Hydraulic systems are widely applied in industry for position or force control. However, due to hydraulic system nonlinearities, it is difficult to achieve a precise model valid over a large range of frequencies and movements. The work in this dissertation focuses on a high performance hydraulic test bench which involves three main hydraulic components, i.e. two high performance servovalves, a double rod actuator, and a specific intermediate block connecting the servovalves and actuator. This rig has been designed for testing aerospace or automotive components in real conditions (e.g. wear and ageing effects). The main objectives of this dissertation are first the development of a virtual prototype based on a precise model which is derived from the physical principles and experimental works, and then second the synthesis of several nonlinear control laws of this actuation system in a large operating range with a good robustness to the perturbations. The proposed model based on Bond Graph shows a very good agreement with experimental results not only at low frequencies, but also at high frequencies. Moreover, its performances are improved at high frequencies by introducing the dynamic effects due to the intermediate block. Besides, multivariable and monovariable control strategies, based on respectively the backstepping and the model-free method, are developed and implemented on the test bench. All the control strategies proposed have been validated by simulations and experiments. Results show they lead to better tracking precision and robustness performance compared to the conventional control techniques.

Pas de résumé / No abstract

Les systèmes électro-hydrauliques sont largement utilisés dans l’industrie pour des contrôles de position ou d’effort. Cependant, à cause des non-linéarités du système électro-hydraulique, il est difficile d’établir un modèle précis valable sur une large bande de fréquences et de grands mouvements. Le travail de cette thèse concerne un banc d’essai électro-hydraulique qui comporte trois composants hydrauliques principaux, à savoir deux servovalves haute performance, un vérin à double tige, et une embase spécifique qui relie les servovalves et le vérin. Ce banc d’essai a été conçu pour tester des composants aéronautique et automobile dans des conditions réelles (par exemple, tests d'usure ou de vieillissement). Le premier objectif principal de cette thèse concerne la mise en œuvre d’un prototype virtuel basé sur un modèle précis issu de considérations physiques et d'un travail expérimental afin d'identifier les paramètres et de valider le réalisme du prototype virtuel. Le deuxième objectif est d'élaborer des lois de commande non-linéaires sophistiquées avec une large plage de fonctionnement et une bonne robustesse aux perturbations. Le modèle proposé basé sur le Bond Graph montre une très bonne adéquation entre les résultats de simulation et les résultats expérimentaux non seulement en basses fréquences, mais également en fréquences élevées. En particulier, les performances en hautes fréquences sont nettement améliorées par l'introduction des effets dynamiques liés à l’embase. En outre, des lois de commande, respectivement basées sur le backstepping et sur la commande sans modèle, ont été élaborées et mises en œuvre sur le banc d’essai. Toutes les lois de commande proposées ont été validées à la fois en simulation et expérimentalement. Les résultats montrent qu’ils conduisent à de meilleures performances en suivi de position et en robustesse par rapport aux lois de commande classiques. / Hydraulic systems are widely applied in industry for position or force control. However, due to hydraulic system nonlinearities, it is difficult to achieve a precise model valid over a large range of frequencies and movements. The work in this dissertation focuses on a high performance hydraulic test bench which involves three main hydraulic components, i.e. two high performance servovalves, a double rod actuator, and a specific intermediate block connecting the servovalves and actuator. This rig has been designed for testing aerospace or automotive components in real conditions (e.g. wear and ageing effects). The main objectives of this dissertation are first the development of a virtual prototype based on a precise model which is derived from the physical principles and experimental works, and then second the synthesis of several nonlinear control laws of this actuation system in a large operating range with a good robustness to the perturbations. The proposed model based on Bond Graph shows a very good agreement with experimental results not only at low frequencies, but also at high frequencies. Moreover, its performances are improved at high frequencies by introducing the dynamic effects due to the intermediate block. Besides, multivariable and monovariable control strategies, based on respectively the backstepping and the model-free method, are developed and implemented on the test bench. All the control strategies proposed have been validated by simulations and experiments. Results show they lead to better tracking precision and robustness performance compared to the conventional control techniques.