During the latest ten years, development in the industry of machine tools has been growing rapidly in our country. Since industry automation is highly demanded, the study about CNC is therefore extensively proceeded. Owing to request for higher quality, the machine tool must achieve the high speed and high precision. There are three factors in precise motion control : the accuracy of reference command, the design of servo control structure, and machine structure. However the part of machine structure attains to maturity. The design of the control system need to include good motion control and correct reference command. NURBS can represent analytic curves and free-form curves accurately and easily. Cross-coupled control is able to adjust the dynamic system of each axis to reduce the contour errors. It is expected to improve control performance in terms of contour errors by combine NURBS reference command and the cross-coupled control framework. Keywords¡Gmachine tool, NURBS, cross-coupled control

As the electronic products are gotten smaller and the quantity of output is to be requested, the trend of the needs for speed and accuracy is more precise. Therefore, upgrading the speed and the accuracy of contour error on tracking control has become an important point. This research is focus on the improvement of tracking error and contour error. In tracking error, we propose that the compensation of friction disturbance is by building friction model. And then adaptive robust controller is used to eliminate other disturbance. Finally, velocity feedforward controller is used to improve system dynamic response and to remove the effect of time delay. The combination of such controllers can improve tracking error directly and contour error indirectly. In contour error, we use cross-coupled controller to coordinate the motors and to reform contour error. On the association of such controllers, we propose the design method of cross-coupled controller, to replace the traditional way of try-and-error, and improving contour error again. Finally, the above improving strategies are verified by the simulation and experimental results.

Translational and rotational motion are coupled for spacecraft performing formation flying missions. This motion is coupled because orbital control is dependent on the spacecraft attitude for vectored thrust. Formation flying spacecraft have a limited mass and volume for propulsion systems. We want to maximize the efficiency of the spacecraft, which leads to minimizing the error introduced by thrusting in the wrong direction. This thrust direction error leads to the need for a coupled attitude and orbital control strategy. In this thesis a coupled control system is developed using a nonlinear Lyapunov attitude controller and a nonlinear Lyapunov-based orbital controller. A nonlinear Lyapunov attitude controller is presented for a spacecraft with three-axis momentum wheel control. The nonlinear Lyapunov-based orbital controller is combined with a mean motion control strategy to provide a globally asymptotically stable controller. The attitude and orbit control laws are verified separately using numerical simulation, and then are integrated into a coupled control strategy. The coupled system simulations verify that the coupled control strategy is able to correct for an initial relative position error between two spacecraft. / Master of Science

As the electronic products are getting more and more small, the trend of the needs for speed and accuracy is more precise. Therefore, upgrading the speed and the accuracy of contour error on tracking control has become an important point. This research is focus on the improving of contour error and terminus error. In the contour error, we design the acceleration /deceleration profile based on digital FIR filter. And then remodel the compensatory method of cross-coupled controller, making the design of controller parameter easier, and getting better efficiency. And further, we get the time-variable gain by curve of contour error, making the accuracy better. In terminus error, according to two-step control, we switch the controller in deceleration region, not only directly improving the terminus error, but also improving the contour error. Finally, the above improved strategies are verified by the simulation and experimental results.

Les travaux de cette thèse portent sur la navigation des véhicules autonomes, notamment la planification de trajectoires et le contrôle du véhicule. En premier lieu, un modèle véhicule plan est développé en utilisant une technique de modélisation qui assimile le véhicule à un robot constitué de plusieurs corps articulés. La description géométrique du véhicule est basée sur la convention de Denavit-Hartenberg modifiée. Le modèle dynamique du véhicule est ensuite calculé en utilisant la méthode récursive de Newton-Euler, qui est souvent utilisée dans le domaine de robotique. La validation du modèle a été conduite sur le simulateur Scaner-Studio développé par Oktal pour les applications automobiles. Le modèle du véhicule développé est ensuite utilisé pour la synthèse de lois de commande couplées pour les dynamiques longitudinale et latérale du véhicule. Deux correcteurs sont proposés dans ce travail : le premier est basé sur les techniques de commande par Lyapunov, le second utilise une approche ”Immersion et Invariance”. Ces deux contrôleurs ont pour objectifs de suivre une trajectoire de référence donnée avec un profil de vitesse désirée, tout en tenant compte du couplage existant entre les dynamiques longitudinale et latérale du véhicule. En effet, le contrôle couplé est nécessaire pour garantir la sécurité du véhicule autonome surtout lors de l’exécution des manœuvres couplées comme les manœuvres de changement de voie, les manœuvres d’évitement d’obstacles et les manœuvres exécutées dans les situations de conduite critiques. Les contrôleurs développés ont été validés en simulation sous Matlab/Simulink en utilisant des données expérimentales. Par la suite, ces contrôleurs ont été validés expérimentalement en utilisant le véhicule démonstrateur robotisé (Renault-Zoé) du laboratoire Heudiasyc financé par l’Equipex Robotex. En ce qui concerne la planification de trajectoires, une méthode de planification basée sur la méthode des tentacules sous forme de clothoides a été développée. En outre, une méthode de planification de manœuvres qui s’intéresse essentiellement à la manœuvre de dépassement a été mise en place, afin d’améliorer et de compléter la méthode locale des tentacules. Le planificateur local et le planificateur de manœuvres ont été ensuite combinés pour établir une stratégie de navigation complète. Cette stratégie a été validée par la suite sous Matlab/Simulink en utilisant le modèle de véhicule développé et le contrôleur basé sur Lyapunov. / In this thesis, the trajectory planning and the control of autonomous vehicles are addressed. As a first step, a multi-body modeling technique is used to develop a four wheeled vehicle planar model. This technique considers the vehicle as a robot consisting of articulated bodies. The geometric description of the vehicle system is derived using the modified Denavit Hartenberg parameterization and then the dynamic model of the vehicle is computed by applying a recursive method used in robotics, namely Newton-Euler based Algorithm. The validation of the developed vehicle model was then conducted using an automotive simulator developed by Oktal, the Scaner-Studio simulator. The developed vehicle model is then used to derive coupled control laws for the lateral and the longitudinal vehicle dynamics. Two coupled controllers are proposed in this thesis: In the first controller, the control is designed using Lyapunov control techniques while in the second one an Immersion and Invariance approach is used. Both of the controllers aim to ensure a robust tracking of the reference trajectory and the desired speed while taking into account the strong coupling between the lateral and the longitudinal vehicle dynamics. In fact, the coupled controller is a key step for the vehicle safety handling, especially in coupled maneuvers such as lane-change maneuvers, obstacle avoidance maneuvers and combined maneuvers in critical driving situations. The developed controllers were validated in simulation under Matlab/Simulink using experimental data. Subsequently, an experimental validation of the proposed controllers was conducted using a robotized vehicle (Renault-ZOE) present in the Heudiasyc laboratory within the Equipex Robotex project. Concerning the trajectory planning, a local planning method based on the clothoid tentacles method is developed. Moreover, a maneuver planning strategy focusing on the overtaking maneuver is developed to improve and complete the local planning approach. The local and the maneuver planners are then combined in order to establish a complete navigation strategy. This strategy is then validated using the developed robotics vehicle model and the Lyapunov based controller under Matlab/Simulink.