Search

In this paper an approach for controlling overhead cranes by avoiding oscillations is proposed and experimentally tested. In particular, a dynamic inversion technique is applied to the overhead crane model to design suitable (position or velocity) set-point and torque feedforward signals. The inversion approach is further simplified in order to make the proposed methodology more industrial-oriented. Experimental results, obtained by using a scaled overhead crane built by using only off-the-shelf components, show the effectiveness of the proposed methodology.

In this paper, we propose a new method for the improvement of set-point-following performances of industrial controllers. Basically, this new approach consists of substituting the standard step signal to be applied to the closed-loop system (in which the controller has been previously selected) with a command input function that is determined by means of a dynamic inversion procedure. This procedure is based on a fast algorithm, and it is therefore suitable for application in an industrial context, where the ease of implementation is of major concern. Simulation results show the effectiveness of the technique.

Flight-Critical Systems such as Electromechanical Actuators driven by Engine Control Units (ECU) or Flight Control Units (FCU) are designed and developed regarding drastic safety requirements. In this study, an actuator control and monitoring ECU architecture based on analytic redundancy is proposed. In case of fault occurrences, material redundancies in avionic equipment allow certaincritical systems to reconfigure or to switch into a safe mode. However, material redundancies increase aircraft equipment size, weight and power (SWaP). Monitoring based on dynamical models is an interesting way to further enhance safetyand availability without increasing the number of redundant items. Model-base dfault detection and isolation (FDI) methods [58, 26, 47] such as observers and parity space are recalled in this study. The properties of differential flatness for nonlinear systems [80, 41, 73] and endogenous feedback linearisation are used with nonlinear diagnosis models. Linear and nonlinear observers are then compared with an application on hybrid stepper motor (HSM). A testing bench was specially designed to observe in real-time the behaviour of the diagnosis models when faults occur on the stator windings of a HSM., Les systèmes critiques de vol tels que les actionneurs électromécaniques ainsi que les calculateurs de commande moteur (ECU) et de vol (FCU),sont conçus en tenant compte des contraintes aéronautiques sévères de sureté defonctionnement. Dans le cadre de cette étude, une architecture calculateur pourla commande et la surveillance d’actionneurs moteur et de surfaces de vol est proposée et à fait l’objet d’un brevet [13]. Pour garantir ces mesure de sureté, les ECU et FCU présentent des redondances matérielles multiples, mais engendrent une augmentation de l’encombrement, du poids et de l’énergie consommée. Pour ces raisons, les redondances à base de modèles dynamiques, présentent un atout majeur pour les calculateurs car elles permettent dans certains cas de maintenir les exigences d’intégrité et de disponibilité tout en réduisant le nombre de capteurs ou d’actionneurs. Un rappel sur les méthodes de diagnostic par générateurs de résidus et estimateurs d’états [58, 26, 47] est effectué dans cette étude. Les propriétés de platitude différentielle et la linéarisation par difféomorphisme et bouclage endogène [80, 41, 73] permettent d’utiliser des modèles linéaires équivalents avec les générateurs de résidus. Un banc d’essai a été conçu afin de valider les performances des algorithmes de diagnostic.

This paper focuses on a design method for feedback and feedforward fractional order control of electromechanical systems. The architecture combines a fractional order proportional-integral controller and a set-point filter. First, the open-loop frequency response is shaped to obtain robustness specifications and to approximate an optimal feedback system in the input-output tracking, at least in a specified bandwidth. Secondly, the set-point filter is designed by dynamic inversion to minimize the difference between the ideal synthesized command signal, that provides a smooth monotonic response, and the filter step response. Tests on the position/speed control of DC and permanent magnet synchronous motors show the effectiveness of the methodology in comparison with PI controller tuned by symmetrical optimum and coupled with a smoothing filter.

In this paper we propose a novel approach to design a set-point filter based on a dynamic inversion technique. First, a suitable command signal is designed in order to obtain a smooth monotonic output transition. Then, a set-point filter is determined based on the synthesized command signal. The filter is computed by minimizing the 2-norm difference between the command signal and the filter step response. The proposed approach is suitable for the design of two degree-of-freedom control systems because the set-point tracking performance is independent from the chosen feedback controller. Simulation results prove the effectiveness of the proposed methodology.

In the coming years, unmanned combat air vehicles will be designed to outperform most pilot-in-the-loop systems. The absence of a pilot onboard allows larger flight envelopes to be considered with, for example, higher load factors. From a control perspective, the above induces new needs for improved design methods to obtain robust controllers that will automatically adapt to extremely varying flight conditions. Based on the well-known concept of nonlinear dynamic inversion (NDI), the approach of this paper introduces an original and rather generic “robustification” framework, which leads to a multi-objective H∞ design problem. The latter is now easily solved by existing and efficient numerical tools based on nonsmooth optimization. The proposed design methodology is illustrated by a combat aircraft control problem., AerospaceLab Journal, Issue 8, December 2014; ISSN: 2107-6596

This paper is concerned with flight controller design of D-SEND#2. D-SEND is a project to demonstrate a low sonic boom aerodynamic design concept. In the #2 part of this project, an unpowered test vehicle is lifted to an altitude of 30km by a balloon from which it then separates. After the separation, the vehicle's on-board flight control computer selects a target Boom Measurement System (BMS) according to the separation point. The vehicle then autonomously flies to the selected BMS and establishes prescribed sonic boom measurement flight conditions. The design of the GNC system for D-SEND#2 project is exceptionally challenging since 1) there is no nominal trajectory, 2) there is only limited control available to meet various requirements, 3) the flight envelope is quite wide, and 4) the development time is short. Dynamic inversion method and time-scale separation technique are applied to deal with these problems, and a systematic controller design procedure is presented. The controller is designed with this procedure and evaluated through linear analysis and Monte-Carlo simulations which shows it has sufficient performance and safety margines. This controller design method is confirmed to be a practical method for UAVs., 形態: 図版あり, Physical characteristics: Original contains illustrations, 資料番号: DS1640080003

This paper describes the design of a manual flight controller, based upon nonlinear model-based control laws. These control laws include the previously developed concept of Pseudo Control Hedging (PCH). This PCH algorithm adapts the reference model for the system output in case of unachievable commands due to control input saturation. This control algorithm has been applied in the body angular rate control loops of a high fidelity simulation model of the VFW-614 ATTAS (Advanced Technologies Testing Aircraft System) laboratory aircraft, where its beneficial influence has been illustrated. Test flights have been performed with ATTAS to evaluate the flight control technique in a relevant environment.

The paper presents a new system for the automat control of the aircrafts- flight in lateral plane using the cinematic model and the dynamic inversion. Starting from the equations of the aircrafts- lateral movement, the authors use two axes systems and obtained a control law that cancels the lateral deviation of the flying objects from the runway line. This system makes the aircrafts- direction angle to follow the direction angle of the runway line. Simulations in Matlab/Simulink have been done for different aircraft-s initial points and direction angles. The inconvenience of this system is the long duration of the "transient regime". That is why this system can be used independently, but the results are not very good; thus, it can be a part (subsystem) of other systems. The main system that cancels the lateral deviation from the runway line is based on dynamic inversion and uses, as subsystem, the control system for the lateral movement using the cinematic model. Using complex Matlab/Simulink models, the authors obtained the time evolution of the direction angle and the time evolution of the aircraft lateral deviation with respect to the runway line, for different values of the initial direction angle and for different wind types. The system has a very good behavior for all initial direction angles and wind types., {"references":["M. Niculescu, \"Lateral Track control Law for Aerosonde UAV\". AIAA\nno. 2001-0016, pp. 1-11, 2001, 39th AIAA Aerospace Science Meeting\nand Exhibit, 8-11 January 2001, Reno.","Mc.L. Donald, Automatic Flight Control Systems. Prentice Hall\nPublisher, 1990, 593 pp.","V. Ricny, J. Mikulec, \"Measuring flying object velocity with CCD\nsensors\". IEEE Aerospace and Electronic Systems Magazine, vol.9,\nIssue 6, pp. 3-6, June 1994.","B. Gollomp, \"The angle of attack\". IEEE Instrumentation &\nMeasurement Magazine, vol.4, Issue 1, pp. 57-58, 2001.","M. Lungu, Sisteme de conducere a zborului. Sitech Publisher, 2008.","Mackunis, P.M. Patre, M.K. Kaise, W.E. Dixon, \"Asymptotic Tracking\nfor Aircraft via Robust and Adaptive Dynamic Inversion Methods\",\nIEEE Transactions on Control Systems and Technology, vol. 18, no.6,\n2010.","N.A. Denison, Automated Carrier Landing of an Unmanned Combat\nAerial Vehicle Using Dynamic Inversion, Master's thesis, June 2007.","H.B. Chen, S.G. Zhang, \"Robust dynamic inversion flight control law\ndesign\", 2nd International Symposion on Systems and Control in\nAerospace and Astronautics, Shenzhen, December 2008.","A.J. Calise, R.T. Rysdyk, \"Adaptive Model Inversion Flight Control for\nTiltrotor Aircraft\", AIAA Guidance, Navigation and Control, vol. 22, pp.\n402-407, 1999.\n[10] C. Huang, Q. Shao, P. Jin, Z. Zhu, P. Luoyang, \"Pitch Attitude\nController Design and Simulation for a Small Unmanned Aerial\nVehicle\". International Conference on Intelligent Human-Machine\nSystems and Cybernetics, IHMSC '09, Hangzhou, Zhejiang, 26-27 Aug.\n2009, pp. 58-61.\n[11] S. Santos, N. Oliveira, \"Test platform to pitch angle using hardware in\nloop\". 39th IEEE Frontiers in Education Conference, FIE '09, San\nAntonio, 18-21 Oct. 2009, pp. 1-5.\n[12] A.A. Pashilkar, N. Sundararajan, P.A. Saratchandran, \"Fault-Tolerant\nNeural Aided Controller for Aircraft Auto-Landing\". Aerospace Science\nand Technology, vol.10, Issue 1. 2006, pp. 49-61.\n[13] V. Kargin, Design of An Autonomous Landing Control Algorithm for A\nFixed Wing UAV. MS Thesys, Middle East Technical University,\nAnkara, Turkey, 2007."]}

This paper presents a flight control strategy based on nonlinear dynamic inversion. The approach presented, called incremental nonlinear dynamic inversion, uses properties of general mechanical systems and nonlinear dynamic inversion by feeding back angular accelerations. Theoretically, feedback of angular accelerations eliminates sensitivity to model mismatch, greatly increasing the robust performance of the system compared with conventional nonlinear dynamic inversion. However, angular accelerations are not readily available. Furthermore, it is shown that angular acceleration feedback is sensitive to sensor measurement time delays. Therefore, a linear predictive filter is proposed that predicts the angular accelerations, solving the time delay and angular acceleration availability problem. The predictive filter uses only references and measurements of angular rates. Hence, the proposed control method makes incremental nonlinear dynamic inversion practically available using conventional inertial measurement units.

A novel way to design a nonlinear feedforward controller is introduced. Contrary to input-output linearization and pseudo control hedging techniques, the new formulation proposed is based on the states of the reference system instead on the states of the plant. By reshaping the structure commonly used in literature the similarities between the resulting scheme and what is made in model following control are utilized to get a pure nonlinear feedforward system which is completely decoupled from system outputs. This permits the application of the nonlinear control law when knowledge of the system states is not available. Due to the strict separation of plant and reference dynamics in the proposed approach a stability analysis of the reference system can be simplified. This new control scheme has been used for the control of an unmanned helicopter demonstrating its applicability. Results of these flight-test are presented in this paper.

To achieve identification of the flight mechanical parameters of aircraft experimental techniques like free flight or wind tunnel tests are still essential, even if the numerical methods are getting better. But the mentioned techniques have both their disadvantages: On the one hand because the mounting of the model during wind tunnel measurements causes interference to the flow. On the other hand coupling effects caused by the movement of the aircraft in the flow can only determined with high costs – in some cases it is even not possible. The disadvantages of the free flight techniques consist of no reproducible conditions (atmospheric disturbances), high costs and the risk of manned test flights. The goal of this work which was conducted at the Chair of Flight Dynamics at the RWTH Aachen University was the creation of a reproducible free flight environment for the cost effective Identification of main flight mechanical parameters even in an early design stage. Therefore the advantages of the free flight techniques will be combined with the advantages of the Wind Tunnel techniques by bringing the free flight into the wind tunnel under laboratory conditions. The position and attitude of the aircraft is affiliated by a 3D Camera System with high frequency and accuracy. Hence, the aircraft must only be equipped with sensor for the control surface positions and the revolution of the engine. The aircraft and the whole process are controlled by a real time system, which is implemented in Matlab/Simulink before. An adaptive identification algorithm, based on a regression in the frequency domain, generates the required excitation manoeuvre and analyses them in real time. Because the algorithm is adaptable, it needs only little a priori knowledge of the aircraft characteristics. The manoeuvre will be adapted until they fit most exactly to the eigenfrequency of the aircraft. The control algorithm has the function to reposition the aircraft after an identification manoeuvre and to trim. Additional, the algorithm takes control of the aircraft if it reaches the border of the free stream and tries to reposition it in the center of the wind tunnel. Because of the high non linearity and the agility of the aircraft the dynamic inversion is used. This is enhanced by a pseudo control hedging to avoid non linear rate- and deflection limits and to avoid the inversion of the dynamic of the actuator. As this combination is not very robust against uncertainties in the parameters, as they appear especially in this case, additionally adaptive terms in form of neural networks where included. After the free flight experiment an identification based on offline algorithms is conducted. Because of the higher resources even nonlinear models and better filter algorithms can be used. Because of the sensor concept, drift and bias in the signals do not exist. Therefore an equation error method is adequate. The Validation exemplary takes place with an aircraft in the wind tunnel of the Chair of Flight Dynamics.

This work deals with finding the appropriate gains for the flight controller to satisfy the specific requirements and to check how this controller is robust to different uncertainties. Its necessary to reduce the present complexity of the Flight Control Systems (F.C.S.) to have better performance, handling qualities & cost reduction. Dynamic Inversion is an excellent tool to achieve this task. The inner loop controllers is based on Dynamic Inversion which provides decoupling between the nonlinearities inside the model and there by reducing system complexity .Gains of the inner controller were optimized and the robustness of the controller was tested under various uncertainties. Validerat; 20101217 (root)

An adaptive drug delivery design is presented in this paper using neural networks for effective treatment of infectious diseases. The generic mathematical model used describes the coupled evolution of concentration of pathogens, plasma cells, antibodies and a numerical value that indicates the relative characteristic of a damaged organ due to the disease under the influence of external drugs. From a system theoretic point of view, the external drugs can be interpreted as control inputs, which can be designed based on control theoretic concepts. In this study, assuming a set of nominal parameters in the mathematical model, first a nonlinear controller (drug administration) is designed based on the principle of dynamic inversion. This nominal drug administration plan was found to be effective in curing "nominal model patients" (patients whose immunological dynamics conform to the mathematical model used for the control design exactly. However, it was found to be ineffective in curing "realistic model patients" (patients whose immunological dynamics may have off-nominal parameter values and possibly unwanted inputs) in general. Hence, to make the drug delivery dosage design more effective for realistic model patients, a model-following adaptive control design is carried out next by taking the help of neural networks, that are trained online. Simulation studies indicate that the adaptive controller proposed in this paper holds promise in killing the invading pathogens and healing the damaged organ even in the presence of parameter uncertainties and continued pathogen attack. Note that the computational requirements for computing the control are very minimal and all associated computations (including the training of neural networks) can be carried out online. However it assumes that the required diagnosis process can be carried out at a sufficient faster rate so that all the states are available for control computation. � 2009 Elsevier Ireland Ltd. All rights reserved.

A new structured model-following adaptive approach is presented in this paper to achieve large attitude maneuvers of rigid bodies. First, a nominal controller is designed using the dynamic inversion philosophy. Next, a neuro-adaptive design is proposed to augment the nominal design in order to assure robust performance in the presence of parameter inaccuracies as well as unknown constant external disturbances. The structured approach proposed in this paper (where kinematic and dynamic equations are handled separately), reduces the complexity of the controller structure. From simulation studies. this adaptive controller is found to be very effective in assuring robust performance. (C) 2008

Electrical propulsion systems allow broader a class of spacecraft trajectories than conventional chemical propulsion. But because low-thrust propulsion systems induce limited controllability for the spacecraft and increase overall trajectory transfer duration, it is generally useful to use gravitational assistances. Gravity assists allow reducing both the consumption and the mission duration. The optimisation of continuous thrust trajectory remains a terrible task. General methods may be difficult to converge. In addition, the optimisation of the scenario, i.e. seeking the optimal planet sequence for the gravity assists, is never included in the optimisation process. The planet sequence is very likely not optimal. Mission analysts usually consider several different planet sequences. The trade-off between the different solutions permit identifying a promising planet sequence. This approach is however time consuming. The purpose of this thesis is to provide method to design optimal scenarios. This thesis proposes methods for the determination of the optimal scenario. Two approaches have been considered. The first approach considers the problem as an integer programming problem, when many sequences are considered a-priori. A low-thrust trajectory model has been designed, using inversion dynamics approach, to compute efficiently approximate solutions to the low-thrust trajectory transfer problem. This low-thrust model uses coast arcs to minimise the consumption, but also to increase the degree of freedom for satisfying terminal constraints. We set up an algorithm with polynomial complexity to solve the multi-gravity-assist low-thrust problem. The computational cost is limited using pruning constraints to reduce the size of the search boxes. The second approach formulates the problem as an indirect continuous optimal control problem. The dynamic includes all major gravitational bodies. Swing-bys are not introduced with intermediate constraint, but implicit with the dynamic and the appropriate control. We show that usual direct and indirect methods have difficult convergence for this problem. Using a second order gradient method, we seek the optimal control that transfers the spacecraft to its destination while in a multi-body dynamics. In some case, the optimal control manages to introduce gravity assist on the trajectory. The scenario is then given a posteriori, once an optimal control has been found.; Cette thèse porte sur la conception de trajectoires interplanétaires, à poussée faible. Les systèmes de propulsion électriques, à poussée faible ou continue, ont permis d'accroître significativement les possibilités de trajectoires, au détriment de mission plus longues. La poussée faible limite également la manoeuvrabilité du système. Afin de parer à ces inconvénients, on utilise généralement des manoeuvres d'assistances gravitationnelles, pour ainsi réduire la consommation et la durée de transfert de la sonde. Le rôle de l'analyste mission est donc de déterminer le meilleur scénario (la séquence de planètes à visiter). De nos jours, ce problème est résolu de manière expérimentale et heuristique. Cependant, bien que la trajectoire produite soit optimale à scénario donné, il n'y a aucune garantie que le scénario en lui-même soit optimal. De plus, cette approche est relativement fastidieuse. Notre objectif a donc été de mettre en place des outils et méthodes permettant de trouver des scénario optimaux pour un objectif fixé. Durant cette thèse, nous avons suivit 2 approches. La première approche consiste à considérer le problème comme étant un problème d'optimisation globale, à variables discrètes. Un ensemble de scénario est étudié à priori. Pour simplifier et faciliter la recherche de séquences, on a modélisé le problème de transfert à poussée faible, en utilisant un principe d'inversion dynamique. Ce modèle utilise des arcs balistiques pour minimiser la consommation, et introduire des degrés de liberté supplémentaires pour satisfaire des contraintes terminales. On a mis au point un algorithme de complexité polynomiale pour résoudre le problème. Afin de réduire le coût calculatoire, nous avons mis en place des contraintes de " pruning " permettant de réduire l'espace de recherche. La deuxième approche consiste à formuler le problème comme un problème de commande optimale, où la dynamique inclut les principaux corps perturbateurs. Le scénario est alors déterminé à postériori. On résoud numériquement le problème au N corps. On montre que les méthodes indirectes (Pontryaguin) et directes (Collocation, Transcription) ne nous permettent pas de résoudre ce problème. On a donc mis au point un solveur de deuxième ordre respectant à la fois les conditions d'optimalité et de précision connues des méthodes indirectes, et des propriétés de robustesse généralement attribué aux méthodes directes.

Electrical propulsion systems allow broader a class of spacecraft trajectories than conventional chemical propulsion. But because low-thrust propulsion systems induce limited controllability for the spacecraft and increase overall trajectory transfer duration, it is generally useful to use gravitational assistances. Gravity assists allow reducing both the consumption and the mission duration. The optimisation of continuous thrust trajectory remains a terrible task. General methods may be difficult to converge. In addition, the optimisation of the scenario, i.e. seeking the optimal planet sequence for the gravity assists, is never included in the optimisation process. The planet sequence is very likely not optimal. Mission analysts usually consider several different planet sequences. The trade-off between the different solutions permit identifying a promising planet sequence. This approach is however time consuming. The purpose of this thesis is to provide method to design optimal scenarios. This thesis proposes methods for the determination of the optimal scenario. Two approaches have been considered. The first approach considers the problem as an integer programming problem, when many sequences are considered a-priori. A low-thrust trajectory model has been designed, using inversion dynamics approach, to compute efficiently approximate solutions to the low-thrust trajectory transfer problem. This low-thrust model uses coast arcs to minimise the consumption, but also to increase the degree of freedom for satisfying terminal constraints. We set up an algorithm with polynomial complexity to solve the multi-gravity-assist low-thrust problem. The computational cost is limited using pruning constraints to reduce the size of the search boxes. The second approach formulates the problem as an indirect continuous optimal control problem. The dynamic includes all major gravitational bodies. Swing-bys are not introduced with intermediate constraint, but implicit with the dynamic and the appropriate control. We show that usual direct and indirect methods have difficult convergence for this problem. Using a second order gradient method, we seek the optimal control that transfers the spacecraft to its destination while in a multi-body dynamics. In some case, the optimal control manages to introduce gravity assist on the trajectory. The scenario is then given a posteriori, once an optimal control has been found.; Cette thèse porte sur la conception de trajectoires interplanétaires, à poussée faible. Les systèmes de propulsion électriques, à poussée faible ou continue, ont permis d'accroître significativement les possibilités de trajectoires, au détriment de mission plus longues. La poussée faible limite également la manoeuvrabilité du système. Afin de parer à ces inconvénients, on utilise généralement des manoeuvres d'assistances gravitationnelles, pour ainsi réduire la consommation et la durée de transfert de la sonde. Le rôle de l'analyste mission est donc de déterminer le meilleur scénario (la séquence de planètes à visiter). De nos jours, ce problème est résolu de manière expérimentale et heuristique. Cependant, bien que la trajectoire produite soit optimale à scénario donné, il n'y a aucune garantie que le scénario en lui-même soit optimal. De plus, cette approche est relativement fastidieuse. Notre objectif a donc été de mettre en place des outils et méthodes permettant de trouver des scénario optimaux pour un objectif fixé. Durant cette thèse, nous avons suivit 2 approches. La première approche consiste à considérer le problème comme étant un problème d'optimisation globale, à variables discrètes. Un ensemble de scénario est étudié à priori. Pour simplifier et faciliter la recherche de séquences, on a modélisé le problème de transfert à poussée faible, en utilisant un principe d'inversion dynamique. Ce modèle utilise des arcs balistiques pour minimiser la consommation, et introduire des degrés de liberté supplémentaires pour satisfaire des contraintes terminales. On a mis au point un algorithme de complexité polynomiale pour résoudre le problème. Afin de réduire le coût calculatoire, nous avons mis en place des contraintes de " pruning " permettant de réduire l'espace de recherche. La deuxième approche consiste à formuler le problème comme un problème de commande optimale, où la dynamique inclut les principaux corps perturbateurs. Le scénario est alors déterminé à postériori. On résoud numériquement le problème au N corps. On montre que les méthodes indirectes (Pontryaguin) et directes (Collocation, Transcription) ne nous permettent pas de résoudre ce problème. On a donc mis au point un solveur de deuxième ordre respectant à la fois les conditions d'optimalité et de précision connues des méthodes indirectes, et des propriétés de robustesse généralement attribué aux méthodes directes.

We develop an elliptical approximation method of the seismic source to improve the efficiency of both kinematic and dynamic inversions. We apply it to the 2000 Tottori Japan earthquake.A non-linear kinematic inversion is first computed with the neighbourhood algorithm (NA). It converges on a slip distribution modeled by two elliptical patches and reproduces very well the strong motion records. The solution is non-unique.We then apply the method to dynamic inversions. The dynamic rupture propagation is modeled with a finite difference method and the friction law is of the slip weakening type. We compute a trial and error dynamic inversion for both the asperity and the barrier models. The latter is easier to implement and matches better the observed records. The computed seismic moment is compatible with the magnitude of the Tottori earthquake and the fracture energy is similar to that estimated by other studies.The dynamic inversion is implemented with the NA for the barrier model. The results correspond to a better fit of the observed data and illustrate the non-unicity of the dynamic solution.; Nous développons une méthode d'approximation elliptique de la source des séismes qui améliore l'efficacité des inversions cinématiques et dynamiques. Nous l'appliquons au séisme de Tottori (Japon 2000).Une inversion cinématique non-linéaire est d'abord résolue par l'algorithme de voisinage (NA). Elle converge vers une distribution de glissement modélisée par deux ellipses et reproduit très bien les données de mouvement fort. La solution est non unique.Nous étendons la méthode aux inversions dynamiques. La propagation dynamique de la rupture est modélisée en différences finies et la loi de frottement est du type affaiblissement de glissement.Nous réalisons une inversion par essai-erreur pour les modèles d'aspérité et de barrière. Ce dernier permet une implémentation facile et un meilleur accord avec les données observées. Le moment sismique calculé est compatible avec la magnitude du séisme et l'énergie de rupture est proche de celle d'autres études.Nous automatisons l'inversion dynamique pour le modèle de barrière par le NA. Les résultats d'inversion montrent un meilleur accord avec les données et illustrent la non-unicité de la solution dynamique.

We develop an elliptical approximation method of the seismic source to improve the efficiency of both kinematic and dynamic inversions. We apply it to the 2000 Tottori Japan earthquake.A non-linear kinematic inversion is first computed with the neighbourhood algorithm (NA). It converges on a slip distribution modeled by two elliptical patches and reproduces very well the strong motion records. The solution is non-unique.We then apply the method to dynamic inversions. The dynamic rupture propagation is modeled with a finite difference method and the friction law is of the slip weakening type. We compute a trial and error dynamic inversion for both the asperity and the barrier models. The latter is easier to implement and matches better the observed records. The computed seismic moment is compatible with the magnitude of the Tottori earthquake and the fracture energy is similar to that estimated by other studies.The dynamic inversion is implemented with the NA for the barrier model. The results correspond to a better fit of the observed data and illustrate the non-unicity of the dynamic solution., Nous développons une méthode d'approximation elliptique de la source des séismes qui améliore l'efficacité des inversions cinématiques et dynamiques. Nous l'appliquons au séisme de Tottori (Japon 2000).Une inversion cinématique non-linéaire est d'abord résolue par l'algorithme de voisinage (NA). Elle converge vers une distribution de glissement modélisée par deux ellipses et reproduit très bien les données de mouvement fort. La solution est non unique.Nous étendons la méthode aux inversions dynamiques. La propagation dynamique de la rupture est modélisée en différences finies et la loi de frottement est du type affaiblissement de glissement.Nous réalisons une inversion par essai-erreur pour les modèles d'aspérité et de barrière. Ce dernier permet une implémentation facile et un meilleur accord avec les données observées. Le moment sismique calculé est compatible avec la magnitude du séisme et l'énergie de rupture est proche de celle d'autres études.Nous automatisons l'inversion dynamique pour le modèle de barrière par le NA. Les résultats d'inversion montrent un meilleur accord avec les données et illustrent la non-unicité de la solution dynamique.

The paper is devoted to the problem of mapping fractured and cavernous fractured reservoirs of the tutleym series within the Krasnoleninsk arc. It is shown that the most perspective deposits are those of the low-tytleym arc. The presence of relation between reservoir and acoustic properties of the rocks involved is stated. For reservoirs to be mapped the results of dynamic inversion of time sections are used.

International audience; For transport aircraft, the primary control objective for an autopilot system engaged during approach and landing is relative to the flight-path tracking on the basis of highly simplified linear models of flight dynamics. The dynamics governing the flight-path of an aircraft are in general highly nonlinear and involve complex physics for which no accurate models are available. In the past decades, some new nonlinear control design techniques appeared of interest for the development of improved control schemes for the flight-path tracking mode. In this communication, two nonlinear control techniques are used for the design of flight-path tracking control laws for a transport aircraft. A first control technique adopts a classical nonlinear dynamic inversion control scheme where enhanced robustness is introduced, and a second control scheme based on the backstepping technique is developed. These two approaches are compared in terms of applicability, complexity and robustness with respect to modeling inaccuracies and external perturbations. Finally, simulation results are displayed and discussed.

In this paper, we study the trajectory space of the PVTOL aircraft. We show that, due to the non-minimum phase nature of the system, more aggressive trajectories may be tracked with respect to the simplified differentially flat model. Given bounded C2trajectories of the center of gravity, we show that there exists a bounded roll trajectory which implements them. We compute an approximation of such roll trajectory using a Newton method for nonlinear optimization based on a trajectory tracking projection operator.

A generic nonlinear mathematical model describing the human immunological dynamics is used to design an effective automatic drug administration scheme. Even though the model describes the effects of various drugs on the dynamic system, this work is confined to the drugs that kill the invading pathogen and heal the affected organ. From a system theoretic point of view, the drug inputs can be interpreted as control inputs, which can be designed based on control theoretic concepts. The controller is designed based on the principle of dynamic inversion and is found to be effective in curing the 'nominal model patient' by killing the invading microbes and healing the damaged organ. A major advantage of this technique is that it leads to a closed-form state feedback form of control. It is also proved from a rigorous mathematical analysis that the internal dynamics of the system remains stable when the proposed controller is applied. A robustness study is also carried out for testing the effectiveness of the drug administration scheme for parameter uncertainties. It is observed from simulation studies that the technique has adequate robustness for many 'realistic model patients' having off-nominal parameter values as well. � Indian Institute of Science.

High performance aircraft of the future will be designed to be lighter, more maneuverable, and operate over an ever expanding flight envelope. This set of conditions will necessarily mean highly flexible vehicles operating in nonlinear regimes. A methodology proposed to better optimize their responses to both pilot input and external disturbances, as well as to decrease the cost of vehicle design is the novel dynamic inversion. The attractiveness of this methodology lies in the fact that the inherent nonlinearities of the problem and the coupled nature of flexible dynamics are explicitly considered. The contribution of this work to the state of the art is predicated on the development and application of the novel dynamic inversion methodology to handle highly flexible aircraft in an integrated flight/structural mode control manner. The unprecedented small separation between rigid body and flexible dynamics as well as the reciprocal interaction between them due to flight control action are the key elements of the aircraft model. The novel approach to the nonlinear dynamic inversion allows the methodology to more intelligently handle flexible dynamics in the context of the dual objectives of integrated flight/SMC control by altering flexible mode damping without cancellation; thus, improving disturbance response and avoiding the potentially destabilizing effect of pole cancellation close to the j-omega-axis in case of modeling uncertainty. The necessary level of model complexity for design has been established with particular attention given to understanding physics. The effect of uncertainty in the structural mode dynamics has been addressed. Further contribution of this work addresses the issue of stability of the dynamic systems driven by nonlinear controllers. One result shows how assessing stability of an n-dimensional system can be reduced to checking stability of a two-dimensional one using algebraic expressions that are based on the vehicle characteristics such as aerodynamic coefficients. This reduces a complicated dynamical problem to something purely algebraic and manageably complex. Another approach is based on algorithmically finding a local Lyapunov function using sum of squares. The presented results are the first to address the question of stability for the nonlinear dynamic inversion in the presence of flexible dynamics.

The subject of this research work concerns the control of non linear systems and applies to the ground control and guidance of civil transportation aircraft. A model of the ground dynamics of the aircraft was elaborated and validated compared with real data. Global functional architecture of the ground control systems for a civil transportation aircraft was proposed and led to the synthesis of guidance and control laws concerning the longitudinal and lateral aircraft movements on the ground. The rollout phase at the landing was more particularly studied. Furthermore, this thesis was the occasion to implement the Dynamic Inversion technique for the control laws synthesis as well as the neural techniques for trajectories generation. The validation by non linear simulations and by flight tests confirm the performance of the proposed control laws and the viability of the associated functional architectures; Le thème de ce travail de recherche concerne la commande des systèmes non linéaires et s'applique à la conduite des mouvements au sol des avions de transport. Un modèle de la dynamique des mouvements de l'avion au sol a été élaboré et validé par comparaison avec des données réelles. Une architecture globale des systèmes de pilotage au sol des avions de transport a été proposé et a conduit à la synthèse de lois de pilotage et de guidage en manuel et en automatique concernant les mouvements longitudinaux et latéraux de l'avion au sol. La phase de roulage à l'atterrissage a été plus particulièrement étudiée. De plus, cette thèse a été l'occasion de mettre en ¿uvre la technique de synthèse de lois de commande par inversion de la dynamique ainsi que les techniques neuronales pour la génération de trajectoires de consigne. Les validations par des simulations non linéaires et par des essais en vol confirment les performances des lois de commande proposées et la viabilité des architectures fonctionnelles associées.

A methodology is proposed to control the transient sway and residual oscillation of a payload carried by an overhead crane. The design approach is based on a linearised model of the crane and consists of dampening the linearised system by an observer-based controller and applying a dynamic inversion procedure in order to assure a predetermined oscillation free polynomial motion law for the payload. Polynomial functions are adopted in order to guarantee that the input function has a continuous derivative of an arbitrary order. Moreover, the motion time can be minimised, taking into account constraints on the actuators, by means of a simple bisection algorithm. Parameter uncertainties are taken into account during the whole design procedure. Simulation results, based on a nonlinear crane model, show how the method is also effective when the payload is hoisted or lowered during the motion, and when friction effects are considered.

A closed-loop control allocation method is proposed for a class of aircraft with multiple actuators. Nonlinear dynamic inversion is used to design the baseline attitude controller and derive the desired moment increment. And a feedback loop for the moment increment produced by the deflections of actuators is added to the angular rate loop, then the error between the desired and actual moment increment is the input of the dynamic control allocation. Subsequently, the stability of the closed-loop dynamic control allocation system is analyzed in detail. Especially, the closed-loop system stability is also analyzed in the presence of two types of actuator failures: loss of effectiveness and lock-in-place actuator failures, where a fault detection subsystem to identify the actuator failures is absent. Finally, the proposed method is applied to a canard rotor/wing (CRW) aircraft model in fixed-wing mode, which has multiple actuators for flight control. The nonlinear simulation demonstrates that this method can guarantee the stability and tracking performance whether the actuators are healthy or fail.