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

The jumping mechanism of flea beetles (Coleoptera, Chrysomelidae, Alticini), its application to bionics and preliminary design for a robotic jumping leg

Flea beetles (Coleoptera, Chrysomelidae, Galerucinae, Alticini) are a hyperdiverse group of organisms with approximately 9900 species worldwide. In addition to walking as most insects do, nearly all the species of flea beetles have an ability to jump and this ability is commonly understood as one of the key adaptations responsible for its diversity. Our investigation of flea beetle jumping is based on high-speed filming, micro- CT scans and 3D reconstructions, and provides a mechanical description of the jump. We reveal that the flea beetle jumping mechanism is a catapult in nature and is enabled by a small structure in the hind femur called an ‘elastic plate’ which powers the explosive jump and protects other structures from potential injury. The explosive catapult jump of flea beetles involves a unique ‘high-efficiency mechanism’ and ‘positive feedback mechanism’. As this catapult mechanism could inspire the design of bionic jumping limbs, we provide a preliminary design for a robotic jumping leg, which could be a resource for the bionics industry

Impact of Different Developmental Instars on Locusta migratoria Jumping Performance

Ontogenetic locomotion research focuses on the evolution of locomotion behavior in different developmental stages of a species. Unlike vertebrates, ontogenetic locomotion in invertebrates is poorly investigated. Locusts represent an outstanding biological model to study this issue. They are hemimetabolous insects and have similar aspects and behaviors in different instars. This research is aimed at studying the jumping performance of Locusta migratoria over different developmental instars. Jumps of third instar, fourth instar, and adult L. migratoria were recorded through a high-speed camera. Data were analyzed to develop a simplified biomechanical model of the insect: the elastic joint of locust hind legs was simplified as a torsional spring located at the femur-tibiae joint as a semilunar process and based on an energetic approach involving both locomotion and geometrical data. A simplified mathematical model evaluated the performances of each tested jump. Results showed that longer hind leg length, higher elastic parameter, and longer takeoff time synergistically contribute to a greater velocity and energy storing/releasing in adult locusts, if compared to young instars; at the same time, they compensate possible decreases of the acceleration due to the mass increase. This finding also gives insights for advanced bioinspired jumping robot design

Investigating Energetic Porous Silicon as a Solid Propellant Micro-Thruster

Energetic porous silicon has emerged as a novel on-chip energetic material capable of generating thrust that can be harnessed for positioning of millimeter and micron-scale mobile platforms such as microrobots and nano-satellites. Porous silicon becomes reactive when nano-scale pores are infused with an oxidizer such as sodium perchlorate. In this work, energetic porous silicon was investigated as a means of propulsion by quantifying thrust and impulse produced during the exothermic reaction as a function of porosity. The baseline porous silicon devices were two millimeter diameter and etched to a target depth of 25 microns. As a result of changing porosity, a 7x increase in thrust performance and a 16x increase in impulse performance was demonstrated. The highest thrust and impulse values measured were 680 mN and 266 micron Newton seconds respectively from a 2 mm diameter porous silicon device with 72 % porosity. Limitations and trade-offs associated with arrays of devices were presented by studying the effects of scaling porous silicon area, and characterizing thrust when arrays of porous silicon micro-thruster devices were ignited simultaneously. In addition, the effects of sympathetic ignition were evaluated to better understand how closely independent devices could be physically spaced on a 1 cm2 chip. 3D nozzles were fabricated to study confinement effects by varying nozzle throat diameter, and divergent angle. It was shown that integration of a nozzle (throat diameter of 0.75 mm and a divergent angle of theta = 10 degrees) resulted in approximately 4X increase in thrust, and 4X increase in impulse. This study highlighted enhancements to thrust and impulse generated by porous silicon, identified trade-offs associated with simultaneous activation of multiple devices on a 1 cm2 chip, and showed energetic porous silicon as a viable solid propellant for propulsion of nano-satellites and micro-robots

Design of high-performance legged robots: A case study on a hopping and balancing robot

The availability and capabilities of present-day technology suggest that legged robots should be able to physically outperform their biological counterparts. This thesis revolves around the philosophy that the observed opposite is caused by over-complexity in legged robot design, which is believed to substantially suppress design for high-performance. In this dissertation a design philosophy is elaborated with a focus on simple but high performance design. This philosophy is governed by various key points, including holistic design, technology-inspired design, machine and behaviour co-design and design at the performance envelope. This design philosophy also focuses on improving progress in robot design, which is inevitably complicated by the aspire for high performance. It includes an approach of iterative design by trial-and-error, which is believed to accelerate robot design through experience. This thesis mainly focuses on the case study of Skippy, a fully autonomous monopedal balancing and hopping robot. Skippy is maximally simple in having only two actuators, which is the minimum number of actuators required to control a robot in 3D. Despite its simplicity, it is challenged with a versatile set of high-performance activities, ranging from balancing to reaching record jump heights, to surviving crashes from several meters and getting up unaided after a crash, while being built from off-the-shelf technology. This thesis has contributed to the detailed mechanical design of Skippy and its optimisations that abide the design philosophy, and has resulted in a robust and realistic design that is able to reach a record jump height of 3.8m. Skippy is also an example of iterative design through trial-and-error, which has lead to the successful design and creation of the balancing-only precursor Tippy. High-performance balancing has been successfully demonstrated on Tippy, using a recently developed balancing algorithm that combines the objective of tracking a desired position command with balancing, as required for preparing hopping motions. This thesis has furthermore contributed to several ideas and theories on Skippy's road of completion, which are also useful for designing other high-performance robots. These contributions include (1) the introduction of an actuator design criterion to maximize the physical balance recovery of a simple balancing machine, (2) a generalization of the centre of percussion for placement of components that are sensitive to shock and (3) algebraic modelling of a non-linear high-gravimetric energy density compression spring with a regressive stress-strain profile. The activities performed and the results achieved have been proven to be valuable, however they have also delayed the actual creation of Skippy itself. A possible explanation for this happening is that Skippy's requirements and objectives were too ambitious, for which many complications were encountered in the decision-making progress of the iterative design strategy, involving trade-offs between exercising trial-and-error, elaborate simulation studies and the development of above-mentioned new theories. Nevertheless, from (1) the resulting realistic design of Skippy, (2) the successful creation and demonstrations of Tippy and (3) the contributed theories for high-performance robot design, it can be concluded that the adopted design philosophy has been generally successful. Through the case study design project of the hopping and balancing robot Skippy, it is shown that proper design for high physical performance (1) can indeed lead to a robot design that is capable of physically outperforming humans and animals and (2) is already very challenging for a robot that is intended to be very simple