Development of assembly and joint concepts for erectable space structures

The technology associated with the on-orbit assembly of tetrahedral truss platforms erected of graphite epoxy tapered columns is examined. Associated with the assembly process is the design and fabrication of nine member node joints. Two such joints demonstrating somewhat different technology were designed and fabricated. Two methods of automatic assembly using the node designs were investigated, and the time of assembly of tetrahedral truss structures up to 1 square km in size was estimated. The effect of column and node joint packaging on the Space Shuttle cargo bay is examined. A brief discussion is included of operating cost considerations and the selection of energy sources. Consideration was given to the design assembly machines from 5 m to 20 m. The smaller machines, mounted on the Space Shuttle, are deployable and restowable. They provide a means of demonstrating the capabilities of the concept and of erecting small specialized platforms on relatively short notice

Design and Control of the "TransBoat": A Transformable Unmanned Surface Vehicle for Overwater Construction

This paper presents the TransBoat, a novel omnidirectional unmanned surface vehicle (USV) with a magnetbased docking system for overwater construction with wave disturbances. This is the first such USV that can build overwater structures by transporting modules. The TransBoat incorporates two features designed to reject wave disturbances. First, the TransBoat's expandable body structure can actively transform from a mono-hull into a multi-hull for stabilization in turbulent environments by extending its four outrigger hulls. Second, a real-time nonlinear model predictive control (NMPC) scheme is proposed for all shapes of the TransBoat to enhance its maneuverability and resist disturbance to its movement, based on a nonlinear dynamic model. An experimental approach is proposed to identify the parameters of the dynamic model, and a subsequent trajectory tracking test validates the dynamics, NMPC controller and system mobility. Further, docking experiments identify improved performance in the expanded form of the TransBoat compared with the contracted form, including an increased success rate (of ~ 10%) and reduced docking time (of ~ 40 s on average). Finally, a bridge construction test verifies our system design and the NMPC control method

Adaptive and reconfigurable robotic gripper hands with a meso-scale gripping range

Grippers and robotic hands are essential and important end-effectors of robotic manipulators. Developing a gripper hand that can grasp a large variety of objects precisely and stably is still an aspiration even though research in this area has been carried out for several decades. This thesis provides a development approach and a series of gripper hands which can bridge the gap between micro-gripper and macro-gripper by extending the gripping range to the mesoscopic scale (meso-scale). Reconfigurable topology and variable mobility of the design offer versatility and adaptability for the changing environment and demands. By investigating human grasping behaviours and the unique structures of human hand, a CFB-based finger joint for anthropomorphic finger is developed to mimic a human finger with a large grasping range. The centrodes of CFB mechanism are explored and a contact-aided CFB mechanism is developed to increase stiffness of finger joints. An integrated gripper structure comprising cross four-bar (CFB) and remote-centre-of-motion (RCM) mechanisms is developed to mimic key functionalities of human hand. Kinematics and kinetostatic analyses of the CFB mechanism for multimode gripping are conducted to achieve passive-adjusting motion. A novel RCM-based finger with angular, parallel and underactuated motion is invented. Kinematics and stable gripping analyses of the RCM-based multi-motion finger are also investigated. The integrated design with CFB and RCM mechanisms provides a novel concept of a multi-mode gripper that aims to tackle the challenge of changing over for various sizes of objects gripping in mesoscopic scale range. Based on the novel designed mechanisms and design philosophy, a class of gripper hands in terms of adaptive meso-grippers, power-precision grippers and reconfigurable hands are developed. The novel features of the gripper hands are one degree of freedom (DoF), self-adaptive, reconfigurable and multi-mode. Prototypes are manufactured by 3D printing and the grasping abilities are tested to verify the design approach.EPSR

Transformable and transportable architecture: analysis of buildings components and strategies for project design

The present Master Thesis is a research about different aspects of transformable transportable buildings, like components as mechanisms for movement, building design strategies and construction detailing, aimed a better understanding of the design and technical necessities of this particular type of architecture. The first application for transformable and transportable buildings were developed during post-war period in an urge for solving housing problems and the transformation of the industries, highly influenced by the development of spatial structures. And until few years ago, the design of this type of buildings was only focused on temporary structures or few applications to real building solutions being pure concepts of futuristic image but with the lack of technical development. Recently, a new type of transportable and transformable architecture is being produced as solutions for every-day-live use, and accepted in the community they are inserted. In this type of projects the investigation is going to be focused, analyzing from building components and connections to technical design.La presente Tesis de Máster es una investigación que trata sobre diferentes aspectos de edificios transformables y transportables, tales como componentes como mecanismos para generar movimiento, estrategias de diseño y detalles constructivos, enfocada en mejorar la comprensión de las necesidad técnico-constructivas de este tipo particular de arquitectura. Las primeras aplicaciones de edificios transformables y transportables fueron desarrolladas durante el período de posguerra como resultado de la necesidad de solucionar problemas habitacionales y la transformación de las industrias, altamente influenciados por los avances de las estructuras espaciales. Y hasta pocos años, el diseño de este tipo de edificios era sólo enfocado en estructuras temporales o pocas aplicaciones a soluciones reales, siendo la mayoría puros conceptos con una imagen futurística pero con deficiencias en su desarrollo técnico. Recientemente, un nuevo tipo de arquitectura transportable y transformable está siendo producida, como soluciones para el uso diario y aceptado por las comunidades donde son insertados. En este tipo de proyectos se concentrará la investigación, analizando desde los componentes y conexiones de los edificios hacia los aspectos técnicos del diseño

Kinky structures

Rotational springs are not widely used in structural engineering other than within undergraduate texts to aid with the understanding of strut buckling or other similar theoretical exercises.The inclusion of rotational springs can significantly alter the behaviour of a structure, bringing several potential benefits if inserted strategically. For instance, allowing a frame to be delivered to site as a single deployable piece, where the rotational springs introduce an element of temporary stability during erection; by ensuring hinges form in specific locations during extreme loading events, creating reliable load paths whilst retaining structural integrity; or by limiting the axial force in specific elements, forcing an element to buckle at specific loads. Currently, there is a significant gap in the existing research with regards the analysis and behaviour of structures that have springs distributed through the frame. The inclusion of springs within structural frames will typically encourage gross, yet controlled and predictable displacements that are challenging to analyse. Equally, deployable structures require an element of instability to deploy. With most research focusing on the packed and deployed states of these structures, there is still considerable research to be done on the structural performance of the intermediate stages of deployment. Several forms of deployable structure, such as cable-chain arches for example, are vulnerable and unstable during their intermediate deployment phase and it is proposed that the integration of rotational springs in these types of structure could help control the deployment and maintain stability from a packed shape into the final in-service form as well as preventing phenomenon such as snap-through buckling under large loads. Original work within this thesis creates several repeatable and reliable methods for undertaking buckling analysis of sprung chains to determine an initial balanced equilibrium form to which in-service loadings can then be applied as well as determining the post-buckled behaviour for sprung structures. The application of numerical analysis methods is demonstrated as giving reliable results for single and multiple degrees of freedom systems, but due to the potential for incompatibilities between the stiffnesses of the rotational springs and beam elements there are issues associated with ill-conditioning and methods have been established to identify and mitigate these effects.Alternative structural forms, beyond simple arches, have also been developed through seeking inspiration from the higher buckling modes. Shapes resembling these higher modes have been generated through the careful manipulation of spring stiffnesses (mobilising linear and non-linear springs) combined with the introduction of initial geometrical imperfections allowing the structures to adopt alternative stable states in direct response to specific loading conditions.The analysis methods contained within this thesis are currently more advanced than the manufacturing techniques required to realise these designs in the real world. Although, flexible springs are already being cut into stiff plywood panels using living hinges and multi-material 3D printing is commonplace within the maker community, but these techniques have not yet progressed through to the scale and consistency needed to fabricate a large structural element.However, as these manufacturing techniques mature, the work presented within this thesis will provide a solid base from which the effective analysis of multi-stiffness structures will be possible