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이청화,주백석 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.2
The experimental results are presented of an autonomous flight algorithm of a foldable quadcopter withairdrop launching functions. A foldable wing structure enabled the quadcopter to be inserted into a rocketcontainer with limited space. The foldable quadcopter was then separated from the rocket in the air. Theflight pattern was tracked using a global positioning system (GPS) with various sensors, including an inertialmeasurement unit (IMU) module until a designated target position was reached. Extensive field tests wereconducted through an international rocket competition, ARLISS 2017, which was held in Black Rock Desert,Nevada, USA. The flight trajectory record of the experiments is stored in electrically erasable programmableread-only memory (EEPROM) embedded in the main control unit. The flight record confirmed that thequadcopter successfully separated from the rocket, executed flight toward the target for a certain length oftime, and stably landed on the ground.
Three-Modular Obstacle-Climbing Robot for Cleaning Windows on Building Exterior Walls
이청화,주백석 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.8
In this research, a three-modular obstacle-climbing robot is suggested for the operation of a window-cleaning system on the façade of buildings. The suggested robot is composed of a main platform and three modular climbing units. The middle module has the window-cleaning system that performs the cleaning task using a roll-brush, water and detergent, a squeezing pad, and a suction device. Various sensors are installed in each climbing module to detect obstacles and measure the states of the robot and the wall. A winch mechanism is set on the top of the building to facilitate the vertical motion of the robot. The robot controller coordinates the three modules as well as the winch to climb obstacles. To evaluate the performance of the developed robot prototype, a 6-m-high test bed was set up on the roof and the façade. The obstacle size and time required to climb the obstacle were selected as the performance indices. In addition, quantitative and qualitative evaluation of the window-cleaning system were performed. As a result, it was confirmed that the obstacle-climbing robot could climb obstacles of varying sizes with reasonable speed while it performed the window-cleaning function. This research shows that a systemically well designed robot with a combination of simple sensors and actuators can solve the practical problem and apply in built buildings.
이청화,강환희,주백석 제어·로봇·시스템학회 2019 제어·로봇·시스템학회 논문지 Vol.25 No.6
One of the major disadvantages of the unmanned aircraft such as a drone is that it has finite capacity of the battery and it is almost impossible to change the battery during the flight. In order to overcome the drawback, this research proposes a novel airdrop operation with dual unmanned aircraft. The suggested dual unmanned aircraft is composed of a carrier octo-copter and a mission quad-copter. The carrier octo-copter with large payload carries the mission quad-copter and flies with its energy source. After fully consuming the energy, the carrier octo-copter drops the mission quad-copter in the air. Then, the mission quad-copter starts to operate its designated mission with its own energy source. To enable the airdrop operation, a foldable structure of the mission quad-copter was developed. Intensive experiments to verify this airdrop flight mechanism were carried out with autonomous flight-back to the destination. The position and altitude data during experiments were acquired using the GPS and barometer in the quad-copter flight control unit. Synthesizing the information from the experiments, it is confirmed that the suggested idea can be a promising alternative to enlarge the flight distance and duration of the unmanned aircraft.
자율주행 단계 4+ 자율주행차를 위한 엣지 기반 Fallback 기법
이청화(Cheonghwa Lee),옥기수(Kisu Ok),신승륜(Seungryun Shin),홍성수(Seongsoo Hong) 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.11
자율주행차의 fallback 기법은 주행 중 발생하는 위험상황에 대응하는 회피기동기술 중의 하나이다. 자율주행 단계 4+를 구현하려면 이러한 회피기동기술을 적용하는 것이 필수적이지만, 이는 매우 어려운 일이다. 주행 중에 발생하는 위험상황의 경우의 수가 매우 많고, 각 경우에 대해 최적의 대응기동방법을 선택하는 연구가 부재하기 때문이다. 본 연구에서는 이를 극복하기 위해 위험사항의 경우의 수를 유한하게 한정시키고, 각 위험상황마다 최적의 대응책을 선택할 수 있는 체계적인 기법을 개발하여, 이를 road-side 엣지에 적용한다. 먼저 위험사항들을 분류하기 위해, ego-vehicle 을 기준으로 기동구역을 특정하고 그 구역을 다시 하부구역으로 나눈 뒤, 위험요소가 있는 경우와 없는 경우로 양분하여 전체 위험상황의 수를 한정한다. 이렇게 도출된 전체 위험상황들 각각에 대해 휴리스틱을 사용하여 최적의 대응기동방법을 도출한다. 그 결과로 위험상황과 최적의 대응기동으로 맺어진 튜플(tuple)들이 생성되는데, 이들은 총체적으로 시스템 튜플 스페이스(tuple space)를 구성하게 된다. 이 튜플 스페이스는 fallback 룰베이스가 되며, 엣지에 위치하여 엣지가 주변 차량을 관제하는데 사용된다. 제안된 기법을 우리는 엣지 기반 fallback 기법이라 부른다.
이청화(Cheonghwa Lee),주백석(Baeksuk Chu) 한국기계가공학회 2017 한국기계가공학회지 Vol.16 No.2
This paper introduces a novel obstacle-climbing robot that moves on the facade of buildings and its climbing mechanism. A winch system set on the top of the building makes the vertical motion of the robot while it climbs obstacles that protrude from the wall surface. The obstacle-climbing robot suggested in this research is composed of a main platform and three modular climbing units. Various sensors installed on each climbing unit detect the obstacles, and the robot controller coordinates the three units and the winch to climb the obstacles using the obstacle-climbing mechanism. To evaluate the performance of the developed robot prototype, a test bed, which consists of an artificial wall and an obstacle, was manufactured. The obstacle size and the time required to climb the obstacle were selected as the performance indices, and extensive experiments were carried out. As a result, it was confirmed that the obstacle-climbing robot can climb various-sized obstacles with a reasonable speed while it moves on the wall surface.