방향 전환, 도약 각도 조절, 자세 교정이 가능한 점핑 로봇

학위논문 (석사)-- 서울대학교 대학원 : 공과대학 기계항공공학부, 2019. 2. 조규진.도약 로봇은 로봇 자신의 크기보다 큰 장애물을 넘어 이동할 수 있다. 도약 운동만으로 원하는 위치에 도달하기 위해 도달 가능한 범위를 넓힐 수 있는 방향 전환, 도약 각도 조절, 자세 교정 기능이 통합된 점핑 로봇들이 개발됐다. 이 때 추가 기능을 통합하면 로봇의 질량이 증가하고 도약 성능이 감소하므로 질량을 줄이기 위한 설계가 필요하다. 본 논문에서는 방향 전환, 도약 각도 조절, 자세 교정이 가능한 도약 로봇을 제안하며, 도약 성능 감소를 최소화하기 위해 메커니즘과 구동기를 공유할 수 있도록 로봇이 설계되었다. 로봇의 질량은 70.1 g으로 최대 높이 1.02 m, 최대 거리 1.28 m를 도약할 수 있다. 또한, 전 방향으로 도약할 수 있으며, 반복 도약으로 더 먼 곳에 도달할 수 있다. 로봇의 거동을 예측할 수 있는 동역학 모델을 세웠으며, 미끄러짐이 없이 도약하는 경우뿐만 아니라 미끄러짐이 포함된 도약에 대해서도 로봇의 거동을 확인하고 도약 궤적을 계획할 수 있다. 구동기의 수보다 많은 기능의 수를 구현하는 설계 방법은 다른 소형 로봇의 설계에 적용할 수 있을 것이다. 이 로봇은 비정형 환경에서 수색, 정찰 혹은 탐사와 같은 임무를 수행하는 데 활용 가능할 것이다.Jumping enables the robot to overcome obstacles that are larger than its own size. In order to reach the desired location with only jumping, the jumping robots integrated with additional functions –steering, adjusting the take-off angle, and self-righting – have been developed to expand the reachable range of the robot. Design to reduce mass is required as the integration of additional functions increases the mass of the robot and reduces the jumping performance. In this thesis, a jumping robot capable of steering, adjusting the take-off angle, and self-righting is proposed with the design of actuator and mechanism sharing to minimize the jumping performance degradation. The robot, with a mass of 70.1 g jumps up to 1.02 m in vertical height, and 1.28 m in horizontal distance. It can change the jumping height and distance by adjusting the take-off angle from 40° to 91.9°. The robot can jump in all directions, and it can reach farther through multiple jumps. A dynamic model is established to predict the behavior of the robot and plan the jumping trajectory not only for jumping without slip but also for jumping with slip. The design method to implement more functions than the number of actuators can be applied to design other small-scale robots. This robot can be deployed to unstructured environments to perform tasks such as search and rescue, reconnaissance, and exploration.Abstract ⅰ Contents ⅲ List of Tables ⅴ List of Figures ⅵ Chapter 1. Introduction 1 1.1. Motivation 1 1.2. Research Objectives and Contributions 3 1.3. Research Overview 6 Chapter 2. Design 7 2.1. Jumping 8 2.2. Steering 10 2.3. Take-off Angle Adjustment 12 2.4. Self-Righting 13 2.5. Integration 16 Chapter 3. Analysis 19 3.1. Dynamic Modeling 19 3.2. Simulated Results 24 3.3. Jumping Trajectory Planning 33 Chapter 4. Result 35 4.1. Performance 35 4.2. Demonstration 40 Chapter 5. Conclusion 46 Bibliography 49 국문 초록 53Maste

Exploiting the Nonlinear Stiffness of Origami Folding to Enhance Robotic Jumping Performance

This research investigates the effects of using origami folding techniques to develop a nonlinear jumping mechanism with optimized dynamic performance. A previous theoretical investigation has shown the benefits of using a nonlinear spring element compared to a linear spring for improving the dynamic performance of a jumper. This study sets out to experimentally verify the effectiveness of utilizing nonlinear stiffness to achieve optimized jumping performance. The Tachi-Miura Polyhedron (TMP) origami structure is used as the nonlinear energy-storage element connecting two end-point masses. The TMP bellow exhibits a “strain-softening” nonlinear force-displacement behavior resulting in an increased energy storage compared to a linear spring. The geometric parameters of the structure are optimized to improve air-time and maximum jumping height. An additional TMP structure was designed to exhibit a close-to-linear force-displacement response to serve as the representative linear spring element. A critical challenge in this study is to minimize the hysteresis and energy loss of TMP during its compression stage before jumping. To this end, plastically annealed lamina emergent origami (PALEO) concept is used to modify the creases of the structure in order to reduce hysteresis during the compression cycle. PALEO works by increasing the folding limit before plastic deformation occurs, thus improving the energy retention of the structure. Steel shim stock are secured to the facets of the TMP structure to serve as end-point masses, and the air-time and jumping height of both structures are measured and compared. The nonlinear TMP structure achieves roughly 9% improvement in air-time and a 12% improvement in jumping height when compared to the linear TMP structure. These results validate the theoretical benefits of utilizing nonlinear spring elements in jumping mechanisms and can lead to improved performance in dynamic systems which rely on springs as a method of energy storage and can lead to emergence of a new generation of more efficient jumping mechanisms with optimized performance in the future

Using Origami Folding Techniques to Study the Effect of Non-Linear Stiffness on the Performance of Jumping Mechanism

This research uses Origami patterns and folding techniques to generate non-linear force displacement profiles and study their effect on jumping mechanisms. In this case, the jumping mechanism is comprised of two masses connected by a Tachi-Miura Polyhedron (TMP) with non-linear stiffness characteristics under tensile and compressive loads. The strain-softening behavior exhibited by the TMP enables us to optimize the design of the structure for improved jumping performance. I derive the equations of motion of the jumping process for the given mechanism and combine them with the kinematics of the TMP structure to obtain numerical solutions for the optimum design. The results correlate to given geometric configurations for the TMP that result in the two optimum objectives: The maximum time spent in the air and maximum clearance off the ground. I then physically manufacture the design and conduct compression tests to measure the force-displacement response and confirm it with the theoretical approach based on the kinematics. Experimental data from the compression tests show a hysteresis problem where the force-displacement profile exhibits different behavior whether the structure is being compressed or released. I investigate two methods to nullify the hysteresis when compressing or releasing the mechanism and then discuss their results. This research can lead to easily manufacturable jumping robotic mechanisms with improved energy storage and jumping performance. Additionally, I learn more about how to use origami techniques to harness unique stiffness properties and apply them to a variety of scenarios