Towards an ontology for soft robots: What is soft?

The advent of soft robotics represents a profound change in the forms robots will take in the future. However, this revolutionary change has already yielded such a diverse collection of robots that attempts at defining this group do not reflect many existing ‘soft’ robots. This paper aims to address this issue by scrutinising a number of descriptions of soft robots arising from a literature review with the intention of determining a coherent meaning for soft. We also present a classification of existing soft robots to initiate the development of a soft robotic ontology. Finally, discrepancies in prescribed ranges of Young’s modulus, a frequently used criterion for the selection of soft materials, are explained and discussed. A detailed visual comparison of these ranges and supporting data is also presented

Developing Design and Analysis Framework for Hybrid Mechanical-Digital Control of Soft Robots: from Mechanics-Based Motion Sequencing to Physical Reservoir Computing

The recent advances in the field of soft robotics have made autonomous soft robots working in unstructured dynamic environments a close reality. These soft robots can potentially collaborate with humans without causing any harm, they can handle fragile objects safely, perform delicate surgeries inside body, etc. In our research we focus on origami based compliant mechanisms, that can be used as soft robotic skeleton. Origami mechanisms are inherently compliant, lightweight, compact, and possess unique mechanical properties such as– multi-stability, nonlinear dynamics, etc. Researchers have shown that multi-stable mechanisms have applications in motion-sequencing applications. Additionally, the nonlinear dynamic properties of origami and other soft, compliant mechanisms are shown to be useful for ‘morphological computation’ in which the body of the robot itself takes part in performing complex computations required for its control. In our research we demonstrate the motion-sequencing capability of multi-stable mechanisms through the example of bistable Kresling origami robot that is capable of peristaltic locomotion. Through careful theoretical analysis and thorough experiments, we show that we can harness multistability embedded in the origami robotic skeleton for generating actuation cycle of a peristaltic-like locomotion gait. The salient feature of this compliant robot is that we need only a single linear actuator to control the total length of the robot, and the snap-through actions generated during this motion autonomously change the individual segment lengths that lead to earthworm-like peristaltic locomotion gait. In effect, the motion-sequencing is hard-coded or embedded in the origami robot skeleton. This approach is expected to reduce the control requirement drastically as the robotic skeleton itself takes part in performing low-level control tasks. The soft robots that work in dynamic environments should be able to sense their surrounding and adapt their behavior autonomously to perform given tasks successfully. Thus, hard-coding a certain behavior as in motion-sequencing is not a viable option anymore. This led us to explore Physical Reservoir Computing (PRC), a computational framework that uses a physical body with nonlinear properties as a ‘dynamic reservoir’ for performing complex computations. The compliant robot ‘trained’ using this framework should be able to sense its surroundings and respond to them autonomously via an extensive network of sensor-actuator network embedded in robotic skeleton. We show for the first time through extensive numerical analysis that origami mechanisms can work as physical reservoirs. We also successfully demonstrate the emulation task using a Miura-ori based reservoir. The results of this work will pave the way for intelligently designed origami-based robots with embodied intelligence. These next generation of soft robots will be able to coordinate and modulate their activities autonomously such as switching locomotion gait and resisting external disturbances while navigating through unstructured environments

Super Ball Bot - Structures for Planetary Landing and Exploration

Small, light-weight and low-cost missions will become increasingly important to NASA's exploration goals for our solar system. Ideally teams of dozens or even hundreds of small, collapsable robots, weighing only a few kilograms a piece, will be conveniently packed during launch and would reliably separate and unpack at their destination. Such teams will allow rapid, reliable in-situ exploration of hazardous destination such as Titan, where imprecise terrain knowledge and unstable precipitation cycles make single-robot exploration problematic. Unfortunately landing many lightweight conventional robots is difficult with conventional technology. Current robot designs are delicate, requiring combinations of devices such as parachutes, retrorockets and impact balloons to minimize impact forces and to place a robot in a proper orientation. Instead we propose to develop a radically different robot based on a "tensegrity" built purely upon tensile and compression elements. These robots can be light-weight, absorb strong impacts, are redundant against single-point failures, can recover from different landing orientations and are easy to collapse and uncollapse. We believe tensegrity robot technology can play a critical role in future planetary exploration

Super Ball Bot - Structures for Planetary Landing and Exploration, NIAC Phase 2 Final Report

Small, light-weight and low-cost missions will become increasingly important to NASA's exploration goals. Ideally teams of small, collapsible, light weight robots, will be conveniently packed during launch and would reliably separate and unpack at their destination. Such robots will allow rapid, reliable in-situ exploration of hazardous destination such as Titan, where imprecise terrain knowledge and unstable precipitation cycles make single-robot exploration problematic. Unfortunately landing lightweight conventional robots is difficult with current technology. Current robot designs are delicate, requiring a complex combination of devices such as parachutes, retrorockets and impact balloons to minimize impact forces and to place a robot in a proper orientation. Instead we are developing a radically different robot based on a "tensegrity" structure and built purely with tensile and compression elements. Such robots can be both a landing and a mobility platform allowing for dramatically simpler mission profile and reduced costs. These multi-purpose robots can be light-weight, compactly stored and deployed, absorb strong impacts, are redundant against single-point failures, can recover from different landing orientations and can provide surface mobility. These properties allow for unique mission profiles that can be carried out with low cost and high reliability and which minimizes the inefficient dependance on "use once and discard" mass associated with traditional landing systems. We believe tensegrity robot technology can play a critical role in future planetary exploration

Adaptive Multi-Functional Space Systems for Micro-Climate Control

This report summarizes the work done during the Adaptive Multifunctional Systems for Microclimate Control Study held at the Caltech Keck Institute for Space Studies (KISS) in 2014-2015. Dr. Marco Quadrelli (JPL), Dr. James Lyke (AFRL), and Prof. Sergio Pellegrino (Caltech) led the Study, which included two workshops: the first in May of 2014, and another in February of 2015. The Final Report of the Study presented here describes the potential relevance of adaptive multifunctional systems for microclimate control to the missions outlined in the 2010 NRC Decadal Survey. The objective of the Study was to adapt the most recent advances in multifunctional reconfigurable and adaptive structures to enable a microenvironment control to support space exploration in extreme environments (EE). The technical goal was to identify the most efficient materials, architectures, structures and means of deployment/reconfiguration, system autonomy and energy management solutions needed to optimally project/generate a micro-environment around space assets. For example, compact packed thin-layer reflective structures unfolding to large areas can reflect solar energy, warming and illuminating assets such as exploration rovers on Mars or human habitats on the Moon. This novel solution is called an energy-projecting multifunctional system (EPMFS), which are composed of Multifunctional Systems (MFS) and Energy-Projecting Systems (EPS)

Análise estática, dinâmica e modal de estruturas e mecanismos tensegrity

Orientador: Paulo Roberto Gardel KurkaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia MecânicaResumo: O desenvolvimento de estruturas mais leves, finas, rígidas ou inteligentes é um desafio constante entre engenheiros e cientistas de qualquer área. Sistemas tensegrity, que são formados por corpos rígidos em compressão e cabos em tração, têm perspectiva de serem amplamente aplicados pelas indústrias espacial, civil, mecânica, aeronáutica ou biomédica. O projetista de um tensegrity pode controlar sua rigidez e formato através da mudança de tensão nos cabos, cujos comportamentos são explorados neste trabalho via protótipos e simulações. Um modelo foi sugerido para otimizar massa e volume de uma antena de satélite, o mecanismo tensegrity foi criado para ser lançado num formato colapsado, economizando volume dentro do foguete, e expandido no espaço através da contração de determinados cabos. Em seguida, as tensões dos cabos de um prisma tensegrity foram variadas e a mudança na rigidez foi avaliada por análise modal. Por fim, uma torre tensegrity bidimensional foi submetida a grandes deformações, sua análise estática não linear foi implementada e as frequências naturais das posições deformadas foram calculadas. As três metodologias foram implementadas e, posteriormente, validadas em três experimentos distintos, estes ressaltando os efeitos de cada propriedade em avaliação. O objetivo deste trabalho é propor um procedimento para desenvolver o projeto e construção de uma estrutura tensegrity que englobe as três metodologias: definindo sua expansão a partir de uma configuração colapsada, o controle da rigidez quando estável e a nova posição caso algum esforço provoque grandes deformações. Portanto, além do objetivo prático do primeiro tópico, este trabalho tem como meta fornecer uma documentação geral de soluções relacionadas a estruturas e mecanismos tensegrityAbstract: The development of lighter, thinner, stiffer or smarter structures is a constant challenge among engineers and scientists of all fields. Tensegrity systems, which are formed by rigid bodies under compression and cables under traction, are likely to be largely used by the space, civil, mechanical, aeronautical and biomedical industries. The designer of a tensegrity can control its stiffness and shape by changing the tension in the cables, these behaviours are explored in this work via prototypes and simulations. A model was suggested to optimize mass and volume of a satellite antenna, a tensegrity mechanism was created to be launched in a reduced shape, saving volume in the launcher, and expanded in space by pulling specific tendons. Secondly, the tensions of a tensegrity prism's cables were varied and the change in stiffness was assessed through modal analysis. Finally, a 2D tensegrity tower was put under large deformations, its nonlinear static analysis was implemented and the natural frequencies of the deformed configurations were calculated. All the three methodologies have been implemented and, later, validated through experiments designed to highlight each property of concern. The objective of this work is to propose procedures to develop and build a tensegrity structure that carry those three methodologies: defining its expansion from a compact configuration, its stiffness control once the expansion is finished and its new shape if any load generates large displacements. Thus, beyond the practical end of the first topic, the goal of this work is to provide a general document of solutions related to tensegrity structures and mechanismsMestradoMecanica dos Sólidos e Projeto MecanicoMestre em Engenharia Mecânica132166/2018-6CNP

Soft Scalable Self-Reconfigurable Modular Cellbot

Hazardous environments such as disaster affected areas, outer space, and radiation affected areas are dangerous for humans. Autonomous systems which can navigate through these environments would reduce risk of life. The terrains in these applications are diverse and unknown, hence there is a requirement for a robot which can self-adapt its morphology and use suitable control to optimally move in the desired manner. Although there exist monolithic robots for some of these applications, such as the Curiosity rover for Mars exploration, a modular robot containing multiple simple units could increase the fault tolerance. A modular design also enables scaling up or down of the robot based on the current task, for example, scaling up by connecting multiple units to cover a wider area or scaling down to pass through a tight space.Taking bio-inspiration from cells, where – based on environmental conditions – cells come together to form different structures to carry out different tasks, a soft modular robot called Cellbot was developed which was composed of multiple units called ‘cells’. Tests were conducted to understand the cellbot movement over different frictional surfaces for different actuation functions, the number of cells connected in a line (1D), and the shapes formed by connecting cells in 2D. A simulation model was developed to test a large range of frictional values and actuation functions for different friction coefficients. Based on the obtained results, cells could be designed using a material with frictional properties lying in the optimal locomotion range. In other cases, where the application has diverse terrains, the number of connected units can be changed to optimise the robot locomotion. Initial tests were conducted using a ‘ball robot’, where the cellbot was designed using balls which touch ground to exploit friction and actuators to provide force to move the robot. The model was extended to develop, a ‘bellow robot’ which was fabricated using hyper-elastic bellows and employed pneumatic actuation. The amount of inflation of a cell and its neighbouring cells determined if the cell would touch the ground or be lifted up. This was used to change cell behaviour where a cell could be touching ground to provide anchoring friction, or lifted to push or pull the cells and thereby move the robot. The cells were connected by magnets which could be disconnected and reconnected by morphing the robot body. The cellbot can thus reconfigure by changing the number of connected units or its shape. The easy detachment can be used to remove and replace damaged cells. Complex cellbot movements can be achieved by either switching between different robot morphologies or by changing actuation control.Future cellbots will be controlled remotely to change their morphology, control, and number of connected cells, making them suitable for missions which require fault tolerance and autonomous shape adaptation. The proposed cellbot platform has the potential to reduce the energy, time and costs in comparison to traditional robots and has potential for applications such as exploration missions for outer space, search and rescue missions for disaster affected areas, internal medical procedures, and nuclear decommissioning.<br/