Th. doct.-ing.--Nancy, I.N.P.L., 1980. / Rés.

Reproduction de : Thèse de doctorat : Sciences:génie mécanique : Reims : 2004. / Titre provenant de l'écran titre. Bibliogr. f. 121-125.

Les systèmes simples et les systèmes plus évolués tels que les robots aident l’être humain à accomplir plusieurs tâches depuis fort longtemps. Dans certains cas, le système en question remplace carrément l’humain alors que dans d’autres, le système agit en coopération avec celui-ci. Dans le dernier cas, le système représente plus un outil servant à augmenter les performances ou bien à éviter des tâches ingrates. L’avantage principal de cette augmentation humaine est de laisser à l’opérateur une certaine latitude dans le processus décisionnel de la tâche. Les forces propres aux humains et aux robots sont donc combinées afin d’obtenir une synergie, c’est-à-dire d’obtenir un meilleur système que la somme de ses composantes. Cependant, accomplir des tâches de coopération complexes de manière intuitives représente un défi de taille. Alors qu’auparavant les robots étaient isolés et donc conçus et programmés en conséquence, la nouvelle génération de robots doit être capable de comprendre son environnement et les intentions de l’humain, et d’y répondre adéquatement et de manière sécuritaire, intuitive, conviviale et ergonomique. Ceci apporte de nombreux débouchés dans différents domaines tels que la manutention, l’assemblage manufacturier, la réadaptation physique, la chirurgie, l’apprentissage via des simulations haptiques, l’aide aux personnes handicapées et bien d’autres. Cette thèse comporte trois parties. La première traite de la commande des robots d’interaction physique. L’approche pour parvenir à une commande intuitive, les bonnes pratiques, un algorithme d’interaction s’adaptant aux intentions de l’humain et l’adaptation d’une commande par couple pré-calculé à l’interaction humain-robot sont présentés. La deuxième partie traite de systèmes mains sur la charge qui sont plus intuitifs à utiliser pour l’opérateur. Le développement de ces systèmes comprend des innovations mécaniques et de commande avancées. La troisième partie traite finalement d’éléments de sécurité. Elle présente d’abord le développement d’un algorithme d’observation et de contrôle des vibrations et ensuite le développement d’un capteur détectant à distance la proximité humaine. Cette thèse se propose d’apporter plusieurs contributions, tant dans un esprit scientifique que pour des applications industrielles requérant des réponses immédiates. / For a long time, simple and advanced systems such as robots have been helping humans to accomplish several tasks. In some cases, the system simply replaces the operator while in other cases, the system cooperates with him/her. In the latter case, the system is more a tool used to increase performance or to avoid unpleasant tasks. The principal advantage of this human augmentation is to leave a certain latitude to the operator in the task decision process. Specific strengths of humans and robots are then combined to obtain a synergy, that is obtaining a more complete system than the sum of its parts. However, achieving complex tasks in a way that is intuitive to the human represents a huge challenge. While robots were previously segregated from humans and then designed and programmed accordingly, the new generation of robots must be able to perceive their environment and the human intentions and to respond to them safely, adequately, intuitively and ergonomically. This leads to several opportunities in a wide range of fields such as materials handling, assembly, physical rehabilitation, surgery, learning through haptic simulations, help to disabled people and others. This thesis comprises three parts. The first one deals with the control of physical interaction robots. The approach to an intuitive control, good practices, an interaction algorithm adapting to human intentions and the adaptation of a computed-torque control scheme for human-robot interaction are presented. The second part presents hands on payload systems which are more intuitive to use for the operator. These system developments include mechanical and advanced control innovations. The third part introduces safety features. First, the development of a vibration observer/controller algorithm is presented and then the development of a sensor detecting human proximity is reported. This thesis attempts to provide contributions, in a scientific spirit as much as for industrial applications requiring immediate solutions.

The aim of the thesis is to propose active damping as a potential control strategy for chatter instability in machine tools.<p>The regenerative process theory explains chatter as a closed loop interaction between the structural dynamics and the cutting process. This is considered to be the most dominant reason behind machine tool chatter although other instability causing mechanisms exist.<p>The stability lobe diagram provides a quantitative idea of the limits of stable machining in terms of two physical parameters: the width of contact between tool and the workpiece, called the width of cut and the speed of rotation of the spindle. It is found that the minimum value of the stability limit is proportional to the structural damping ratio for turning operations. This important finding provides the motivation of influencing the structural dynamics by active damping to enhance stability limits of a machining operation.<p>A direct implementation of active damping in an industrial environment may be difficult. So an intermediate step of testing the strategy in a laboratory setup, without conducting real cutting is proposed. Two mechatronic "Hardware in the Loop" simulators for chatter in turning and milling are presented, which simulate regenerative chatter experimentally without conducting real cutting tests. A simple cantilever beam, representing the MDOF dynamics of<p>the machine tool structure constitutes the basic hardware part and the cutting process is simulated in real time on a DSP board. The values of the cutting parameters such as spindle speed and the axial width of cut can be changed on the DSP board and the closed loop interaction between the structure and the cutting process can be led to instability.<p><p>The demonstrators are then used as test beds to investigate the efficiency of active damping, as a potential chatter stabilization strategy. Active damping is easy to implement, robust and does not require a very detailed model of the structure for proper functioning, provided a collocated sensor and actuator configuration is followed. The idea of active damping is currently being implemented in the industry in various metal cutting machines as part of the European Union funded SMARTOOL project (www.smartool.org), intended to propose smart chatter control technologies in machining operations. / Doctorat en sciences appliquées / info:eu-repo/semantics/nonPublished

In this work, we investigate the active vibration isolation and damping of sensitive equipment. Several single-axis isolation techniques are analyzed and tested. A comparison between the sky-hook damper, integral force feedback, inertial velocity feedback and LagLead control techniques is conducted using several practical examples.<p><p>The study of single-axis systems has been developed and used to build a six-axis isolator. A six degrees of freedom active isolator based on Stewart platform has been designed manufactured and tested for the purpose of active vibration isolation of sensitive payloads in space applications. This six-axis hexapod is designed according to the cubic configuration; it consists of two triangular parallel plates connected to each other by six active legs orthogonal to each other; each leg consists of a voice coil actuator, a force sensor and two flexible joints. Two different control techniques have been tested to control this isolator :integral force feedback and Lag-Lead compensator, the two techniques are based on force feedback and are applied in a decentralized manner. A micro-gravity parabolic flight test has been clone to test the isolator in micro-gravity environment.<p><p>ln the context of this research, another hexapod has been produced ;a generic active damping and precision painting interface based on Stewart platform. This hexapod consists of two parallel plates connected to each other by six active legs configured according to the cubic architecture. Each leg consists of an amplified piezoelectric actuator, a force sensor and two flexible joints. This Stewart platform is addressed to space applications where it aims at controlling the vibrations of space structures while connecting them rigidly. The control technique used here is the decentralized integral force feedback.<p><p> / Doctorat en sciences appliquées / info:eu-repo/semantics/nonPublished