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

An Active Uprighting Mechanism for Flying Robots

Flying robots have unique advantages in the exploration of cluttered environments such as caves or collapsed buildings. Current systems however have difficulty in dealing with the large amount of obstacles inherent to such environments. Collisions with obstacles generally result in crashes from which the platform can no longer recover. This paper presents a method for designing active uprighting mechanisms for protected rotorcraft-type flying robots that allow them to upright and subsequently take off again after an otherwise mission-ending collision. This method is demonstrated on a tailsitter flying robot which is capable of consistently uprighting after falling on its side using a spring-based ’leg’ and returning to the air to continue its mission

The AirBurr: A Flying Robot That Can Exploit Collisions

Research made over the past decade shows the use of increasingly complex methods and heavy platforms to achieve autonomous flight in cluttered environments. However, efficient behaviors can be found in nature where limited sensing is used, such as in insects progressing toward a light at night. Interestingly, their success is based on their ability to recover from the numerous collisions happening along their imperfect flight path. The goal of the AirBurr project is to take inspiration from these insects and develop a new class of flying robots that can recover from collisions and even exploit them. Such robots are designed to be robust to crashes and can take-off again without human intervention. They navigate in a reactive way and, unlike conventional approaches, they don't need heavy modelling in order to fly autonomously. We believe that this new paradigm will bring flying robots out of the laboratory environment and allow them to tackle unstructured, cluttered environments. This paper aims at presenting the vision of the AirBurr project, as well as the latest results in the design of a platform capable of sustaining collisions and self-recovering after crashes

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

Spacecraft/Rover Hybrids for the Exploration of Small Solar System Bodies

This study investigated a novel mission architecture for the systematic and affordable in-situ exploration of small Solar System bodies. Specifically, a mother spacecraft would deploy over the surface of a small body one, or several, spacecraft/rover hybrids, which are small, multi-faceted enclosed robots with internal actuation and external spikes. They would be capable of 1) long excursions (by hopping), 2) short traverses to specific locations (through a sequence of controlled tumbles), and 3) high-altitude, attitude-controlled ballistic flight (akin to spacecraft flight). Their control would rely on synergistic operations with the mother spacecraft (where most of hybrids' perception and localization functionalities would be hosted), which would make the platforms minimalistic and, in turn, the entire mission architecture affordable

Spacecraft/Rover Hybrids for the Exploration of Small Solar System Bodies

This study investigated a mission architecture that allows the systematic and affordable in-situ exploration of small solar system bodies, such as asteroids, comets, and Martian moons (Figure 1). The architecture relies on the novel concept of spacecraft/rover hybrids,which are surface mobility platforms capable of achieving large surface coverage (by attitude controlled hops, akin to spacecraft flight), fine mobility (by tumbling), and coarse instrument pointing (by changing orientation relative to the ground) in the low-gravity environments(micro-g to milli-g) of small bodies. The actuation of the hybrids relies on spinning three internal flywheels. Using a combination of torques, the three flywheel motors can produce a reaction torque in any orientation without additional moving parts. This mobility concept allows all subsystems to be packaged in one sealed enclosure and enables the platforms to be minimalistic. The hybrids would be deployed from a mother spacecraft, which would act as a communication relay to Earth and would aid the in-situ assets with tasks such as localization and navigation (Figure 1). The hybrids are expected to be more capable and affordable than wheeled or legged rovers, due to their multiple modes of mobility (both hopping and tumbling), and have simpler environmental sealing and thermal management (since all components are sealed in one enclosure, assuming non-deployable science instruments). In summary, this NIAC Phase II study has significantly increased the TRL (Technology Readiness Level) of the mobility and autonomy subsystems of spacecraft/rover hybrids, and characterized system engineering aspects in the context of a reference mission to Phobos. Future studies should focus on improving the robustness of the autonomy module and further refine system engineering aspects, in view of opportunities for technology infusion

Design of Flying Robots for Collision Absorption and Self-Recovery

Flying robots have the unique advantage of being able to move through the air unaffected by the obstacles or precipices below them. This ability quickly becomes a disadvantage, however, as the amount of free space is reduced and the risk of collisions increases. Their sensitivity to any contact with the environment have kept them from venturing beyond large open spaces and obstacle-free skies. Recent efforts have concentrated on improving obstacle detection and avoidance strategies, modeling the environment and intelligent planning to navigate ever tighter spaces while remaining airborne. Though this strategy is yielding impressive and improving results, it is limited by the quality of the information that can be provided by on-board sensors. As evidenced by insects that collide with windows, there will always be situations in which sensors fail and a flying platform will collide with the obstacles around it. It is this fact that inspired the topic of this thesis: enabling flying platforms to survive and recover from contact with their environment through intelligent mechanical design. There are three main challenges tackled in this thesis: robustness to contact, self-recovery and integration into flight systems. Robustness to contact involves the protection of fast-spinning propellers, the stiff inner frame of a flying robot and its embedded sensors from damage through the elastic absorption of collision energy. A method is presented for designing protective structures that transfer the lowest possible amount of force to the platform's frame while simultaneously minimizing weight and thus their effect on flight performance. The method is first used to design a teardrop-shaped spring configuration for absorbing head-on collisions typically experienced by winged platforms. The design is implemented on a flying platform that can survive drops from a height of 2 m. A second design is then presented, this time using springs in a tetrahedral configuration that absorb energy through buckling. When embedded into a hovering platform the tetrahedral protective mechanisms are able to absorb dozens of high-speed collisions while significantly reducing the forces on the platforms frame compared to foam-based protection typically used on other platforms. Surviving a collision is only half of the equation and is only useful if a flying platform can subsequently return to flight without requiring human intervention, a process called self-recovery. The theory behind self-recovery as it applies to many types of flying platforms is first presented, followed by a method for designing and optimizing different types of self-recovery mechanisms. A gravity-based mechanism is implemented on an ultra-light (20.5 g) wing-based platform whose morphology and centre of gravity are optimized to always land on its side after a collision, ready to take off again. Such a mechanism, however, is limited to surfaces that are flat and obstacle-free and requires clear space in front of the platform to return to the air. A second, leg-based self-recovery mechanism is thus designed and integrated into a second hovering platform, allowing it to upright into a vertical takeoff position. The mechanism is successful in returning the platform to the air in a variety of complex environments, including sloped surfaces, corners and surface textures ranging from smooth hardwood to gravel and rocks. In a final chapter collision energy absorption and self-recovery mechanisms are integrated into a single hovering platform, the first example of a flying robot capable of crashing into obstacles, falling to the ground, uprighting and returning to the air, all without human intervention. These abilities are first demonstrated through a contact-based random search behaviour in which the platform explores a small enclosed room in complete darkness. After each collision with a wall the platform falls to the ground, recovers and then continues exploring. In a second experiment the platform is programmed with a basic phototaxis behaviour. Using only four photodiodes that provide a rough idea of the bearing to a source of light the platform is able to consistently cross a 13x2.2mcorridor and traverse a doorway without using any obstacle avoidance, modeling or planning

A Biologically Inspired Jumping and Rolling Robot

Mobile robots for rough terrain are of interest to researchers as their range of possible uses is large, including exploration activities for inhospitable areas on Earth and on other planets and bodies in the solar system, searching in disaster sites for survivors, and performing surveillance for military applications. Nature generally achieves land movement by walking using legs, but additional modes such as climbing, jumping and rolling are all produced from legs as well. Robotics tends not to use this integrated approach and adds additional mechanisms to achieve additional movements. The spherical device described within this thesis, called Jollbot, integrated a rolling motion for faster movement over smoother terrain, with a jumping movement for rougher environments. Jollbot was developed over three prototypes. The first achieved pause-and-leap style jumps by slowly storing strain energy within the metal elements of a spherical structure using an internal mechanism to deform the sphere. A jump was produced when this stored energy was rapidly released. The second prototype achieved greater jump heights using a similar structure, and added direction control to each jump by moving its centre of gravity around the polar axis of the sphere. The final prototype successfully combined rolling (at a speed of 0.7 m/s, up 4° slopes, and over 44 mm obstacles) and jumping (0.5 m cleared height), both with direction control, using a 0.6 m spherical spring steel structure. Rolling was achieved by moving the centre of gravity outside of the sphere’s contact area with the ground. Jumping was achieved by deflecting the sphere in a similar method to the first and second prototypes, but through a larger percentage deflection. An evaluation of existing rough terrain robots is made possible through the development of a five-step scoring system that produces a single numerical performance score. The system is used to evaluate the performance of Jollbot.EThOS - Electronic Theses Online ServiceGBUnited Kingdo