Дисертації з теми "Aeronautical assembly"
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1
Haoua, Abdoulaye affadine. "Smart Machining pour l’assemblage aéronautique." Electronic Thesis or Diss., Paris, HESAM, 2023. http://www.theses.fr/2023HESAE090.
Анотація:
Les empilements hybrides composés des couches composites CFRP, du TA6V et d'alliage d'aluminium, appelés multi-matériaux, sont largement utilisés dans les composants aérospatiaux. Le perçage one-shot, au moyen d'une Unité de Perçage Automatique (UPA), de ces empilements pose des défis majeurs en raison de la différence d'usinabilité entre les différents matériaux présents dans l'empilement. Pour répondre aux exigences de qualité, améliorer la tenue des outils et atteindre une pleine productivité lors du perçage de multi-matériaux sur UPA électrique, l’adaptation des paramètres de coupe au cours de l’usinage s’impose. Cela implique une détection fiable des matériaux usinés, la détection de l'usure de l'outil, ainsi que la détection d'incidents (bris d’outil, bourrage copeaux, problème de lubrification, écaillage des arêtes de coupe). Cependant, il n’existe pas actuellement des outils permettant de répondre à ce besoin. Le travail effectué dans cette thèse propose donc des solutions basées sur l’apprentissage automatique pour le développement des méthodologies robustes et fiables d’identification des matériaux, de détection de l'usure de l'outil, ainsi que de détection des incidents pour la mise en en place des stratégies de perçage intelligent (smart-drilling) intégrant de l’usinage auto-adaptatif. Dans un premier temps, une nouvelle approche de détection des incidents a été proposée en s’appuyant sur des données industrielles non étiquetées et des algorithmes de clustering : le K-means et la classification hiérarchique ascendante. Cette approche a permis d’identifier un certain nombre d’incidents et a mis en évidence les difficultés liées au traitement des données industrielles (rareté d’incidents et absence des étiquettes) et les difficultés liées à la définition des paramètres optimaux des algorithmes d’ apprentissage automatique. Dans un second temps, des essais sur un banc expérimental multi-instrumenté dédié et sur des empilements Al7175/CFP et CFRP/Al7175 ont permis de développer et de valider une méthodologie originale d’identification des matériaux basée sur les forêts aléatoires (Random Forest ou RF). Les résultats obtenus en termes de classification par types de matériaux (Al7175, CFRP), ont permis une extension du modèle RF sur différentes configurations d’empilements (CFRP/Al7175/TA6V, TA6V/Al7175/CFRP), avec différents diamètre outils et un large domaine de conditions de coupe. Cette méthodologie permettra d’envisager la mise en œuvre d’un processus d’usinage adaptatif sur UPA électrique pour le perçage de multi-matériaux.Mots clés : Usinage auto-adaptatif, Perçage multi-matériaux, Reconnaissance des matériaux, Forêts aléatoires, Usure outil, Apprentissage non supervisé, UPA électrique, Analyse des signauxHybrid stacks comprising of composite CFRP layers, TA6V, and aluminum alloy, referred to as multi-material, are widely used in aerospace components. One-shot drilling, using an Automatic Drilling Unit (UPA), of these stacks poses major challenges due to the difference in machinability among the various materials within the stack. To meet quality requirements, improve tool life and achieve optimal productivity during the drilling of multi-material stacks with an electric UPA, it is essential to adapt cutting parameters during machining. However, there are currently no tools available to meet this need. This theisis conerns machine learning-based solutions for the implementation of smart drilling strategies incorporating adaptive machining. These solutions focus on the development of robust and reliable methodologies for identifying materials, detecting tool wear, and detecting multi-material drilling-related incidents (tool breakage, chip jamming, lubrication issues, cutting edges chipping). Fristly, a new approach to incident detection was proposed, based on unlabeled industrial data and clustering algorithms: K-means and hierarchical ascending classification. This approach enabled us to identify a number of incidents, and highlighted the difficulties associated with processing industrial data (rarity of incidents and absence of labels) and the difficulties associated with defining the optimum parameters for machine learning algorithms. Subsequently, experiment are performed on an specialized instrumented drilling bench and on Al7175/CFP and CFRP/Al7175 stacks. This led to the development and validation of an original material identification methodology based on Random Forest (RF). The results, in terms of material classification (Al7175, CFRP), enabled the extension of the RF model to different stack configurations with various tool diameters and a wide range of cutting conditions. This methodology will enable the implementation of an adaptive machining process on an electric UPA for multi-material drilling.Keywords : Adaptive drilling, Multi-material stacks drilling, Material recognition, Random Forest, Tool Wear, Unsupervised learning, Electric UPA, Signals analysis
2
Anderson, David Elliott. "Supervisory control algorithms for telerobotic space structure assembly." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/35941.
3
Gralla, Erica Lynn. "Strategies for launch and assembly of modular spacecraft." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/37886.
Анотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2006.Includes bibliographical references (p. 97-101).
NASA's human lunar and Mars exploration program requires a new transportation system between Earth and the Moon or Mars. In recent years, unfortunately, human space exploration programs have faced myriad political, technical, and financial difficulties. In order to avoid such problems, future human space exploration programs should be designed from the start for affordability. This thesis addresses one aspect of affordable exploration programs by tackling the issue of high costs for access to space. While launch vehicle trades for exploration programs are relatively well understood, on-orbit assembly has been given much less attention, but is an equally important component of the infrastructure enabling human access to space. Two separate but related perspectives on in-space assembly of modular spacecraft are provided: first, the coupling between launch vehicle selection, vehicle design, and on-orbit assembly is explored to provide a quantitative understanding of this combined tradespace; and second, a number of on-orbit assembly methods are analyzed in order to understand the potential value of a reusable assembly support infrastructure.
(cont.) Within the first topic, a quantitative enumeration of the launcher-assembly tradespace (in terms of both cost and risk) is provided based on a generalizable process for generating spacecraft modules and launch manifests from a transportation architecture. An optimal module size and launcher capability is found for a sample architecture at 82 metric tons; a 28-mt EELV emerges as another good option. The results show that the spacecraft design, assembly planning, and launcher selection are highly coupled and should be considered together, rather than separately. Within the second topic, four separate assembly strategies involving module self-assembly, tug-based assembly, and in-space refueling are modeled and compared in terms of mass-to-orbit requirements for various on-orbit assembly tasks. Results show that the assembly strategy has a significant impact on overall launch mass, and reusable space tugs with in-space refueling can significantly reduce the required launch mass for on-orbit assembly. This thesis thus examines a broad but focused set of issues associated with on-orbit assembly of next-generation modular spacecraft.
by Erica Lynn Gralla.
S.M.
4
Koonmen, James P. (James Patrick). "Implementing precision assembly techniques in the commercial aircraft industry." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/12120.
5
Hedgecock, Judson C. "Implementation of distributed processing for the beam assembly teleoperator." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/43021.
6
Katz, Jacob G. "Estimation and control of flexible space structures for autonomous on-orbit assembly." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/50599.
Анотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2009.Includes bibliographical references (p. 135-139).
The ability to autonomously assemble large structures in space is desirable for the construction of large orbiting solar arrays, interplanetary spacecraft, or space telescopes. One technique uses free-flying satellites to manipulate and connect elements of the structure. Since these elements are often flexible and lack embedded actuators and sensors, the assembly robot must use its own actuators and onboard measurements to suppress vibrations during transportation maneuvers. This thesis will examine the dynamic modeling of a free-flying robot attached to a flexible beam-like element, vision-based estimation of vibrational motion, and trajectory control for assembly of a space structure.
by Jacob G. Katz.
S.M.
7
Bunn, Jason Chrisotopher. "Evaluation of assembly simulators used in closed loop attitude control system testing." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/47403.
8
McCarthy, Bryan Patrick. "Flight hardware development for a space-based robotic assembly and servicing testbed." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90780.
Анотація:
Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2014.Cataloged from PDF version of thesis. "This material is declared a work of the United States Government and is not subject to copyright protection in the United States."
Includes bibliographical references (pages 161-165).
Robotic assembly and servicing missions in space are becoming increasingly attractive for their potential to expand space capabilities and save money. Future missions may construct large systems on-orbit, service existing space assets, or remove retired satellites from valuable locations in the Geosynchronous orbit, among other things. Due to the high-risk nature of these missions, rigorous test facilities are a necessity. This thesis examines the existing testbeds for robotic assembly and servicing technologies and argues that a new, space-based testbed is necessary. It presents initial ground testing results for applicable control concepts, which also indicate that the dynamic authenticity associated with a six-degree-of-freedom on-orbit testbed is crucial for further development. This thesis then presents the requirements for such a testbed and describes the SPHERES Facility on the International Space Station. The facility, created by members of MIT's Space Systems Laboratory, has many of the desired testbed characteristics and can be easily expanded to meet the requirements through a hardware augmentation known as the Halo. The thesis develops the requirements for the Halo and then steps through the conception, design, and implementation of that hardware, along with the planned operations aboard the International Space Station.
by Bryan Patrick McCarthy.
S.M.
9
Jefferson, Thomas G. "Reconfigurable assembly system design methodology for aerospace wing structures." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/42778/.
Анотація:
The aerospace industry is facing new challenges to meet burgeoning customer demand. An unprecedented number of orders for commercial aircraft has placed great urgency on aerospace manufacturers to make gains in production efficiency. Wing assembly is one such area where cycle times are in the order of hundreds of hours and commissioning cells can take several years which has led to a significant order backlog. In light of these challenges, new techniques are required to bring about greater agility to respond to market changes. Aerospace manufacturers must seize the opportunity to innovate and readdress approaches to ensure their prosperity. Recent research advocates Reconfigurable Assembly Systems (RAS) as a viable solution. A RAS is designed at the outset to change in structure to modify production capacity and functionality to meet new requirements. Yet, adding reconfigurability further increases design complexity. Despite the increased complexity, few formal methodologies exist to support RAS design for aerostructures. A novel RAS design methodology is presented to address the design complexity and the specific needs of Airbus. The methodology is a systems design approach consisting of reconfigurability principles, Axiomatic Design and Design Structure Matrices. Customer needs and existing knowledge are used to systematically specify scalable and customisable functionalities from the outset. These requirements and constraints are then translated into physical system designs modelled using CATIA, a 3D modelling software suite. The design methodology is applied in two case studies for wing assembly to produce full-scale factory designs. The designs are compared with current Airbus baselines in production ramp-up scenarios. The RAS demonstrate capability to change in structure for rapid increase in capacity at comparable cost to fixed systems. Greater capacity and shortened ramp-up time evidently reduces backlog compared to current systems. The first case study focused on technical development of a RAS and found potential ramp-up reduction of 88% and 10% less Capital Expenditure (CapEx) over 10 years. The second case study for a current wing scenario found reductions of 50% to ramp-up and 41% less tooling CapEx compared to a pulse line for a 12-year production cycle. The designs and scenarios were validated in formal Airbus design reviews. The case studies present the first instances of production-scale RAS for aerostructures. The RAS designs are made possible by designing from the outset using a novel design methodology which sets a precedent for the future of aerostructure assembly and opens up new possibilities for future research.
10
Shah, Ankit Jayesh. "Planning for manipulation of interlinked deformable linear objects with applications to aircraft assembly." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105640.
Анотація:
Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 83-87).
Manipulation of deformable linear objects (DLO) has potential applications in the fields of aerospace and automotive assembly. In this paper, we introduce a problem formulation for attaching a set of interlinked DLOs to a support structure using a set of clamping points. The formulation describes the manipulation planning problem in terms of known clamping locations; pre-determined ideal clamping locations on the cables, called "reference points", and a set of finite gripping points on the DLOs. We also present a prototype algorithm that generates a solution in terms of primitive manipulation actions. The algorithm guarantees that no interlink constraints are violated at any stage of manipulation. We incorporate gravity in the computation of a DLO shape and propose a property linking geometrically similar cable shapes across the space of cable length and stiffness. This property allows for the computation of solutions for unit length and scaling of these solutions to appropriate length, potentially resulting in faster shape computation.
by Ankit Jayesh Shah.
S.M.
11
Sanchez, William D. (William David). "State estimation of cooperative satellites for on-orbit assembly and servicing of spacecraft." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112374.
Анотація:
Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 153-157).
The development of robust and routine execution of autonomous space-based proximity operations is a critical need for the future of space exploration and space-based business enterprise. One application of this host of activities, which includes rendezvous, capture, and docking, is on-orbit assembly and servicing of spacecraft. It is believed that the maturation of this technology could usher in a new era of space technology featuring modular construction of large spacecraft or habitats for exploration and tourism, assembly of large-aperture space telescopes unconstrained by launch vehicle size, and reconfigurable structures for mission adaptability. Furthermore, this technology could extend to capture and repair high asset spacecraft by replacing modular components, all without the need to risk human lives. This thesis seeks to contribute to the development of this technology by focusing on one of its most critical aspects: robust state estimation between the autonomous agents. Several estimation frameworks exist that can be applied. However, two state estimators were specifically chosen, implemented, verified, and validated for reasons discussed in the text. First, a practical method of implementation of an Unscented Kalman Filter for two active, cooperative, autonomously docking satellites that overcomes latency issues from low frequency vision-based relative-pose measurements is presented. Second, a factor graph based incremental smoothing estimator for the same application is implemented, which can be shown to provide robustness to several failures characteristic of the filtering framework. A detailed analysis enumerating the strengths and weaknesses of the two frameworks is provided, as well as the verification and validation of the two estimators via the SPHERES testbed from both a 3-DOF planar air bearing facility and the playback of data sets collected from the International Space Station 6-DOF test environment.
by William D. Sanchez.
S.M.
12
Jarrett, David B. "Time-and-motion correlation of extravehicular space structure assembly with neutral buoyancy simulation." Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/15029.
Анотація:
Thesis (M.S.)--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERO.
Bibliography: leaves 82-83.
by David B. Jarrett.
M.S.
13
Mohan, Swati. "Reconfiguration methods for on-orbit servicing, assembly, and operations with application to space telescopes." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/39706.
Анотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007.Includes bibliographical references (p. 115-118).
Reconfiguration is an important characteristic in furthering on-orbit servicing, assembly, and operations. Previous work has focused on large assemblers manipulating small payloads, where the dynamics of the assembler is not significantly changed. This work seeks to identify the impact of reconfiguration on maneuver performance. Reconfiguration is considered in two categories: implementation and application. Implementation of reconfiguration consisted of developing a method for defining and updating a configuration, implementation on the SPHERES testbed, and execution of tests (in simulation and on the International Space Station) to assess the control performance improvement after reconfiguration. Four applications were considered in this work, two hardware applications and two systems applications modeled through simulation. The objective of the SWARM application was to demonstrate autonomous assembly capability through docking and undocking maneuvers. The objective of the SIFFT application was to demonstrate formation reconfiguration capability, through the expansion and rotation of an equilateral triangle of three satellites. The objective of the systems applications was to determine the impact of re-configuration in a larger mission context.
(cont.) One application, Mass Property Update, considered how the choice of method for obtaining the mass property information impacts operations. The other application, Modularity Analysis, considered how the implementation of modularity is driven by the mission objectives. Overall, this work has served to demonstrate the control impact of reconfiguration though implementation on the SPHERES testbed. This implementation was used on two hardware applications to determine the performance of reconfiguration for assembly and formation reconfiguration missions. Also, the impact of reconfiguration has been studied in the broader systems context. The choice of method of mass property update was demonstrated to have an impact on operations, in terms of reliability and mass. Finally, the method incorporation of modularity for purposes of on-orbit servicing and assembly was demonstrated to be driven by mission design parameters.
by Swati Mohan.
S.M.
14
Mohan, Swati. "Quantative [sic] selection and design of model generation architectures for on-orbit autonomous assembly." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59664.
Анотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 243-251).
On-orbit assembly is an enabling technology for many space applications. However, current methods of human assisted assembly are high in cost and risk to the crew. Thus, there is a desire to automate the on-orbit assembly process using robotic technology. Automation introduces additional challenges in the design of the assembly, particularly within the control systems. During an assembly sequence, an assembler robot can undergo multiple reconfigurations of its geometry and dynamics as it attaches to and releases from individual modules. The particular problem addressed in this thesis is how to account for mass and stiffness property variations that occur with changes in configuration. Proper model generation for each configuration is critical to maintain control system stability and efficiency. This thesis explores two specific challenges associated with this problem: (1) the design of a model generation architecture to where module mass property information is known, but specific configurations are unknown; and (2) the selection of a model generation architecture that is appropriate for a given assembly architecture. Literature review of the possible model generation architectures revealed a gap in the literature, when models are aggregated online based on module mass property information. The challenge is resolved through the design of an architecture, called Online Model Calculation. Online Model Calculation uses module information obtained at the time of attachment to generate the model for the current configuration online. This is accomplished through the parameterization of the control algorithms with respect to a property vector. The property vector contains mass property information (ex. mass, inertia) that is used to generate the model. The design of Online Model Calculation, both in terms of framework and algorithm parameterization, is successfully implemented and validated on hardware. Results show a tracking error performance improvement when the correct model of the system is used in the control system over an unupdated model of the assembler along. Online Model Calculation balances a priori knowledge about the possible configurations with identification of the model online. The challenge of selecting a model generation architecture is accomplished through the development of a process that downselects feasible architectures into a single optimal architecture. This process is based on a set of generalized, quantitative metrics that are used to compare architectures from the perspectives of the control system, spacecraft, and assembly operation levels. It is exercised on three case scenarios, using a simulation tool that is developed to evaluate the model generation architecture metrics for a given assembly architecture. Results clearly show that for different assembly scenarios, different model generation architectures perform best. The quantification of this performance difference and the process for selecting the appropriate architecture constitute a key contribution of this work.
by Swati Mohan.
Ph.D.
15
Sternberg, David Charles Ph D. Massachusetts Institute of Technology. "Development of an incremental and iterative risk reduction facility for robotic servicing and assembly missions." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90611.
Анотація:
Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2014.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 138-142).
A means for reducing the risk for an on-orbit robotic servicing and assembly mission through the development of a series of testbeds that build successively upon one another is investigated. Robotic Servicing and Assembly (RSA) missions are believed to enable life extension programs for existing spacecraft while also enabling much larger and more complex satellites to be developed through on-orbit construction. Unfortunately, many of the new and innovative technologies required for RSA to be economically and technically feasible are still in their formative development stages. Consequently, such RSA missions are highly risk prone. This thesis investigates the development of an incremental and iterative testing facility which can be used to reduce these RSA risks by conducting demonstration testing in authentic operational environments while leveraging existing infrastructures to reduce the costs associated with testing. The Defense Advanced Research Project Agency's (DARPA) Phoenix project, a satellite repurposing mission, serves as an example of a full-scale flight mission requiring risk-reduction testing. The thesis presents research that shows how the newly developed testing facility, which expands on the Synchronized Position Hold Engage and Reorient Experimental Satellites (SPHERES) facility, can reduce the risk of many technologies required for Phoenix. In particular, testing is discussed and analyzed for the risk reduction of resource aggregation and physical reconfiguration technologies. This testing is both incremental and iterative in nature as part of two ground test programs and a flight program aboard the International Space Station. The testing progression matures these technologies from base principles tested in the ground environment at the MIT Space Systems Laboratory to the planned implementation aboard the International Space Station prior to the final flight mission. The newly developed testing facility is small in scale as compared to the final RSA flight satellites, so newly developed scaling laws are presented. This process relies on the scaling of testbed results using the combined application of hybrid scaling laws and nondimensional parameters. In doing so, the results from the new testing facility can be applied to the Phoenix mission to raise the probability of mission success.
by David Charles Sternberg.
S.M.
16
Sidwell, Carroll Vincent 1972. "On the impact of variability and assembly on turbine blade cooling flow and oxidation life." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/17814.
Анотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2004.Includes bibliographical references (leaves 77-79).
The life of a turbine blade is dependent on the quantity and temperature of the cooling flow sup- plied to the blade. The focus of this thesis is the impact of variability on blade cooling flow and, subsequently, its impact on oxidation life. A probabilistic analysis is performed on a commercial jet engine to quantify the variability in blade flow and oxidation life due to variability in ambient conditions, main gaspath conditions, the cooling air delivery system, and the flow capability of the blade internal cooling passages. The probabilistic analysis is used to demonstrate that every blade in a turbine row must be individually modeled in order to accurately estimate the distribution of blade-row oxidation life for a population of jet engines. In particular, since the oxidation life of a blade row is limited by the highest temperature (and therefore lowest-flowing) blades, every blade must be individually represented to correctly model (1) the probability of observing (within a row) a blade with a low coolant flow capability, and (2) the flow rate (and therefore the metal temperature and life) of these passages. A simplified flow network model of the cooling air supply system and a row of blades is proposed which agrees qualitatively and quantitatively with the more complex flow network model of the entire jet engine. Using this simplified model, the controlling parameters which affect the distribution of cooling flow in a blade row are identified. Finally, a selective assembly method is proposed to decrease the impact of blade passage manufacturing variability on blade flow. The method classifies blades into groups based on passage flow capability and assembles rows from within the groups. As a result, the flow and the
(cont.) oxidation life improve for the majority of blade rows, while segregating low-flow blades into sets that are no worse than random assembly. Alternatively, selective assembly can be used to allow blades to withstand increased turbine inlet temperature while maintaining the maximum blade metal temperature at random-assembly levels.
by Carroll Vincent Sidwell.
Ph.D.
17
Unhelkar, Vaibhav Vasant. "Introducing mobile robots on the automotive final assembly line : control, sensing and human-robot interaction." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98814.
Анотація:
Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 101-107).
Traditionally, robots in manufacturing have been deployed in caged, static and predictable environments. Advances in robotics are enabling industrial robots to emerge from these traditional habitats, and enter the final assembly to work along side humans. My thesis contributes to this effort through development of a mobile robot capable of operating on final automotive assembly lines to assist humans. Several algorithmic as well as design challenges exist when mobile robots enter the unpredictable, human-centric and time-critical environment of final assembly. My primary focus is on achieving autonomous mobility, a precursor for introducing robots to operational factory floors. Automotive assembly lines present a distinct challenge in form of surfaces that are dynamic, i.e., the conveyor belts which ferry cars in the factory. I develop a control strategy to enable autonomous navigation on such dynamic surfaces, and design a sensing module capable of detecting the conveyor belts. The designed system is tested in simulation, implemented on hardware and evaluated on an operational, automotive factory floor. Evaluation in factory establishes preliminary success in the designed robotic system. Interesting, qualitative observations while introducing a robot in a real environment also emerge, and motivate need for enhancing the interaction capability of robots for time-critical tasks in human-centric environments. Towards this, we carry out a human subject experiment (N = 24) comparing the performance of the robot to that of a human assistant in an analogue assembly line environment. Results from the experiment provide a better understanding of the factors that impact fluency of interaction and inform the design of a more effective mobile robotic assistant. This work introduces mobile robots on the automotive assembly lines right next to people, thereby paving the way for utilizing them to assist busy, human associates in the myriad tasks involved in final assembly of cars.
by Vaibhav Vasant Unhelkar.
S.M.
18
Zhang, Zhe. "Development and validation of microvibration models for a satellite reaction wheel assembly." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/348811/.
Анотація:
Microvibrations are a critical concern on satellites equipped with instruments with high stability requirements. Amongst many sources of microvibration onboard, reaction wheel and momentum wheel assemblies are often considered the most significant. This thesis presents the development and validation of microvibration models for a cantilever configured wheel assembly designed with a soft-suspension system. Wheel assembly induced microvibrations under hard-mounted and coupled boundary conditions are studied. In particular, the wheel assembly semi-analytical microvibration model in a hard-mounted boundary condition is developed with harmonic excitations and the traditionally ignored broadband noise excitations are included. Some peculiar dynamics such as nonlinearity in the motor and high damping of the soft-suspension system are observed from the hard-mounted measurements conducted on a bespoke dynamometer. Modeling strategies for these peculiar dynamics are developed and implemented in the wheel assembly microvibration modeling. This includes a systematic approach to extract stiffness and damping values of the suspension system, considering nonlinearity and high damping from measurements. The microvibrations produced by the wheel assembly in a coupled boundary condition are studied using a seismic mass to support the wheel assembly. A coupled microvibration measurement system, which allows the wheel assembly interface loads to be reconstructed by measuring the response accelerations on the seismic mass, is designed, built and validated. In addition, the wheel assembly driving point static and dynamic accelerance are measured and analytical expressions of the driving point dynamic accelerance are derived. The coupled microvibrations are predicted with wheel assembly static accelerance, dynamic accelerance and the standard method (i.e. no wheel accelerance). The predicted results have shown that the method developed in this thesis which uses the wheel assembly dynamic accelerance accurately simulates the microvibrations observed in practice.
19
Terán, Espinoza Antonio. "Probabilistic and learning approaches through concurrent parameter estimation and adaptive control for in-space robotic assembly." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112480.
Анотація:
Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 143-148).
Autonomous and multi-agent space operations within the context of in-space robotic servicing, assembly, and debris removal have received particular attention from both research and industry communities. The presence of uncertainties and unknown system parameters amongst these missions is prevalent, as they primarily deal with unknown or uncooperative target objects, e.g., asteroids or unresponsive, unsupervised tumbling spacecraft. To lower the inherent risk associated with these types of operations, possessing an accurate knowledge of the aforementioned characteristics is essential. In order to achieve this, approaches that employ a unified framework between parameter estimation and learning methodologies through a Composite Adaptation (CA) structure are presented. Furthermore, to evaluate the likelihood of mission success or objective completion, a probabilistic approach upon the system's operations is introduced; by employing probability distributions to model the control system's response and pairing these with the analysis of objectives' requirements and agents' characteristics, the calculation of on-board feasibility and performance assessments is presented. A formulation for the estimator and the controllers is developed, and results for the adaptive approach are demonstrated through hardware implementation using MIT's Synchronized Position Hold Engage Reorient Experimental Satellites (SPHERES) ground testing facilities. On-orbit test session data is analyzed, and further improvements upon the initial learning approach are verified through simulations.
by Antonio Terán Espinoza.
S.M.
20
Wolters, James Aaron 1966. "Optimizing the assembly sequence of an aerospace manufacturing process." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/34707.
Анотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics; in conjunction with the Leaders for Manufacturing Program, Massachusetts Institute of Technology, 2000.Also available online at the MIT Theses Online homepage
Includes bibliographical references (p. 65-66).
The 1990's were a time of downsizing and consolidation for much of the defense aerospace industry. Many defense contractors sought to integrate lean manufacturing principles and techniques into their business, as a means of becoming more cost-competitive in bidding for a shrinking defense budget, and to enable moves into commercial product lines. UTC-Sikorsky Aircraft Company began a series of restructuring and re-engineering initiatives in the late 1990's aimed at addressing these issues. This internship focused on cost reduction in Sikorsky's main product line - the UH-60 Blackhawk helicopter. The final assembly line for the UH-60 was subject to cost and schedule overruns, along with high inventory levels. The assembly line was also characterized by a high degree of variability, and a major source of variability was believed to be the lack of a defined and repeatable sequence for the installations that comprise final ass~mbly. The introduction of an optimized assembly sequence, and subsequent adoption for daily use by shop floor personnel, was expected to reduce variability and improve performance. The use of a sequence itself was expected to produce the following benefits: 1. Provide a significant improvement in the use of visual tools for line management. 2. Help capture valuable information about installations from workers, and then transfer this knowledge to management, planners, and new workers as personnel are rotated through the factory. 3. Enable significant inventory reduction through introduction of a just-in-time (JIT) material delivery methodology, by linking material delivery to the order in which it is consumed. Implementation was expected to aid in identifying the shortcomings and limitations of the systems that have prevented the use of a sequencing methodology in the past. More importantly, it would elevate the importance of addressing and solving these issues as a means to achieve company-wide goals for cost and inventory reduction. Through implementation of this sequence, key issues were identified: -- JIT inventory levels are difficult to achieve in a large, complex aerospace assembly process, -- The manufacturing system, along with systems and processes which support it, must be capable of supporting JIT prior to implementation (and may need to be redesigned to do so), and -- Process re-engineering to support JIT is best accomplished through a combination of top-down and bottom-up change processes.
by James Aaron Wolters, II.
S.M.
21
Kamran, Skander, and Alexander Mäkelä. "Prerequisites for Automatically Creating Work Instructions in Augmented Reality for Assembly of Gripen E : a case study at Saab Aeronautics." Thesis, Linköpings universitet, Industriell Produktion, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-166536.
Анотація:
This thesis work has been carried out at the company Saab AB Aeronautics, which manufactures the military aircraft Gripen E. Today, the company uses 3D work instructions for assembly of Gripen E, which is displayed on a computer screen for the shop floor workers. The company has an interest in investigating whether today's work instructions can be visualized in an Augmented Reality interface by reusing available data. This work has been limited to studying wire harness assembly, which is a main part of the final assembly. The methodology case study in combination with the method Requirements Engineering has been used to analyze the company's possibilities. Data collection has been conducted with internal interviews, studying internal materials and internal courses. The result chapter contains two parts, where the first part presents a situation analysis of how today's work instructions are created in the software DELMIA and what data that is needed. The second part presents a requirements specification for an Augmented Reality Work Instruction for assembly of Gripen E. In the discussion, the situation analysis is compared with the requirements to answer which data that could be reused for creating Augmented Reality Work Instructions and what challenges that may arise. This study shows that the company has prerequisites for creating work instructions in Augmented Reality, as there is available data containing 3D models structured according to an assembly sequence with associated descriptive information.
22
Viggh, Herbert E. M. "Artificial intelligence applications in teleoperated robotic assembly of the EASE space structure." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/39358.
Анотація:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, and Dept. of Electrical Engineering and Computer Science, 1988.Bibliography: leaf 197.
by Herbert E. M. Viggh.
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, and Dept. of Electrical Engineering and Computer Science, 1988.
23
Durham, Bryce J. (Bryce James). "Determining appropriate levels of robotic automation in commercial aircraft nacelle assembly." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90609.
Анотація:
Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, 2014. In conjunction with the Leaders for Global Operations Program at MIT.Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2014. In conjunction with the Leaders for Global Operations Program at MIT.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
36
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 71-73).
This thesis examines the application of reconfigurable industrial robotics in the assembly of the engine nacelle inlet for a commercial aircraft. In addition to addressing the achievable level of automation, this thesis also reviews the evaluation of robotics vendor proposals and the accompanying financial justification requisite for implementation. The aircraft industry has long been dominated by manual fabrication and assembly methods. Variability in human skill, however, results in defects, rework, and reduced production throughput. One approach to reduce variability, decrease cycle time, and increase throughput is the implementation of robotic automation for various assembly tasks. Low aircraft production volumes have made it difficult to justify large investments in robotic automation. Decreasing cost and increasing capability of industrial robotics, however, are making investment more palatable. The excellent repeatability of robotic automation can significantly reduce individual task times for a wide range of operations. Standard automated task times are 60{85% lower than standard manual task times for drill and fasten operations which represent the greatest opportunity for cycle time improvements because typical aircraft assembly requires tens of thousands of holes and fasteners. The optimal level of automation is a balance among decreasing manual touch time, improving production capacity, and increasing automation costs. A semi-automated solution is shown to reduce manual touch time by 70% and total touch time by 30%. The implementation of this solution requires an investment of tens of millions of dollars and results in present value savings of hundreds of millions of dollars for the program lifetime.
by Bryce J. Durham.
M.B.A.
S.M.
24
Coleman, Robert Mark 1962. "The effects of design, manufacturing processes and operations management on the assembly of aircraft composite structure." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/42495.
Анотація:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1991 and Thesis (M.S.)--Sloan School of Management, 1991.Includes bibliographical references (leaf 104).
by Robert Mark Coleman.
M.S.
25
Silva, Bruno Jensen Virginio da. "Programação de montagens em gabaritos com restrições de adjacência na indústria aeronáutica." Universidade Federal de São Carlos, 2010. https://repositorio.ufscar.br/handle/ufscar/3648.
Анотація:
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Previous issue date: 2010-12-03Financiadora de Estudos e Projetos
This work deals with a production scheduling problem that appears in the aeronautics industry, involving special structures called assembly fixtures, composed of several workstations in parallel to assemble parts of the aircrafts. Tasks should be scheduled to be performed in these workstations in order to minimize the quantity of manpower needed to do the assembly and determine the production capacity of the assembly fixture, which means minimizing the makespan (the total time needed to finish the tasks). However, in addition to the usual constraints such as due dates and precedence among tasks, there are also constraints that prevent two tasks to be performed at the same time in two adjacent workstations on the assembly fixture. The assembly and the teams who work there are in continuous improvement of assembling processes, according to the cumulative production increases and the learning curve is traversed. The learning curve was divided in four stages with specific characteristics in each. Mixed integer linear programming models are proposed to represent the production scheduling problem of each stage, based on practical cases studies of assembly fixtures scheduling in an aeronautics company. Those models are solved using a modeling language and optimization software. The solutions are analyzed and compared and based on then, it is evaluated how the learning curve affects the airplane production over time and it is shown, in the results, that there exists potential of improvement in the use of assembling resources, using production scheduling and levelling the resources.
Este trabalho aborda um problema de programação da produção que ocorre na indústria aeronáutica, envolvendo estruturas especiais de montagem chamadas gabaritos, compostas de diversos postos de trabalho em paralelo para montar partes das aeronaves. Tarefas devem ser programadas para serem executadas nestes postos de trabalho de maneira a minimizar a quantidade total de mão de obra necessária para realizar a montagem em questão e determinar a capacidade de produção do gabarito, ou seja, minimizar o makespan (tempo total para executar as tarefas). Porém, além das restrições usuais, como prazos de entrega das tarefas e precedências entre as tarefas, existem também restrições que impedem que duas tarefas possam ser executadas ao mesmo tempo em dois postos de trabalho adjacentes no gabarito. A montagem e as equipes que nela trabalham estão em melhoria contínua dos processos de montagem, conforme a produção acumulada aumenta e a curva de aprendizagem é percorrida. A curva de aprendizagem foi dividida em quatro fases com características específicas em cada uma. Propõem-se modelos de programação linear inteira mista para representar o problema de programação em cada uma das fases, com base em estudos de casos práticos de programação de gabaritos de montagem de uma empresa aeronáutica. Estes modelos são resolvidos utilizando-se uma linguagem de modelagem e um software de otimização. As soluções encontradas são analisadas e comparadas e com base nelas, avalia-se como a curva de aprendizagem afeta a produção de aviões ao longo do tempo e demonstra-se que existe potencial de melhoria no uso dos recursos de montagem, utilizando programação da produção e nivelamento dos recursos.