Parallel robotic manipulators are a specific type of robot that has multiple limbs which are ultimately connected to a moving body. Within this regime, there are several sub-classes of robots characterized by certain inherent traits. Common to all sub-classes is the ability to articulate the moving platform by actuating each of the limbs. In general, it has been shown that these types of robotic manipulators possess several types of advantageous properties. Some of these properties are: good dynamic character, high stiffness, high precision, large payload to weight ratio, and high speed. Flexible and reconfigurable manufacturing regimes are new manufacturing system paradigms that aim at achieving cost-effective and rapid system changes. Essentially, a system classified as flexible or reconfigurable would be one that is adaptive to change in the market without the need to re-design or re-develop its components. The advantage of such a system is in theory very large. To date, there has been some enhancements made in the area, however there are still many open aims and possible improvements to be investigated. Much of which aims at furthering the concepts from theory to practical applications. The main objective of this dissertation is to enhance the knowledge base in flexible and reconfigurable systems through parallel robotics. Specifically, by utilizing new ideas in parallel robotics tailored to these manufacturing regimes, significant improvements in the knowledge base are attained. These can be classified under one specific regime of parallel robotics and further categorized as passive, semi-active, and active (adaptive). This thesis first focuses on a new design methodology related to flexible and reconfigurable manufacturing. Essentially, the method proposes a systematic approach to recon figure the dynamic properties of robotic devices for various functional requirements that would be part of a flexible manufacturing situation. The method is tested on an example structure and results indicate that the proposed reconfiguration method outperforms existing devices. Next, this dissertation focuses on the design of new robotic architectures that are more adaptive. Specifically, the goal is to achieve structures that can be adaptive in real-time. Existing structures are only reconfigurable passively and need to stop operation in order to reconfigure manually. To this end, a hybrid structure that is semi-active reconfigurable is first investigated. It is dubbed the ReSl-Bot. A complete engineering analysis and design is conducted illustrating its properties. To take this one step further, a novel class of hybrid adaptive parallel robots is then proposed. A 6-DOF robot belonging to this class called the HAPM mk.1 is studied in detail. It is effectively shown that this novel design has the ability to adapt properties actively. This type of adaption could be used for the performance enhancement in many applications, particularly for flexible manufacturing. Properties such as DOF, stiffness, dexterity, precision, kinetics, energy consumption, backlash, etc. could potentially be altered for varying applications and requirements. Notably, a complete theoretical analysis is conducted, ending with analytical dynamics and control.

A failure recovery methodology based on decomposing the platform task space into the major and secondary subtasks is proposed which enables the manipulator to minimize the least-squares error of the major subtasks and to optimize the secondary criterion. A methodology for wrench recovery of parallel manipulators is proposed so that the platform task is divided into the recoverable and non-recoverable subtasks based on the number and type of actuator failures, manipulator configuration and task/application purposes. It is investigated that when the Jacobian matrix of the manipulator is of full row-rank and the minimum 2-norm of the joint velocity vector satisfies the velocity limits of the joints, the full recovery of the platform twist will be provided. If the full recovery of the platform twist cannot be achieved, the optimization method followed by the partitioned Jacobian matrix is used to deal with the failure recovery. It is verified that the optimization method recovers as many as possible components of the platform velocity vector when the objective function, 2-norm of the overall velocity vector of the healthy joints, is minimized. To model uncertainty in the kinematic parameters, the interval analysis is proposed. Different interval-based algorithms to enclose the solution set to the interval linear systems are applied and the solution sets are compared. A novel approach in characterizing the exact solution of the interval linear system is proposed to deal with the failure recovery of parallel manipulators with velocity limits of the joints and uncertainty in the kinematic parameters. Simulation results show how the solution sets of the joint velocity vector are characterized by introducing uncertainties in the kinematic parameters. The calculation of the exact solution takes more computation time compared to the interval-based algorithms. However, the interval-based algorithms give the wider solution box with less computation time. The effect of variations and/or uncertainties in design parameters on the workspace of wire-actuated parallel manipulators without and with gravity is investigated. Simulation results show how the workspace size and shape are changed under variations in design parameters. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2014-03-09 16:18:12.74

The goal of the research of this Dissertation is using actuation redundancy to reduce backlash in parallel manipulators (PMs.) Initially, 3-RRR and 3-RPR PM layouts where 3 is the number of branches, R is a revolute joint and P is a prismatic joint, are introduced. Actuated joints will later be underlined in the PM desciptions. A method for determining PM working area for rotated payload platforms, based on a mechanism inversion, is presented. Force solutions for non-redundantly actuated 3-RRR, 3-RRR, 3-RPR and 3-RPR PMs are formulated in terms of screw coordinates. The reciprocal product of screw coordinates is demonstrated to be invarient under changes in reference location and orientation. As examples, the PMs execute basic circle, logarithmic spiral and arc displacement and force trajectories. All non-redundantly-actuated PMs, encounter two backlash-prone zero-actuator-output configurations when executing any of the trajectories. Therefore, non-redundantly actuated PMs are found inadequate for precision applications. Force-uncertainties, where PMs cannot sustain or apply forces in uncertain directions, are examined. For typically actuated 3-RRR and 3-RPR PMs, force uncertainties are identified using screw system arguments based on the existance of 3 actuated forces forming degenerate (rank = 2) planar pencils of forces. These degenerate force pose make arbitrary force and moment application impossible and cause singularities in the force solutions. The working area of the 3-RRR PM is found compatible with all trajectories. This compatibility is due to zero minimum branch length being possible with the limitless angular displacements possible with stacked R joints. In comparison, the 3-RPR PM with minimum joint lengthes imposed on the P joints, has a smaller working area, and is not compatible with any of the trajectories. A P joint modification allowing relative length minimums of zero and a compatible working area identical to the 3-RRR PM, is considered. To address inadequacies, symmetric actuation-redundant 3-RRR and 3-RPR PMs are considered. Pseudo (right Moore-Penrose) inverse of the 3×6 ARS (associated reciprocal screw) matrix is considered to solve for the required actuation. This solution, while providing a minimum 2-norm of the vector of required actuator outputs, does not reduce backlash-prone configurations with all actuators still having two backlash-prone zero-output configurations. An algorithm for reducing backlash, using MATLAB’s constrained optimization routine FMINCON is applied. Minimizing the 2-norm of the vector of actuator outputs, subject to the backlash-free constraint of having outputs ≥ 0 or ≤ 0 depending on the initial values, is considered. Actuators providing the best conditioned ARS matices are utilized for the particular solutions. / Graduate

Un manipulateur parallèle à mobilité réduite a moins de six degrés de liberté et présente généralement différents types de mouvement connus sous le nom de modes d'opération. Ainsi, ce type de manipulateur peut être classifié comme reconfigurable selon sa capacité de transition entre les différents modes d'opération. Cette thèse de doctorat s'articule principalement autour de l'analyse cinématique de manipulateurs parallèles à mobilité réduite, de manipulateurs parallèles en série obtenus à partir de leur empilement en série et de mécanismes conformes conçus à partir de leurs configurations singulières à contraintes. La transformation cinématique de Study est utilisée pour dériver les équations algébriques de contraintes. Ensuite, elles sont interprétées à l'aide d'outils de géométrie algébrique pour effectuer des analyses de mobilité, de cinématique et de singularité. Les techniques de ‘‘screw theory’’ et ‘‘line geometry’’ sont utilisées à côté de l'approche algébrique au besoin. / A lower mobility parallel manipulator has less than six degrees of freedom and usually exhibits different motion types known as operation modes. Thus, it can be classified as reconfigurable on account of its ability to transition between different operation modes. This doctoral thesis mainly revolves around the kinematic analysis of some lower-mobility parallel manipulators, series-parallel manipulators obtained from their serial stacking and compliant mechanisms designed using their constraint singular configurations. Study's kinematic mapping is used to derive the algebraic constraint equations. They are further interpreted using algebraic geometry tools to perform mobility, kinematic and singularity analysis. Screw theory and line geometry techniques are used adjacent to algebraic approach wherever necessary.

In this thesis, the redundancy resolution and failure analysis of Cable-Driven Parallel Manipulators (CDPM) are investigated. A CDPM consists mainly of a Mobile Platform (MP) actuated by cables. Cables can only apply force in the form of tension. So, to design a fully controllable CDPM, the manipulator has to be redundantly actuated (e.g., by using redundant cables, external force/moment or gravity). In this research, the redundancy resolution of planar CDPMs is investigated at the kinematic and dynamic levels in order to improve the manipulator safety, reliability and performance, e.g., by avoiding large tension in the cables that may result in high impact forces, and avoiding large MP velocities that may cause instability in the manipulator, or on the contrary, by increasing the cable tensions and the stiffness for high-precision applications. The proposed approaches are utilized in trajectory planning, design of controllers, and safe dynamic workspace analysis where collision is imminent and the safety of humans, objects and the manipulator itself are at risk. The kinematic and dynamic models of the manipulator required in the design and control of manipulators are examined and simulated under various operating conditions and manufacturing automation tasks to predict the behaviour of the CDPM. In the presented research, some of the challenges associated with the redundancy resolution are resolved including positive tension requirement in each cable, infinite inverse dynamic solutions, slow-computation abilities when using optimization techniques, failure of the manipulator, and elasticity of cables that has a significant role in the dynamics of a heavy loaded manipulator with a large workspace. Optimization-based and non-optimization-based techniques are employed to resolve the redundancy of CDPM. Depending on the advantages and disadvantages of each method, task requirements, the used redundancy resolution technique, and the objective function suitable optimization-based and non-optimization-based routines are employed. Methodologies that could combine redundancy resolution techniques at various levels (e.g., position, velocity, acceleration, and torque levels) are proposed. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2012-09-26 22:39:34.35

Orientador: João Mauricio Rosario / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-12T18:15:19Z (GMT). No. of bitstreams: 1 LaraMolina_FabianAndres_M.pdf: 3777126 bytes, checksum: 5d2bb864ea5a4dc9fb76ddeeeb83c38f (MD5) Previous issue date: 2008 / Resumo: O presente trabalho recopila e aplica conceitos concernentes à modelagem dos manipuladores paralelos, desta maneira é proposta um ambiente de simulação para manipuladores paralelos aplicada à Plataforma Stewart. O manipulador paralelo de seis graus de liberdade - Plataforma Stewart é utilizado em aplicações que requerem alto desempenho de posicionamento: alta rigidez, alta razão capacidade de carga - peso do manipular, alta exatidão no movimento. Entre as aplicações nas quais se tem utilizado a Plataforma Stewart estão: simuladores de vôo, manipuladores cirúrgicos, máquinas ferramentas CNC, sistemas de locomoção bípedes, etc. São enfatizados aspectos concernentes à modelagem cinemática e dinâmica deste manipulador. A partir do modelo é proposta a simulação e controle de posição no espaço das juntas em MATLAB - SimulinkTM. A validação da simulação é feita mediante um estudo de casos / Abstract: The present work involves and applies parallel manipulator design concepts; therefore it is proposed a parallel manipulator design methodology applied to Stewart Platform. In this research project, it is modeled, simulated and analyzed the six degrees of freedom parallel manipulator - Stewart Platform. This system is used on applications with high position performance: high stiffness, high useful load - manipulator weigh and high accuracy. The Stewart Platform has been applied in: flight simulators, surgery manipulators, CNC machines, biped locomotion systems, etc. In this work are emphasized on Stewart Platform cinematic and dynamic modeling concepts. Based on manipulator model is proposed the simulation and joint space position control in MATLAB - SimulinkTM. The simulation is validated thought a case study / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

No description available.

La popularité des robots parallèles s’est considérablement accrue lors des dernières décennies. Cette popularité a été stimulée par les nombreux avantages qu’offrent les robots parallèles par rapport à leurs homologues traditionnels sériels concernant certaines applications industrielles nécessitant de fortes accélérations et une bonne précision. Toutefois, afin d'exploiter pleinement leur potentiel et de tirer le meilleur de leurs capacités, un long chemin reste encore à parcourir. En plus de la conception mécanique, l'étalonnage et l'optimisation de la structure, le développement d’une commande efficace joue un rôle primordial dans l’amélioration de la performance globale des robots parallèles. Cependant, ces derniers sont connus par leur dynamique fortement non linéaire qui s’accroît considérablement lorsque de fortes accélérations sont sollicitées conduisant à des vibrations mécaniques. En outre, les incertitudes sont abondantes dans ces systèmes en raison des hypothèses simplificatrices de modélisation, l'usure des composants du robot et les variations de l'environnement. De plus, leur dynamique couplée et la redondance d'actionnement dans certains mécanismes donnent lieu à des problèmes de commande complexes et difficiles à gérer. Par conséquent, les stratégies de commande développées pour les robots parallèles devraient tenir compte de tous les enjeux et défis mentionnées précédemment. L'objectif principal de cette thèse réside dans la proposition de nouvelles stratégies de commande adaptatives pour les robots parallèles tenant compte de leurs caractéristiques et particularités afin d'améliorer leurs performances de suivi de trajectoires. En outre, les stratégies de commande développées devraient être validées d'abord en simulation, puis à travers des expérimentations temps-réel sur les robots parallèles à notre disposition. Dans ce contexte, trois contributions majeures sont proposées dans le cadre de cette thèse. Tout d'abord, une nouvelle classe de contrôleurs adaptatifs avec des gains de retour non linéaires temps-variant est proposée. La deuxième contribution réside dans le développement d’une version adaptative de la commande robuste RISE. Pour la troisième contribution, la stratégie de commande adaptative L1, récemment développée, est appliquée pour la première fois sur un robot parallèle, suivie de deux nouvelles extensions basées-modèle. Des simulations numériques ainsi que des expérimentations temps-réel sur différents prototypes de robots parallèles sont présentées et discutées. Tous les contrôleurs proposés sont validés pour différents scénarios permettant ainsi de montrer leur pertinence et efficacité. / Parallel Kinematic Manipulators (PKMs) have gained an increased popularity in the last few decades. This interest has been stimulated by the significant advantages of PKMs compared to their traditional serial counterparts, with respect to some specific industrial tasks requiring high accelerations and accuracy. However, to fully exploit their potential and to get the most of their capabilities, a long path is still to be covered. In addition to mechanical design, calibration and optimization of the structure, efficient control development plays an essential role in improving the overall performance of PKMs. However, PKMs are known for their highly nonlinear dynamics which increases considerably when operating at high accelerations leading to mechanical vibrations. Moreover, uncertainties are abundant in such systems due to model simplifications, the wear of the components of the robot and the variations of the environment. Furthermore, their coupled dynamics and actuation redundancy in some mechanisms give rise to complex and challenging control issues. Consequently, the developed control schemes should take into account all the previously mentioned issues and challenges. The main goal of this thesis lies in the proposal of new adaptive control schemes for PKMs while considering their characteristics and particularities in order to improve their tracking capabilities. Moreover, the developed control strategies should be first validated through numerical simulations, then through real-time experiments on available PKMs. Within this context, three main contributions are proposed in this thesis. First, a new class of adaptive controllers with nonlinear time-varying feedback gains is proposed. The second contribution lies in an adaptive-based extended version of RISE robust feedback control strategy. For the third contribution, the recently developed L1 adaptive control strategy is applied for the first time on a PKM, followed by two novel model-based extensions. Numerical simulations as well as real-time experiments on various PKMs prototypes are provided and discussed. All the proposed controllers are validated for different operating conditions in order to show their relevance and efficiency.

No description available.

L'objectif principal de ce travail est de proposer des approches de commande performantes et robustes aux incertitudes pour les robots parallèles de type Delta, qui sont conçus pour effectuer des tâches industriels importantes et exigeantes comme l'emballage en agroalimentaire, la découpe laser, etc. Les difficultés les plus importantes pour garantir une bonne performance de suivi de trajectoires de ces manipulateurs pour les hautes accélérations avec la meilleure précision possible, tout en conservant de telle performance indépendamment des conditions d'opération (par exemple avec différentes conditions de charge, différentes trajectoires, etc.) sont leur actionnement couplé, l'augmentation de leurs dynamiques non-linéaires et le problème de vibrations mécaniques avec l'augmentation des accélérations envisagées, la présence d'incertitudes sur le modèle/environnement et la redondance d'actionnement si elle existe. Dans cette thèse, différentes approches de commande et observateurs d'état ont été proposés et implémentés expérimentalement sur deux robots de type Delta, à savoir le Par2 (non-redondant) et le R4 (à redondance d'actionnement). Pour le premier, une commande non linéaire/adaptative à mode Dual a été proposée en espace articulaire, synthétisé avec trois différents observateurs d'état pour la estimation des vitesses articulaires: un observateur lead-lag, un observateur Alpha-bêta-gamma et un observateur à grand gain. Pour le robot R4, un commande à feedforward en espace-dual avec a été proposée pour la compensation de sa dynamique (avec laquelle une aaccélération maximale de 100G a été atteinte), puis un contrôleur adaptatif dans l'espace-dual a été proposé afin de garantir une estimation et mise à jours automatique des paramètres du système en temps réel, garantissant ainsi sa bonne performance indépendamment du scénario expérimental. L'analyse de stabilité du robot Par2 bouclé avec la commande adaptative à Mode Dual et du robot R4 commandé avec le contrôleur adaptatif dans l'espace-dual sont fournies, des simulations ont été effectuées et les résultats expérimentaux confirment la bonne performance des approches de commande proposées. / The main objective of this work is to propose control strategies performant and robust towards uncertainties for Delta-like parallel robots, which are designed to perform important and demanding industrial tasks, such as packaging, laser cutting, etc. The most important difficulties to guarantee the good tracking performance of these manipulators for very high accelerations with the best possible precision, while maintaining such performance independently of the operational case (e.g. with different load conditions, different trajectories, etc.) are their coupled actuation, the increase of their high nonlinear dynamics and the problem of mechanical vibrations with the increase of the involved accelerations, the presence of uncertainties in the model/environment and the redundant actuation when applicable. In this thesis, different control schemes and state observers were proposed and experimentally implemented on two Delta-like robots, namely the Par2 (non-redundant) and the R4 (redundantly actuated) parallel manipulators. For the former, a nonlinear/adaptive Dual Mode controller was proposed in the joint space, complied with three different state observers for the estimation of joint velocities: a Lead-lag based observer, an Alpha-beta-gamma observer and the High-gain observer. For the latter, firstly a dual-space feedforward controller was proposed for the compensation of its dynamics (with which a maximum of 100G of acceleration was reached), then a dual-space adaptive controller was proposed in order to automatically estimate the parameters of the system in real-time, thus guaranteeing its good performance independently of the experimental scenario. The stability analysis of Par2 robot under the control of the Dual Mode controller and the R4 robot under the control of the dual-space adaptive controller are provided, simulations were performed and the experimental results confirm the good performance of the proposed control schemes.