equal lowest foot point and elliptical trajectory. As a result, this hexapedal robot can crawl with 0.56m/s speed.

본 연구에서는 양파정식기의 정식시 개공기와 토양 간 상대속도를 최대한 0으로 근접시키기 위해 4절 링크-캠 기구를 갖는 정식시험장치를 제작하여 정식시험을 실시하고 최적 작업조건 및 형상을 구명하였 다. 시험조건은 모종나이 50일, 주간거리 130, 140, 150mm, 정식속도 45, 50, 55, 60No/min, 토양수 분함유량 10, 20, 30%, 토양 관수 후 경과 일 수 1, 2, 3, 4일로 하였다. 시험결과 정식률은 주간거리 140mm와 정식속도 50∼55No/min에서 100%로 가장 높게 나타났다. 식부자세는 사질양토에서 주간거리 140mm, 정식속도 50No/min일때 평균 11.2±13.9°로 가장 안정적인 자세로 정식하였고 개공폭은 38.2±1.9mm로 가장 작게 나타나 식부개공기 직경 34mm보다 4.2mm밀림이 나타났다. 최대하중평균은 정식속도 60No/min, 주간거리 150mm일때 45.1±5.1N로 나타났고, 최대정식동력은 124.2±11.8W로 나 타났다. 토양수분함유량은 30%일때 가장 낮았고, 관수 후 1일차가 가장 낮았다. 개선된 4절링크-캠 방 식 식부장치는 주간거리 140mm에 맞는 캠 형상을 갖게 함으로서 개공기-토양 상대속도가 0이 될 수 있었다. 따라서 본 양파정식기 식부장치는 필요 주간거리에 맞추어 상대속도 0의 캠 형상을 갖게 함으 로서 식부성능을 최대화할 수 있는 것으로 판단된다.

Pick-up truck has the advantage that can transport more baggage by the deck. However, it is inconvenient to put loads by a high ground clearance values. In this paper, we proposed a corresponding method to the high ground clearance using 4-bar linkage lift mechanism of tailgate. In addition, the validity of the lift mechanism through the prototype test is verified.

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.