Utilizing Compliance To Address Modern Challenges in Robotics

Mechanical compliance will be an essential component for agile robots as they begin to leave the laboratory settings and join our world. The most crucial finding of this dissertation is showing how lessons learned from soft robotics can be adapted into traditional robotics to introduce compliance. Therefore, it presents practical knowledge on how to build soft bodied sensor and actuation modules: first example being soft-bodied curvature sensors. These sensors contain both standard electronic components soldered on flexible PCBs and hyperelastic materials that cover the electronics. They are built by curing multi-material composites inside hyper elastic materials. Then it shows, via precise sensing by using magnets and Hall-effect sensors, how closed-loop control of soft actuation modules can be achieved via proprioceptive feedback. Once curvature sensing idea is verified, the dissertation describes how the same sensing methodology, along with the same multi-material manufacturing technique can be utilized to construct soft bodied tri-axial force sensors. It shows experimentally that these sensors can be used by traditional robotic grippers to increase grasping quality. At this point, I observe that compliance is an important property that robots may utilize for different types of motions. One example being Raibert\u27s 2D hopper mechanism. It uses its leg-spring to store energy while on the ground and release this energy before jumping. I observe that via soft material design, it would be possible to embed compliance directly into the linkage design itself. So I go over the design details of an extremely lightweight compliant five-bar mechanism design that can store energy when compressed via soft ligaments embedded in its joints. I experimentally show that the compliant leg design offers increased efficiency compared to a rigid counterpart. I also utilize the previously mentioned soft bodied force sensors for rapid contact detection (~5-10 Hz) in the hopper test platform. In the end, this thesis connects soft robotics with the traditional body of robotic knowledge in two aspects: a) I show that manufacturing techniques we use for soft bodied sensor/actuator designs can be utilized for creating soft ligaments that add strength and compliance to robot joints; and b) I demonstrate that soft bodied force sensing techniques can be used reliably for robotic contact detection

Technology for large space systems: A special bibliography with indexes

This bibliography lists 460 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1968 and December 31, 1978. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design in the area of the Large Space Systems Technology (LSST) Program. Subject matter is grouped according to systems, interactive analysis and design, structural concepts, control systems, electronics, advanced materials, assembly concepts, propulsion, and flight experiments

Algorithmic Modelling of Folded Surfaces. Analysis and Design of Folded Surfaces in Architecture and Manufacturing.

Both in the field of design and architecture origami is often taken as a reference for its kinetic proprieties and its elegant appearance. Dynamic facades, fast deployment structures, temporary shelters, portable furniture, retractile roofs, are some examples which can take advantage of the kinetic properties of the origami. While designing with origami, the designer needs to control shape and motion at the same time, which increases the complexity of the design process. This complexity of the design process may lead the designers to choose a solution where the patterns are mere copies of well-known patterns or to reference to the origami only for ornamental purposes. The origami-inspired projects that we gathered and studied in the fields of architecture, manufacturing and fashion, confirmed this trend. We observed that the cause of this lack of variety could also be attributed to insufficient knowledge, or to inefficiency of the design tools. Many researchers studied the mathematical implications of origami, to be able to design specific patterns for precise applications. However, this theoretical knowledge is hard to apply directly to different practical projects without a deep understanding of these theorems. Thus, in this thesis, we aim to narrow the gap between potentialities of this discipline and limits of the available designing tools, by proposing a simplified synthetic constructive approach, applied with a parametric modeller, which allows the designers to bypass scripting and algebraic formulations and, at the same time, it increases the design freedom. Among the cases studies, we propose some fabrication-aimed examples, which introduce the subjects of thick-origami, distribution of stresses and analysis of deformations of the folded models.Nei campi dell’architettura e dell’industrial design, l’origami è spesso preso come riferimento per le sue proprietà cinetiche e le sue forme eleganti. Facciate dinamiche, strutture pieghevoli, rifugi temporanei, arredi portatili, tetti retrattili, sono alcuni esempi di progetti che potrebbero beneficiare delle proprietà cinetiche dell’origami. Progettare con l’origami richiede di controllare forma e movimento contemporaneamente; ciò aumenta la complessità del processo progettuale. Questa difficoltà progettuale può portare i progettisti a scegliere soluzioni che non sono altro che mere copie di pattern noti o a considerare l’origami come riferimento solo per ragioni ornamentali. I progetti ispirati all’origami che abbiamo raccolto ed analizzato nei campi di architettura, industria manifatturiera, e moda, confermano questo trend. Abbiamo osservato che la causa di questo mero utilizzo potrebbe essere attribuibile a preparazione insufficiente del progettista o a inefficienza degli strumenti progettuali. Diversi ricercatori hanno studiato le implicazioni matematiche dell’origami, per poter progettare specifici pattern per precise applicazioni. Nonostante ciò, questa conoscenza teorica è difficile da applicare direttamente ad altri progetti pratici senza una profonda comprensione di questi teoremi. Questa tesi punta quindi a ridurre il divario tra potenzialità di questa disciplina e limiti imposti dagli strumenti progettuali disponibili, proponendo un approccio sintetico e costruttivo semplificato, che permetta ai progettisti di evitare scripting e formulazioni algebriche, aumentando allo stesso tempo la libertà progettuale. Tra i casi studio, proponiamo anche alcuni esempi mirati alla fabbricazione che introducono il tema dell’origami a spessore non nullo, della distribuzione delle forze e dell’analisi delle deformazioni sui modelli piegati

The 24th Aerospace Mechanisms Symposium

The proceedings of the symposium are reported. Technological areas covered include actuators, aerospace mechanism applications for ground support equipment, lubricants, latches, connectors, and other mechanisms for large space structures

Haptics: Science, Technology, Applications

This open access book constitutes the proceedings of the 13th International Conference on Human Haptic Sensing and Touch Enabled Computer Applications, EuroHaptics 2022, held in Hamburg, Germany, in May 2022. The 36 regular papers included in this book were carefully reviewed and selected from 129 submissions. They were organized in topical sections as follows: haptic science; haptic technology; and haptic applications

Design & modelling of a composite rudderless aeroelastic fin structure

This thesis presents the study of a gapless and rudderless aeroelastic fin (GRAF) to enhance the directional stability and controllability of an aircraft. The GRAF concept was proposed and developed in the wake of previous research, targeted to improve flight performance and manoeuvrability, and to reduce fuel consumption and airframe weight. The study involved the subjects of aerodynamics, structural design and analysis, and flight mechanics. The work includes conceptual design, structural modelling, aeroelastic analysis and flight performance evaluation of a GRAF variant designed for a small subsonic Unmanned Aerial Vehicle (UAV). The Eclipse UAV, a platform designed by part time students at the Department of Aerospace Engineering of Cranfield University, was chosen as a case study. A new approach to design a more effective fin with an unconventional structural layout and novel techniques which have not been investigated in previous research is proposed. Despite the GRAF planform being similar to classical fin-hinged rudder configurations, it is provided with a flexible gapless control surface, kept as one continuous piece and integrated with the fin primary structure. With its fixed root and rudderless feature, the GRAF adopts an original method of operation. Its way of working relies upon an unconventional technique of combining morphing technology and aeroelastic effect. The morphable configuration is twisted to gain an aeroelastically beneficial effect to enhance the efficiency and manoeuvrability of the aircraft. This warping capability of the fin is the key role player enabling the GRAF surface to seamlessly generate the required aerodynamic forces. Unlike the conventional structures designed to be as rigid as possible to withstand the external loads, the GRAF will exploit its structure‟s flexibility to use the aeroelastically induced twist deformations for a self-adaptive warping behaviour and improve flight dynamic response and performance. In order to ensure the above features are achievable in practice, further study on the structural configuration was conducted. To achieve performance improvement, together with the original structural layout and aeroelastic effect exploitation, another three novel key components are investigated, proposed and introduced in the GRAF model. A structurally integrated actuation system, termed L-shape stringers device (LSS), is designed to transform actuator axial forces in spanwise distributed bending moments, to create seamless deformations of the trailing edge (TE) section. An innovative trailing edge joint, namely the swivel edge closure, is specifically designed to enhance the mobility and degrees of freedom of the trailing edge box. It is a revolutionary concept which, by virtually interrupting the structural integrity of the closed TE section, allows relative translation and rotation of the TE panels. Finally, it is the novel concept of the slot-connection that, whilst appearing to clamp the GRAF structure inside the slot, actually enables the design to increase the twist angle at the tip of the fin without overstressing the materials. In order to enhance the GRAF efficiency, a tailored design of the fin structure was conducted. A novel internal structure configuration integrated with the key components has been designed to be connected to a flexible cladding skin, rotating ribs and a load-carrying tubular beam all of which constitute the primary parts of the GRAF model. With the ultimate goal of a lighter tail version, the entire design has been made by using composite, light frames, in an engineering trade-off of stiffness, elasticity, weight and cost of both glass and carbon fibre laminates. The analysis via 2-D aerodynamic codes and FEA was conducted to assess and validate the GRAF model and the obtained performance. Static linear elastic analysis has been carried out to verify the structural layout of the novel design subject to strength and stiffness criteria in addition to the fin warping and cambering capabilities. Also an investigation of aeroelastic stability related to steady and unsteady aerodynamic conditions has been carried out during the model analysis phase. The study has shown that although the GRAF divergence and flutter margins are slightly smaller than those of the conventional fin, the design and performance requirements are satisfied within the very challenging objective of a lighter vertical tail structure.The dynamic analysis study has also demonstrated the beneficial effect obtained by damping yawing oscillations when such a self-adaptive structure, compared to a rigid one, can be operated under cross wind circumstances. The manufacturing feasibility and assembly of the GRAF structure has been explored with the construction of a 1:1 scale model of the fin prototype. The model has been used as concept demonstrator to assess the functionality of the introduced technical novelties, the ease of manufacturing and the structural weight of the final assembly.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

A Numerical Exploration of the Crystalline Lens: from Presbyopia to Cataracts and Intraocular Lenses

Esta tesis aborda, de forma numérica, la resolución de tres problemas relacionados con el cristalino. En primer lugar, se ha construido un modelo de elementos finitos del cristalino humano para abordar la simulación de la acomodación, gracias a la incorporación de la contracción muscular del músculo ciliar. El modelo se ha validado con resultados experimentales comparando con Ramasubramanian & Glasser, 2015. Con el mismo modelo, se ha estudiado como afecta el cambio de las propiedades mecánicas de los tejidos del cristalino en la pérdida de amplitud de la acomodación con la edad para entender si la rigidización de los tejidos juega un papel importante en la presbicia. La conclusión principal del estudio numérico ha sido que las propiedades mecánicas y tensiones iniciales de la cápsula del cristalino proporciona la fuerza necesaria para acomodar, es decir, cambiar su curvatura para enfocar de cerca. Especificamente, el ratio de rígidez entre el núcleo y el cristalino gobierna cómo el cristalino cambia de forma. Con la edad, se produce una rigidización del núcleo, y el incremento de la relación entre ambas rigideces (núcleo y corteza) podría ser el principal responsable de la pérdida de la amplitud de acomodación con la edad. En segundo lugar, se ha estudiado la estabilidad biomecánica de diferentes diseños de lentes intraoculares (IOL). Las IOLs sustituyen las funciones del cristalino en pacientes con cataratas, es por ello necesario garantizar su estabilidad en el interior del saco para garantizar una visión adecuada. Entre los aspectos estudiados destaca la caracterización mecánica de los materiales acrílicos con los que se fabrican las lentes. Para ello, se han combinado ensayos uniaxiales con ensayos de indentación. Éstos últimos se han utilizado para caracterizar la respuesta visco-elástica del material. El definir la respuesta del material mediante modelos visco hiperelásticos es necesario para posteriormente analizar la estabilidad de la IOL mediante elementos finitos. Este análisis se ha defino a dos niveles, en un primer nivel se analiza la estabilidad de la IOL simulando el ensayo establecido en la norma ISO 11979-3:2012. Esta norma es de obligado cumplimiento para los fabricantes antes de introducir un nuevo diseño en el mercado. Se ha realizado un estudio estadístico para estudiar el efecto de la geometría de los hápticos tipo C-loop en la estabilidad mecánica de la IOL, obteniendo que el entronque, la unión entre el háptico y la lente, es el parámetro más influyente. Para validar la metodología numérica, se fabricaron varios diseños y se analizaron experimentalmente para comparar los resultados correspondientes con biomarcadores mecánicos (desplazamiento axial, rotación y la inclinación de la IOL) que están relacionados con la calidad visual resultante de la IOL. En un segundo nivel, se ha simulado la respuesta de la IOL en el interior del saco capsular, estudiando la influencia de diferentes parámetros del paciente, como geometría y propiedades mecánicas del saco. También se ha analizado la influencia de parámetros de la cirugía de la catarata, como es el diámetro y posición de la capsulorexis. En este último nivel, se ha estudiado tanto la respuesta instantánea, es decir, tras la cirugía, como a largo plazo, cuando sucede la huella de fusión (fusion footprint) entre la cápsula y la IOL. Para que los modelos computacionales sean de ayuda a los cirujanos o puedan servir en tiempo real, se ha planteado una metodología basada en inteligencia artificial. En este caso la base de datos de partida corresponde a modelos numéricos altamente fiables y con ellos, se genera datos con los que se entrena la red neuronal. En esta tesis, se estudia la estabilidad de la IOL en función del diámetro de compresión del paciente y la edad, que a su vez influye en las propiedades mecánicas del saco. Por último, se ha evaluado experimentalmente la influencia del material de la IOL (hidrófobo o hidrofílico) y su geometría durante la inyección de la IOL en el saco, registrando la fuerza de inyección que debe realizar el cirujano. De cara a evitar complicaciones (se dañe la IOL o el tejido corneal) durante la cirugía, es conveniente que la fuerza a ejercer sea baja. Se ha comprobado que su valor está fuertemente influenciado por el material de la lente.¿Por qué el cristalino es de vital importancia?El cristalino es el responsable tanto del cambio dinámico de la potencia refractiva del ojo a través del mecanismo de acomodación como de la corrección de las aberraciones de la córnea. El cambio óptico dinámico es consecuencia de un cambio geométrico del cristalino. Sin embargo, a medida que el cristalino envejece, disminuye este cambio óptico dinámico y se opacifica, lo que da lugar a las dos patologías comúnmente asociadas al envejecimiento como es, la presbicia y las cataratas. Por este motivo, en esta tesis doctoral se ha profundizado en el estudio mecánico del cristalino y tras su sustitución mediante una lente intraocular artificial durante la cirugía de catarata. La metodología establecida pueden ayudar en un futuro tanto al diseño de nuevos implantes como a los oftalmólogos a seleccionar la IOL adecuada a cada paciente para mejora su calidad visual.This thesis addresses three different case studies related to the crystalline lens. Firstly, the mechanical causes of the loss of accommodation amplitude with age, called presbyopia, were analysed through the finite element method. A high-fidelity simulation of the mechanism of accommodation including the contraction of the ciliary muscle was developed. This allowed us to analyse accommodation in depth, showing that although the lens capsule provides the force to accommodate, the stiffness ratio between the lens cortex and lens nucleus could have a higher effect on how the lens changes its shape. Secondly, the biomechanical stability of intraocular lenses (IOLs) was analysed. IOLs are essential for post-cataract patients as they substitute the functions of the crystalline lens. In this thesis, a wide variety of solutions were addressed: from the visco- and hyper-elasticity characterisation of IOL acrylic materials from depth sensing indentation and uniaxial tests to the simulation of the IOL biomechanical stability inside the capsular bag. We also performed a high-fidelity simulation of the IOL compression standards tests required by the IOLs to be commercialised and the results obtained were compared with clinical data. Lastly, we developed a patient-specific methodology to customise the IOL haptic design. Most of the numerical methology developed is intended to be used in the IOL pre-design phase to avoid costs and time. Thirdly, the IOL delivery during cataract surgery according to haptic and material design and injector characteristics was experimentally studied to avoid any possibility of IOL and eye damage. Apart from the injector size, the IOL material was the most influential parameter in the force exerted in IOL delivery. Why is the crystalline lens of vital importance? The crystalline lens is the responsible for both the dynamic change of the refractive power of the eye through the mechanism of accommodation and the correction of cornea aberrations. The dynamic optical change is consequence of change of the lens shape. However, as the lens ages over time, it decreases this dynamic optical change and becomes cloudy, what leads to the two most common lens-related pathologies, presbyopia and cataracts. Therefore, it is of utmost importance to study the lens mechanics and all issues related to the artificial intraocular lens that substitutes the lens during cataract surgery.<br /