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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Research on remote control of reconfigurable modular robotic system

Song, Zhanglei 01 August 2009 (has links)
Serial manipulators, which have large work space with respect to their own volume and occupied floor space, are the most common industrial robots by far. However, in many environments the situation is unstructured and less predictable, such as aboard a space station, a nuclear waste retrieval site, or a lunar base construction site. It is almost impossible to design a single robotic system which can meet all the requirements for every task. In these circumstances, it is important to deploy a modular reconfigurable robotic system, which is suitable to various task requirements. Modular reconfigurable robots have a variety of attributes that are well suited to for these conditions, including: the ability to serve as many different tools at once (saving weight), packing into compressed forms (saving space) and having high levels of redundany(increasing robustness). By easy disassembly and reassembly features, this serial modular robotic system will bring advantages to small and medium enterprise to save costs in the long term. This thesis focuses on developing such a serial reconfigurable modular robotic system with remote control functionality. The robotic arms are assembled by PowerCube Modules with cubic outward appearance. The control and power electronics are fully integrated on the connector block inside of the modules. Those modules are connected in series by looping through, and can work completely independently. The communication between robotic arms and PC controller is connected by the Control Area Network bus. CAN protocol detects and corrects transmission errors caused by electromagnetic interference. The local PC can directly control the robotic arm via Visual Basic code, and it can also be treated as server controller. Client PCs can access and control the robotic arm remotely through Socket communication mechanism with certain IP address and port number. A Java3D model is created on the client PC synchronously for customers online monitoring and control. The forward and inverse kinematic analysis is solved by Vector Algebraic Method. The Neutral Network Method is also introduced to improve the kinematic analysis. Multiple-layer networks are capable of approximating any function with finite number of discontinuities. For learning the inverse kinematics neural network needs information about coordinates, joint angles and actuator positions. The desired Cartesian coordinates are given as input to the neural network that returns actuator positions as output. The robot position is simulated using these actuator positions as reference values for each actuator.
2

An improved design concept permitting the dynamic decoupling of serial manipulators taking into account the changing payload / Conception et étude des manipulateurs seriels à dynamique découplée prenant en compte la charge embarquée

Xu, Jiali 21 April 2017 (has links)
Stucture simple, faible coût, grand espace de travail et technologie mature, ces avantages font que les manipulateurs sériels sont largement utilisés dans de nombreux domaines industriels. Avec le développement rapide de l'industrie et les diverses applications des manipulateurs sériels, de nouvelles exigences strictes sont souhaitées, telles que la stabilité robuste, la grande précision de positionnement et la cadence élevée.Un des moyens efficaces pour améliorer les performances mentionnées est la conception de manipulateurs sériels à découplage dynamique. Dans ce cadre, l'objectif de cette thèse est de valider une structure simple permettant de réaliser un découplage dynamique complet des manipulateurs sériels en tenant compte de la charge embarquée.Le chapitre 1 présente les solutions connues et décrit les inconvénients liés aux différentes techniques permettant une simplification de la dynamique des manipulateurs. L'étude de la bibliographie a permis d'affiner les objectifs à atteindre. Le chapitre 2 traite de la conception de manipulateurs sériels réglables à dynamique linéarisée et découplée. Sans la charge embarquée, la méthode développée réalise le découplage dynamique par rotation inverse des bras et par redistribution optimale des masses. La charge embarquée qui conduit à une perturbation au niveau des équations dynamiques dedécouplage est compensée par la commande.Le chapitre 3 envisage un nouveau concept de découplage dynamique qui consiste à relier aux bras initiaux d'un manipulateur sériel, deux bras additionnels pour réaliser un mécanisme Scott-Russell. Les mouvements opposés des bras du mécanisme Scott-Russell associés à une redistribution optimale des masses permettent de supprimer les termes non linéaires des équations dynamiques du manipulateur. Le modèle linéaire et découplé ainsi obtenu permet de tenir compte de la charge embarquée.Dans le chapitre 4, on considère les propriétés de robustesse (incertitudes paramétriques) de quatre modèles de manipulateurs sériels (un manipulateur couplé, un manipulateur découplé par la commande et les deux manipulateurs découplés qui sont issus des chapitres 2 et 3). Les études qualitatives sont effectuées par simulation en utilisant la même loi de commande optimale et la même trajectoire de référence. Les résultats des simulations permettentde conclure sur la robustesse des manipulateurs décrits aux chapitres 2 et 3 par rapport au manipulateur couplé et au manipulateur découplé par la commande.La méthodologie de conception et les techniques de commande proposées sont illustrées par des simulations réalisées à l'aide des logiciels ADAMS et MATLAB. Les simulations ont confirmé l'efficacité des approches développées. / Simple structure, low cost, large workspace and mature technology, these advantages make the serial manipulators are widely used in many industrialfields. With the rapid development of industry and various applications of serial manipulators, new strict requirements are proposed, such as highstability, high positioning accuracy and high speed operation.One of the efficient ways to improve the mentioned performances is the design of manipulators with dynamic decoupling. Therefore, the goal in thisthesis is to find simple structure pennitting to carry out complete dynamic decoupling of serial manipulators taking into account the changing payload.The review, given in Chapter I, sunmarizes the known solutions and discloses the drawbacks of different techniques permitting a simplification of thedynamics of manipulators. lt allows an identification of objectives that are of interest and should be studied \within the framework of this thesis.Chapter 2 deals with the design of adjustable serial manipulators with linearized and decoupled dynamics. Without payload, the developed methodaccomplishes the dynamic decoupling via opposite rotation of links and optimal redistribution of masses. The payload which leads to the perturbation ofThe dynamic decoupling equations is compensated by the optimal control technique.Chapter 3 deals with a new dynamic decoupling concept, which involves connecting to a serial manipulator a two-link group forming a Scott-Russell mechanism combined with optimal redistribution of masses allows the cancellation of the coefficients of nonlinear terms in the manipulator's dynamic equations. Then, by using the control, the dynamicdecoupling taking into account the changing payload is achieved.In chapter 4, robustness properties (parametric uncertainties) of four various models of serial manipulators (one coupled manipulator, one decoupled manipulator by feedback linearization and the two decoupled manipulators that modeled in chapters 2 and 3) are considered. The given comparison performed via simutations is achieved with the same optimal control law and the same reference trajectory. Simulation results allow one to derive robustness assessments of manipulators described in chapters 2 and 3.The suggested design methodology and control techniques are illustrated by simulations carried out using ADAMS and MATLAB software, which have confirmed the efficiency of the developed approaches.

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