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학위논문 (박사)-- 서울대학교 대학원 공과대학 기계항공공학부, 2017. 8. 김종원.고층빌딩은 점차 높아지고 있고 그 수가 증가하고 있지만 건물 유지보수를 위해 필요한 외벽 청소는 작업자의 수작업에 의존하고 있다. 작업자는 위험에 항상 노출되어 있으며 매년 인명피해가 발생하고 있다. 따라서 작업자의 안전을 보장하고 작업의 효율성을 높이기 위해 외벽 청소 작업을 로봇으로 대체하고자 하는 연구가 꾸준히 이루어지고 있다. 본 논문은 다양한 외벽의 형상에 적용 가능하고 작업의 확장이 용이한 모듈형 구조의 외벽 청소 로봇을 제시한다. 등반 로봇 플랫폼은 외벽에 부착되어 등하강이 가능하며 모듈형 결합부를 통해 청소 유닛의 탈부착이 용이한 구조이다. 청소유닛은 건식 청소 유닛과 반습식 청소 유닛 두 가지가 개발되었으며 청소면의 종류, 오염도에 따라 교체하여 사용할 수 있다. 청소유닛은 볼스크류 매커니즘을 통해 등반 방향의 수직한 면으로 2 자유도의 움직임이 가능하며 벽면과의 거리나 각도가 달라질 때 적응이 가능하다. 청소유닛 작업영역의 양 끝에는 반력을 측정할 수 있는 센서가 장착되었으며 청소 성능을 일정하게 유지하기 위하여 반력을 일정하게 유지할 수 있는 힘 제어 알고리즘이 필수적이다. 청소유닛의 힘 제어는 위치 기반의 간접 제어 방식인 임피던스 제어 구조를 사용하여 구현하였다. 또한 전체 제어기는 힘 추종 임피던스 제어기에 외란 관측기와 슬라이딩 모드 제어기를 결합하였다. 제어기 목표는 등반 로봇 플랫폼과 벽면간의 거리 변화와 청소유닛 브러쉬의 회전으로 인해 생기는 외란, 시스템 파라미터의 오차로 인해 생기는 외란을 보상하는 것이다. 외란 관측기는 청소유닛과 주위 환경과의 상호작용 모델링을 기반으로 목표 힘과 실제 힘과의 차이에 대한 보상 입력을 도출하고 슬라이딩 모드 제어는 모델링 되지 않은 외란에 대해서 보상하는 역할을 한다. 설계된 전체 제어기에 대해서 안정성을 해석하고 시뮬레이션을 통하여 설계한 제어기의 타당성을 검증한다. 실제 외벽에서의 작업을 재현하기 위한 테스트벤치를 제작하고 실제 청소유닛에 적용하여 실험을 수행함으로써 설계된 제어기의 외란 제거 성능을 확인하였다.As a lot of high-rise buildings have been recently constructed, demand of systematic and regular operations for their maintenances/inspections has been increasing. Among those operations, wall-cleaning is the most popular and frequently required task. Unfortunately, since most of wall-cleanings are performed by human operators using ropes or lifts, there is always a possibility of unexpected accidents. These accidents can be the result of workers carelessness or undesired disturbances like winds and obstacles on walls. Therefore many researches have been going on to replace human workers by robots, developing various types of mobile platforms that can clean up the wall of building perfectly and safely. This paper presents a modular wall cleaning robot that can be applied to various building shapes and can extend its operating function. The wall-climbing platform can climb up/down various types of walls with the help of the rope ascender and two propeller thrusters. And the cleaning unit can be easily attached and detached through the modular coupling part. Two types of cleaning units have been developed, a dry type cleaning unit and a semi-wet type cleaning unit, which can be replaced according to the types of the surface and the level of pollutant. The cleaning unit has two degrees of freedom on the perpendicular plane to the climbing direction. And the cleaning unit can adjust angle and distance to the wall by ball screw mechanism. In order to maintain the constant cleaning performance, a force tracking control algorithm is applied. Therefore, a sensor measuring the reaction force is mounted on both ends of the cleaning unit. The force control of the cleaning unit uses impedance control. Overall control system consists of position-based force tracking impedance controller, disturbance observer and sliding mode controller. The objective of these controllers is to compensate the disturbance, caused by change of distance between the climbing robot platform and the wall, rotation of the cleaning unit brush and the system parameter error. The disturbance observer compensation control input is calculated from the difference of desired force and actual force based on the interaction dynamic model between the cleaning unit and the surrounding condition. And the sliding mode control compensates the disturbance from mismatched uncertainties. The stability analysis of overall control system is derived and the performance analysis of the controller is carried out through simulations. The performance and stability of the proposed controller is verified with experiments in the test bench reflecting the actual field condition.Abstract i Contents iii List of Figures vii 1. Introduction 1 1.1 Motivation 1 1.2 Previous research 2 1.3 Objective and scope 5 2. Development of ROPE RIDE 7 2.1 ROPE RIDE concept 7 2.2 Mechanical design 8 2.2.1 Wall climbing platform 8 2.2.2 Modular cleaning unit 10 2.2.3 Hardware architectures of wall-climbing platform and cleaning unit 14 2.3 Optimization of operating conditions for wall-claeaning unit 16 2.4 Experiments 23 3. Modeling of modular cleaning unit 29 3.1 Description of kinematics model 29 3.2 Description of dynamic model 32 4. Design of force tracking algorithm 34 4.1 Position-based force tracking impedance control 34 4.1.1 Position-based force tracking impedance controller design 37 4.1.2 Stability and performance analysis 41 4.1.3 Force tracking impedance controller gain tuning using root locus 42 4.2 Disturbance Compensation algorithm 45 4.2.1 Disturbance observer design 45 4.2.1.1 System identification of cleaning unit 48 4.2.1.2 Q-filter design of disturbance observer 51 4.2.1.3 Stability analysis of disturbance observer 52 4.2.1.4 Stability analysis of whole control system 54 4.2.1.5 Performance analysis 57 4.2.2 Sliding mode controller design 60 4.2.2.1 Sliding surface design 60 4.2.2.2 Stability analysis 62 5. Simulations and Experiments 64 5.1 Measurement of disturbances 64 5.1.1 Disturbance from external wall and robotic platform 64 5.1.2 Disturbance from cleaning unit 66 5.2 Simulations 69 5.3 Experiments 75 6. Conclusion 82 Bibliography 84 Abstract in Korean 86Docto

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