Mechanical Design and Locomotion of Modular-Expanding Robots

Engineering and Applied SciencesOther Research Uni

A new meta-module for efficient reconfiguration of hinged-units modular robots

We present a robust and compact meta-module for edge-hinged modular robot units such as M-TRAN, SuperBot, SMORES, UBot, PolyBot and CKBot, as well as for central-point-hinged ones such as Molecubes and Roombots. Thanks to the rotational degrees of freedom of these units, the novel meta-module is able to expand and contract, as to double/halve its length in each dimension. Moreover, for a large class of edge-hinged robots the proposed meta-module also performs the scrunch/relax and transfer operations required by any tunneling-based reconfiguration strategy, such as those designed for Crystalline and Telecube robots. These results make it possible to apply efficient geometric reconfiguration algorithms to this type of robots. We prove the size of this new meta-module to be optimal. Its robustness and performance substantially improve over previous results.Peer ReviewedPostprint (author's final draft

Разработка устройства сопряжения для модульной сельскохозяйственной робототехнической платформы

To create multifunctional robotic platforms for agricultural use, it is reasonable to use a modular principle that will allow installing various equipment depending on the tasks assigned to the robotic tool. Providing autonomous reconfiguration capabilities will reduce human interference and maintenance costs. (Research purpose) This work is aimed at developing a scalable device for interfacing functional modules with the agricultural robotic base platform, which can provide mechanical fixation, energy transfer and information exchange. (Materials and methods) This article analyzes the previous research into the solutions for interfacing modules in robotic complexes and points out their benefits and drawbacks. Based on the analysis and own research, the interface mechanism structure was developed to ensure the correct mutual position and fixation of the module to the base platform under the assumption of possible energy and information exchange. (Results and discussion) In the course of the work, the design ratios for the interface device were derived, making it possible to calculate the permissible linear displacements and permissible angular deviation of the mechanism interfacing elements. Based on the permissible linear deviations up to 10-13 millimeters and a permissible angular deviation of 20 degrees, the main dimensions of the device prototype were obtained. A prototype interface device was operationalized with the dimensional specifications of 200 millimeters in length, 130 millimeters in width, 58 millimeters in height. Several experiments with the device prototype were carried out based on various linear and angular deviations of the interfacing elements. (Conclusions) It was found out that successful interfacing occurs in 98 percent of cases subject to admissible calculated displacements. It was concluded that the proposed interface device will allow for the autonomous replacement of modules of multifunctional robotic platforms.Показали, что для создания многофункциональных робототехнических платформ сельскохозяйственного применения актуально использовать модульный принцип, который позволит устанавливать различное навесное оборудование в зависимости от задач, поставленных перед робототехническим средством. Отметили, что автономная реконфигурация снизит вмешательство человека в эксплуатацию и затраты на обслуживание. (Цель исследования) Разработать масштабируемое устройство сопряжения функциональных модулей с базовой сельскохозяйственной робототехнической платформой, которое сможет обеспечить механическую фиксацию, передачу энергии и информационный обмен. (Материалы и методы) Провели анализ исследовательских работ в направлении решений для сопряжения модулей в робототехнических комплексах, отметили их достоинства и недостатки. Создали структуру механизма сопряжения для обеспечения корректного взаимного положения и фиксации модуля с базовой платформой при возможности энергетического и информационного обмена. (Результаты и обсуждение) Вывели расчетные соотношения для устройства сопряжения, позволяющие вычислять допустимые линейные смещения и допустимое угловое отклонение сопрягаемых элементов механизма. Определили основные размеры прототипа устройства по заданным допустимым линейными отклонениями в диапазоне до 10-13 миллиметров и с допустимым угловым отклонением 20 градусов. Реализовали прототип устройства сопряжения с габаритными размерами: длина – 200 миллиметров, ширина – 130, высота – 58 миллиметров. Провели с ним эксперименты, изменяя линейные и угловые отклонения сопрягаемых элементов. (Выводы) Определили, что успешное сопряжение происходит в 98 процентах случаев при соблюдении допустимых расчетных смещений. Заключили, что предложенное устройство сопряжения позволит реализовать автономную замену модулей многофункциональных робототехнических платформ

Modular and self-scalable origami robot: A first approach

This paper presents a proposal of a modular robot with origami structure. The proposal is based on a self-scalable and modular link made of soft parts. The kinematics of a single link and several links interconnected is studied and validated. Besides, the link has been prototyped, identified, and controlled in position. The experimental data show that the system meets the scalability requirements and that its response is totally reliable and robust.The research leading to these results has received funding from the project Desarrollo de articulaciones blandas para aplicaciones robóticas, with reference IND2020/IND-1739, funded by the Comunidad Autónoma de Madrid (CAM) (Department of Education and Research), and from RoboCity2030-DIH-CM, Madrid Robotics Digital Innovation Hub (Robótica aplicada a la mejora de la calidad de vida de los ciudadanos, FaseIV; S2018/NMT-4331), funded by “Programas de Actividades I+D en la Comunidad de Madrid” and cofunded by Structural Funds of the EU

Modular Self-Reconfigurable Robotic Systems: A Survey on Hardware Architectures

Modular self-reconfigurable robots present wide and unique solutions for growing demands in the domains of space exploration, automation, consumer products, and so forth. The higher utilization factor and self-healing capabilities are most demanded traits in robotics for real world applications and modular robotics offer better solutions in these perspectives in relation to traditional robotics. The researchers in robotics domain identified various applications and prototyped numerous robotic models while addressing constraints such as homogeneity, reconfigurability, form factor, and power consumption. The diversified nature of various modular robotic solutions proposed for real world applications and utilization of different sensor and actuator interfacing techniques along with physical model optimizations presents implicit challenges to researchers while identifying and visualizing the merits/demerits of various approaches to a solution. This paper attempts to simplify the comparison of various hardware prototypes by providing a brief study on hardware architectures of modular robots capable of self-healing and reconfiguration along with design techniques adopted in modeling robots, interfacing technologies, and so forth over the past 25 years

Kendi kendini konfigüre edebilen bir sistemdeki tekil modül için dış manyetik eyleyiciler kullanılarak hareket mekanizmasının geliştirilmesi

In microrobotics field, self-reconfigurable modular robots (SRMRs) offer several advantages including adaptation to uneven environments, the capability of handling various sets of tasks, and continuous operation in the case of a malfunction of a single module. The current research direction in self-reconfigurable robotic systems is towards reaching million level number of modules working in coherence by means of locomotion, self-reconfiguration, and information flow. This research direction comes with new challenges such as miniaturizing the modules. One should consider looking for alternative ways of locomotion and self-reconfiguration when dealing with SRMRs having million level number of modules. Externally actuating the modules can be a good alternative to micro SRMRs. In this study, we developed a novel motion mechanism for a single module in a micro SRMR system by using external magnetic actuators. An assembly of elastic microtubes and permanent magnets is attached inside a cube-shaped module and periodic motion of the assembly is applied. The motion of a single microtube with permanent magnets inside is generated by using COMSOL Multiphysics software. The results of the simulations are compared with theoretical values to validate the motion mechanism that is introduced in the study.Mikro robotik alanında, kendi kendini konfigüre edebilen modüler robotlar (KKMR) düzensiz çevreye uyum sağlayabilme, birçok değişken görevi yerine getirebilme ve tekil modüllerin arızalanması durumunda operasyonu sürdürebilme gibi avantajlar sunmaktadır. Kendi kendini konfigüre edebilen robotik sistemlerdeki son güncel araştırmalar, milyon seviyesinde modül sayısına sahip sistemlerin hareket, kendi kendini konfigüre etme ve bilgi akışı gözetilerek geliştirilmesi yönündedir. Bu araştırma yönelimi beraberinde modüllerin minyatürleştirilmesi gibi sınamalar getirmektedir. Milyon mertebesinde modüle sahip bir KKMR sistemi göz önünde bulundurulduğunda, hareket ve kendi kendini konfigüre etme mekanizmaları için alternatif metotların araştırılması gerekmektedir. Modüllerin dış eyleyiciler ile harekete geçirilmesi mikro KKMR sistemleri için iyi bir seçenek oluşturmaktadır. Bu çalışmada mikro KKMR sistemindeki tekil bir modül için dış manyetik eyleyiciler kullanılarak özgün bir hareket mekanizması geliştirilmiştir. Esnek mikro tüp ve kalıcı mıknatıslardan oluşan bir yapı modülün içerisine yerleştirilmiş ve yapıya periyodik bir hareket uygulanmıştır. Tekil bir mikro tüp kalıcı mıknatıs yapısının hareketi COMSOL Multiphysics yazılımı kullanılarak canlandırılmıştır. Simülasyon sonuçları teorik değerler ile karşılaştırılarak önerilen hareket mekanizmasının doğrulaması gerçekleştirilmiştir

가변 토폴로지 트러스 로봇의 안정적인 주행 알고리즘 개발

학위논문 (박사) -- 서울대학교 대학원 : 공과대학 기계공학과, 2020. 8. 김종원.Variable Topology Truss (VTT) is truss structured modular robot that can self-reconfigure its topology and geometric configuration, which can be usefully applied to rescuing work in disaster site. In this thesis, design of VTT is introduced and stable rolling locomotion algorithm for VTT is proposed. To achieve self-reconfiguration feature, VTT are composed specially designed members and nodes. VTTs members consist of Spiral Zippers which are novel linear actuators that has high extension ratio, light weight and high strength. VTTs nodes consist of Passive Member-Ends and Master Member-Ends. Passive Member-Ends are linkage type spherical joint with large angle range that can accommodate many members. Master Member-Ends are spherical manipulators that built in Sphere and it move member to change topology of VTT. Rolling locomotion of VTT is achieved by controlling the center of mass by geometric reconfiguration. However, the locomotion planning is complex problem, because VTT is parallel mechanism with high degree of freedom and many constraints, which makes it difficult to predict and avoid constraints for feasible planning. Thus, it needs stable algorithm that can find locomotion trajectory even in complicated and large environment. In addition, since VTT has many sophisticated components, the algorithm must prevent VTT being damaged from ground by tumbling. To meet the requirements, proposed locomotion algorithm is composed of 3 steps; support polygon planning, center of mass planning and node position planning. In support polygon planning, support polygon path is planned by newly proposed random search algorithm, Polygon-Based Random Tree (PRT). In center of mass planning, trajectory of desired projected center of mass is planned by maximizing stability feature. Planned support polygon path and center of mass trajectory guide VTT to have good-conditioned shape which configuration is far from constraints and makes locomotion planning success even in complex and large environment. In node position planning, Non-Impact Rolling locomotion algorithm was developed to plan position of VTTs nodes that prevent damage from the ground while following planned support polygon path and center of mass trajectory. The algorithm was verified by two case study. In case study 1, locomotion planning and simulation was performed considering actual constraints of VTT. To avoid collision between VTT and obstacle, safety space was defined and considered in support polygon planning. The result shows that VTT successfully reaches the goal while avoiding obstacles and satisfying constraints. In case study 2, locomotion planning and simulation was performed in the environment having wide space and narrow passage. Nominal length of VTT was set to be large in wide space to move efficiently, and set to be small in narrow passage to pass through it. The result shows that VTT successfully reaches the goal while changing its nominal length in different terrain.가변 토폴로지 트러스 (Variable Topology Truss, VTT)는 토폴로지와 기하학적 형상의 재구성이 가능한 트러스 구조의 모듈 로봇이다. 본 논문에서는 VTT의 설계 구조를 소개하고 VTT의 안정적인 주행을 알고리즘을 제안한다. VTT는 토폴로지와 기하학적 형상의 재구성을 위해 특수한 구조의 멤버와 노드를 가진다. VTT의 멤버는 높은 압축비, 가벼운 중량, 높은 강도를 가진 신개념 선형 구동기인 스파이럴 지퍼로 구성되어 있다. VTT의 노드는 패시브 멤버 엔드와 마스터 엔드로 구성되어 있다. 패시브 멤버는 링키지 구조의 3 자유도 관절로, 넓은 각도 구동 범위를 가지고 있고 많은 수의 멤버를 연결할 수 있다. 마스터 멤버 엔드는 노드 부의 내장된 구형 매니퓰레이터로, 토폴로지 재구성 시 멤버를 이동시키는데 사용된다. VTT는 기하학적 형상을 변화하여 구르는 움직임을 통해 주행한다. VTT의 주행 알고리즘은 서포트 폴리곤 계획 단계, 무게 중심 계획 단계, 노드 위치 계획 단계로 이루어진다. 서포트 폴리곤 계획 단계에서는 새롭게 제안된 무작위 탐색 (random search) 알고리즘인 Polygon-Based Random Tree (PRT)을 적용해 서포트 폴리곤의 경로를 계획한다. 무게 중심 계획 단계에서는 안정성을 최대화하는 VTT의 무게 중심 궤적을 계획한다. 계획된 서포트 폴리곤 경로와 무게 중심 궤적을 VTT가 제한 조건으로부터 먼 좋은 상태의 형상을 유지하게 하여 복잡한 환경에 대해서도 경로 계획이 실패하지 않고 안정적으로 이루어질 수 있도록 한다. 노드 위치 계획 단계에서는 서포트 폴리곤 경로와 노드 위치의 궤적을 추종하는 노드 위치 궤적을 계획한다. 이 과정에서 비충격 롤링 이동 알고리즘 (Non-Impact Rolling locomotion algorithm)을 적용하여 지면과의 충돌로 인한 충격이 일어나지 않는 궤적을 계획한다. 실제 VTT의 제한 조건을 반영한 모델에 본 알고리즘을 적용하여 시뮬레이션을 수행한 결과, VTT가 모든 제한 조건을 만족하고 장애물을 회피하면서 목표 지점에 도달할 수 있음을 확인하였다.Chapter 1. Introduction 1 1.1 Motivation 1 1.2 Previous Truss Type Modular Robot 4 1.3 Previous Research on VTTs Locomotion 8 1.3.1 Heuristic Based Methods 9 1.3.2 Optimization Based Method 10 1.4 Objectives of Locomotion Algorithm 12 1.5 Contribution of Thesis 13 1.5.1 Introduction to Hardware Design of VTT 13 1.5.2 Stable Rolling Locomotion of VTT 15 Chapter 2. Design of Variable Topology Truss 17 2.1 Member Design 18 2.1.1 Spiral Zipper 20 2.1.2 Tensioner 26 2.2 Node Design 28 2.2.1 Passive Member-End and Sphere 29 2.2.2 Master Member-End 36 2.3 Control System 40 2.4 Node Position Control Experiment 44 Chapter 3. Mathematical Model of Variable Topology Truss 47 3.1 Configuration and Terminology 47 3.2 Inverse Kinematics 50 3.3 Constraints 51 3.4 Stability Criteria 64 Chapter 4. Locomotion Algorithm 66 4.1 Concept of Locomotion Algorithm 67 4.1.1 Method for Successful Planning and Obstacle Avoidance 67 4.1.2 Method to Prevent Damage from the Ground 71 4.1.3 Step of Locomotion Algorithm 72 4.2 Support Polygon Planning 73 4.2.1 Polygon-Based Random Tree (PRT) Algorithm 73 4.2.2 Probabilistic Completeness of PRT Algorithm 79 4.3 Center of Mass Planning 85 4.4 Node Position Planning 86 4.4.1 Concept of Non-Impact Rolling Locomotion 86 4.4.2 Planning Algorithm for Non-Impact Rolling Locomotion 89 4.4.3 Optimization Problem of Moving Phase 94 4.4.4 Optimization Problem of Landing Phase 98 4.4.5 Optimization Problem of Transient Phase 99 Chapter 5. Experimental Verification 100 5.1 Case Study 1: Actual VTT Prototype 101 5.1.1 Simulation Condition 101 5.1.2 Obstacle Avoidance Method 103 5.1.3 Simulation Result 104 5.2 Case Study 2: Environment with Narrow Passage 111 5.2.1 Simulation Condition 111 5.2.2 Support Polygon Planning with Varying Nominal Length 114 5.2.3 Simulation Result 117 Chapter 6. Conclusion 126 Bibliography 129 Abstract in Korean 134Docto