Stratégie de commande distribuée pour les manipulateurs rigides et flexibles assurant la stabilité des erreurs de suivi de trajectoires

Cette thèse de doctorat propose et valide expérimentalement une nouvelle stratégie de commande distribuée pour les manipulateurs rigides et flexibles assurant le suivi de trajectoires dans l’espace articulaire et cartésien. Cette stratégie est développée, dans un premier temps, pour les manipulateurs rigides. Ensuite, elle est modifiée pour prendre en compte la flexibilité des bras au niveau des manipulateurs flexibles. Dans le cas des manipulateurs rigides, cette stratégie est utilisée pour assurer un bon suivi de trajectoires dans l’espace de travail. Dans le cas où les paramètres du système sont parfaitement connus, une stratégie de commande distribuée est utilisée. Cette stratégie de commande décompose, dans un premier temps, la dynamique du manipulateur en plusieurs sous-systèmes non linéaires interconnectés. Chaque sous-système représente une articulation. Ensuite, la commande distribuée consiste à contrôler le manipulateur en commençant par la dernière articulation (sous-système) toute en supposant que le reste des articulations est stable. La même procédure est utilisée au rebours jusqu’à la première articulation. Dans le cas où les paramètres du système ne sont pas connus, une commande adaptative est développée. Dans ce contexte, la commande distribuée et adaptative peut être interprétée comme étant une commande hiérarchique. En effet, les paramètres inconnus, existant dans l’équation de mouvement du dernier sous-système, sont tout d’abord estimés et la loi de commande est ainsi déduite en fonction de ces paramètres. Puis, passant à l’avant-dernier sous-système, la loi de commande est développée en fonction de leurs propres paramètres estimés, existant dans l’équation de mouvement de l’avant-dernière articulation, et les paramètres estimés du sous-système de niveau supérieur. La même stratégie est utilisée à contresens jusqu’au premier sous-système. L’approche de Lyapunov est utilisée pour prouver la stabilité globale des erreurs de suivi. Les deux lois de commande sont validées expérimentalement sur un manipulateur rigide à 7 ddl et elles montrent un bon suivi dans l’espace articulaire et cartésien. Dans le cas des manipulateurs flexibles, cette stratégie est modifiée et étendue pour assurer un bon suivi de trajectoires dans l’espace articulaire et, en même temps, minimiser les vibrations au niveau des bras flexibles. Donc, en plus de l’objectif de suivi de trajectoire utilisée dans le cas des manipulateurs flexibles, la stratégie de commande doit assurer la déformation bornée et minimiser les vibrations des bras flexibles. Au contraire des manipulateurs rigide, les manipulateurs flexibles sont des systèmes sous-actionnés, c’est-à-dire ils possèdent plus de degrés de liberté que d’entrées de commande. Dans ce cas, chaque sous-système est composé d’une articulation et le bras flexible associé. Dans le cas où les paramètres du manipulateur sont parfaitement connus, une commande distribuée est développée pour assurer la stabilité des erreurs de suivi dans l’espace articulaire et réduire les vibrations des bras flexibles. Cette stratégie consiste à commander et stabiliser la dernière articulation ainsi que le dernier bras flexible en supposant que le reste des sous-systèmes sont stables. Puis, passons aux contrôle et stabilité de l’avant-dernier sous–système de la même façon. Cette démarche est suivie, au rebours, jusqu'au premier sous-système. Sa version adaptative, dite « hiérarchique », est également développée. La stabilité globale est prouvée en utilisant l’approche de Lyapunov. La validation expérimentale des deux lois de commande sur un manipulateur flexible à 2 ddl montre un bon suivi de trajectoires dans l’espace articulaire et des vibrations minimales au niveau des bras flexibles. Dans le cas de suivi de trajectoires dans l’espace de travail des manipulateurs flexibles, la cinématique inverse, utilisée pour les manipulateurs rigides, n’est plus suffisante pour transformer les trajectoires désirées de l’espace de travail vers l’espace articulaire. En plus d’une relation cinématique, il existe une relation dynamique entre l’espace de travail et articulaire. Pour résoudre ce problème, un espace intermédiaire, nommé « virtuel » et la méthode quasi-statique sont utilisés. En effet, la cinématique inverse est utilisée pour transformer la trajectoire désirée de l’espace de travail vers l’espace virtuel tandis que l'approche quasi-statique est utilisée pour le passage de l'espace virtuel à l'espace articulaire. Lors du contrôle direct de l’extrémité, les manipulateurs flexibles deviennent des systèmes à non minimum de phase et la dynamique interne n'est plus bornée. Pour surmonter ce problème, la technique de la redéfinition de sortie est utilisée pour sélectionner une sortie la plus proche possible de l'extrémité assurant une dynamique interne bornée. Cette sortie est composée de la position angulaire plus une valeur pondérée de la déformation de l’extrémité du bras flexible. Une étude de stabilité de la dynamique interne (ou dynamique des zéros) en utilisant la passivité est utilisée pour déterminer la valeur critique du paramètre caractérisant cette sortie paramétrisée. Deux lois de commande sont développées pour un robot à deux bras flexibles. La première loi de commande basée sur l’approche de linéarisation par retour d’état assure juste la stabilité locale des erreurs de suivi. La deuxième loi de commande constitue une généralisation pour assurer la stabilité globale de la dynamique des erreurs de suivi. Ces deux algorithmes sont testés sur un robot à deux bras flexibles et montrent un bon suivi de trajectoires dans l’espace de travail

Nonlinear control of multiple mobile manipulator robots transporting a rigid object in coordination

This doctoral thesis proposes and validates experimentally nonlinear control strategies for a group of mobile manipulator robots transporting a rigid object in coordination. This developed approach ensures trajectory tracking in Cartesian space in the presence of parameter uncertainty and undesirable disturbances. The objective of the creation of robots in the early sixties was to relieve man of certain hard jobs such as: handling a heavy object, and repetitive tasks which are often tiring or even sometimes infeasible manually. Following this situation, several types of manipulator robots were created. Naturally, the need for robots having both locomotion and manipulation capabilities has led to the creation of the mobile manipulators. Typical examples of mobile manipulators, more or less automated, are the cranes mounted on trucks , the satellite arms, the deep-sea exploration submarines, or extra-planetary exploration vehicles. Some operations requiring the handling of a heavy object are difficult to achieve by a single mobile manipulator. These operations require a coordination of several mobile manipulators to move or transport a heavy object in common. However, this complicates the robotic system as its control design complexity increases greatly. The problem of controlling the mechanical system forming a closed kinematic chain mechanism lies in the fact that it imposes a set of kinematic constraints on the coordination of the position and velocity of the mobile manipulator. Therefore, there is a reduction in the degrees of freedom for the entire system. Further, the internal forces of the object produced by all mobile manipulators should be controlled. This thesis work was focused on developing a consistent control technique for a group of mobile manipulator robots executing a task in coordination. Different nonlinear controllers were simulated and experimentally applied to multiple mobile manipulator system transporting a rigid object in coordination. To achieve all objectives of this thesis, as a first step, an experimental platform was developed and mounted in the laboratory of GREPCI-ETS to implement and validate the different designed control laws. In the second step, several adaptive coordinated motion/force tracking control laws were applied, ensuring that the desired trajectory can excellently tracked under uncertainties parameters and disturbances

Advances in Robot Kinematics : Proceedings of the 15th international conference on Advances in Robot Kinematics

International audienceThe motion of mechanisms, kinematics, is one of the most fundamental aspect of robot design, analysis and control but is also relevant to other scientific domains such as biome- chanics, molecular biology, . . . . The series of books on Advances in Robot Kinematics (ARK) report the latest achievement in this field. ARK has a long history as the first book was published in 1991 and since then new issues have been published every 2 years. Each book is the follow-up of a single-track symposium in which the participants exchange their results and opinions in a meeting that bring together the best of world’s researchers and scientists together with young students. Since 1992 the ARK symposia have come under the patronage of the International Federation for the Promotion of Machine Science-IFToMM.This book is the 13th in the series and is the result of peer-review process intended to select the newest and most original achievements in this field. For the first time the articles of this symposium will be published in a green open-access archive to favor free dissemination of the results. However the book will also be o↵ered as a on-demand printed book.The papers proposed in this book show that robot kinematics is an exciting domain with an immense number of research challenges that go well beyond the field of robotics.The last symposium related with this book was organized by the French National Re- search Institute in Computer Science and Control Theory (INRIA) in Grasse, France

Advances in Mechanical Systems Dynamics 2020

The fundamentals of mechanical system dynamics were established before the beginning of the industrial era. The 18th century was a very important time for science and was characterized by the development of classical mechanics. This development progressed in the 19th century, and new, important applications related to industrialization were found and studied. The development of computers in the 20th century revolutionized mechanical system dynamics owing to the development of numerical simulation. We are now in the presence of the fourth industrial revolution. Mechanical systems are increasingly integrated with electrical, fluidic, and electronic systems, and the industrial environment has become characterized by the cyber-physical systems of industry 4.0. Within this framework, the status-of-the-art has become represented by integrated mechanical systems and supported by accurate dynamic models able to predict their dynamic behavior. Therefore, mechanical systems dynamics will play a central role in forthcoming years. This Special Issue aims to disseminate the latest research findings and ideas in the field of mechanical systems dynamics, with particular emphasis on novel trends and applications

Annals of Scientific Society for Assembly, Handling and Industrial Robotics 2021

This Open Access proceedings presents a good overview of the current research landscape of assembly, handling and industrial robotics. The objective of MHI Colloquium is the successful networking at both academic and management level. Thereby, the colloquium focuses an academic exchange at a high level in order to distribute the obtained research results, to determine synergy effects and trends, to connect the actors in person and in conclusion, to strengthen the research field as well as the MHI community. In addition, there is the possibility to become acquatined with the organizing institute. Primary audience is formed by members of the scientific society for assembly, handling and industrial robotics (WGMHI)

Annals of Scientific Society for Assembly, Handling and Industrial Robotics 2021

This Open Access proceedings presents a good overview of the current research landscape of assembly, handling and industrial robotics. The objective of MHI Colloquium is the successful networking at both academic and management level. Thereby, the colloquium focuses an academic exchange at a high level in order to distribute the obtained research results, to determine synergy effects and trends, to connect the actors in person and in conclusion, to strengthen the research field as well as the MHI community. In addition, there is the possibility to become acquatined with the organizing institute. Primary audience is formed by members of the scientific society for assembly, handling and industrial robotics (WGMHI)

Humanoid Robot Soccer Locomotion and Kick Dynamics: Open Loop Walking, Kicking and Morphing into Special Motions on the Nao Robot

Striker speed and accuracy in the RoboCup (SPL) international robot soccer league is becoming increasingly important as the level of play rises. Competition around the ball is now decided in a matter of seconds. Therefore, eliminating any wasted actions or motions is crucial when attempting to kick the ball. It is common to see a discontinuity between walking and kicking where a robot will return to an initial pose in preparation for the kick action. In this thesis we explore the removal of this behaviour by developing a transition gait that morphs the walk directly into the kick back swing pose. The solution presented here is targeted towards the use of the Aldebaran walk for the Nao robot. The solution we develop involves the design of a central pattern generator to allow for controlled steps with realtime accuracy, and a phase locked loop method to synchronise with the Aldebaran walk so that precise step length control can be activated when required. An open loop trajectory mapping approach is taken to the walk that is stabilized statically through the use of a phase varying joint holding torque technique. We also examine the basic princples of open loop walking, focussing on the commonly overlooked frontal plane motion. The act of kicking itself is explored both analytically and empirically, and solutions are provided that are versatile and powerful. Included as an appendix, the broader matter of striker behaviour (process of goal scoring) is reviewed and we present a velocity control algorithm that is very accurate and efficient in terms of speed of execution

Robust execution of bipedal walking tasks from biomechanical principles

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.Includes bibliographical references (p. 348-352).Effective use of robots in unstructured environments requires that they have sufficient autonomy and agility to execute task-level commands successfully. A challenging example of such a robot is a bipedal walking machine. Such a robot should be able to walk to a particular location within a particular time, while observing foot placement constraints, and avoiding a fall, if this is physically possible. Although stable walking machines have been built, the problem of task-level control, where the tasks have stringent state-space and temporal requirements, and where significant disturbances may occur, has not been studied extensively. This thesis addresses this problem through three objectives. The first is to devise a plan specification where task requirements are expressed in a qualitative form that provides for execution flexibility. The second is to develop a task-level executive that accepts such a plan, and outputs a sequence of control actions that result in successful plan execution. The third is to provide this executive with disturbance handling ability. Development of such an executive is challenging because the biped is highly nonlinear and has limited actuation due to its limited base of support. We address these challenges with three key innovations.(cont.) To address the nonlinearity, we develop a dynamic virtual model controller to linearize the biped, and thus, provide an abstracted biped that is easier to control. The controller is model-based, but uses a sliding control technique to compensate for model inaccuracy. To address the under-actuation, our system generates flow tubes, which define valid operating regions in the abstracted biped. The flow tubes represent sets of state trajectories that take into account dynamic limitations due to under-actuation, and also satisfy plan requirements. The executive keeps trajectories in the flow tubes by adjusting a small number of control parameters for key state variables in the abstracted biped, such as center of mass. Additionally, our system uses a novel strategy that employs angular momentum to enhance translational controllability of the system's center of mass. We evaluate our approach using a high-fidelity biped simulation. Tests include walking with foot-placement constraints, kicking a soccer ball, and disturbance recovery.by Andreas G. Hofmann.Ph.D

Annals of Scientific Society for Assembly, Handling and Industrial Robotics 2021

This Open Access proceedings presents a good overview of the current research landscape of assembly, handling and industrial robotics. The objective of MHI Colloquium is the successful networking at both academic and management level. Thereby, the colloquium focuses an academic exchange at a high level in order to distribute the obtained research results, to determine synergy effects and trends, to connect the actors in person and in conclusion, to strengthen the research field as well as the MHI community. In addition, there is the possibility to become acquatined with the organizing institute. Primary audience is formed by members of the scientific society for assembly, handling and industrial robotics (WGMHI)