State constrained tracking control for nonlinear systems

Abstract This work addresses the model reference tracking control problem. It aims to highlight the encountered difficulties and the proposed solutions to achieve the tracking objective. Based on a literature overview of linear and nonlinear reference tracking, the achievements and the limitations of the existing strategies are highlighted. This motivates the present work to propose clear control algorithms for perfect and approximate tracking controls of nonlinear systems described by Takagi-Sugeno models. First, perfect nonlinear tracking control is addressed and necessary structural conditions are stated. If these conditions do not hold, approximate tracking control is proposed and the choice of the reference model to be tracked as well as the choice of the criterion to be minimized are discussed with respect to the desired objectives. The case of constrained control input is also considered in order to anticipate and counteract the effect of the control saturation

Model predictive cooperative localization control of multiple UAVs using potential function sensor constraints: a workflow to create sensor constraint based potential functions for the control of cooperative localization scenarios with mobile robots.

The global localization of multiple mobile robots can be achieved cost efficiently by localizing one robot globally and the others in relation to it using local sensor data. However, the drawback of this cooperative localization is the requirement of continuous sensor information. Due to a limited sensor perception space, the tracking task to continuously maintain this sensor information is challenging. To address this problem, this contribution is presenting a model predictive control (MPC) approach for such cooperative localization scenarios. In particular, the present work shows a novel workflow to describe sensor limitations with the help of potential functions. In addition, a compact motion model for multi-rotor drones is introduced to achieve MPC real-time capability. The effectiveness of the presented approach is demonstrated in a numerical simulation, an experimental indoor scenario with two quadrotors as well as multiple indoor scenarios of a quadrotor obstacle evasion maneuver

Adaptive Control of Hysteretic Robotic arm in Operational Space

The focus of the current article is on Operational Space Control of a single degree of freedom robotic arm with hysteretic joint behaviour due to actuation by a single Shape Memory Alloy (SMA) wire. A Closed Loop Inverse Kinematics Algorithm is used in the outer loop with Adaptive joint control in the inner loop. A composite stability analysis is used to analyse the stability of the closed loop system and finally successfully validated through simulation study

Adaptive Control of Robotic arm with Hysteretic Joint

This article addresses the problem of control of robotic arm with a hysteretic joint behavior. The mechanical design of the one-degree of freedom robotic arm is presented where the joint is actuated by a Shape Memory Alloy (SMA) wire. The SMA wire based actuation of the joint makes the robotic arm lightweight but at the same time introduces hysteresis type nonlinearities. The nonlinear dynamic model of the robotic arm is introduced and an Adaptive control solution is presented to perform the joint reference tracking in the presence of unknown hysteresis behavior. The Lyapunov stability analysis of the closed loop system is presented and finally proposed adaptive control solution is validated through simulation study on the proposed nonlinear hysteretic robotic arm

Hierarchical control of aerial manipulation vehicle

Hierarchical Control of the Aerial Manipulator is treated here. The modelling aspect of the highly coupled Aerial Vehicle which includes Quadrotor and manipulator is discussed. The control design to perform tasks in operational space is addressed along with stability discussion. The simulation studies are successfully performed to validate the design methodology

Fault tolerant control for Takagi-Sugeno nonlinear systems

Cette thèse porte sur la représentation T-S des systèmes non linéaires et les non-linéarités qui leur sont associées (saturation et paramètres variants dans le temps) pour la commande et le diagnostic. Ainsi, une nouvelle approche utilisant la transformation par secteurs non linéaires permet de ré-écrire le système sous forme polytopique en prenant en compte la présence de paramètres variants dans le temps. Cette forme polytopique est ensuite utile pour la synthèse d'observateurs assurant l'estimation simultanée de l'état et des paramètres du système. Une application au diagnostic est également considérée en comparant les valeurs des paramètres estimés en ligne avec leurs valeurs nominales supposées connues et représentatives du mode de fonctionnement non défaillant. Concernant la commande, la contrainte de saturation est représentée sous forme de modèle T-S et est intégrée au modèle du système. La synthèse de plusieurs lois de commande assurant la stabilité du système bouclé, en prenant en compte les limites de saturation est proposée. La poursuite de modèle de référence est également traitée avec la mise en évidence des conditions structurelles de poursuite pour les modèles non linéaires sous forme T-S. L'accent est mis sur les différents critères de choix de commande en fonction des buts recherchésA first contribution of this thesis is to propose a systematic procedure to deal with the state and parameter estimation for nonlinear time-varying systems. It consists in transforming the original system into a T-S model with unmeasurable premise variables using the sector nonlinearity transformation. Then a joint state and parameter observer is designed and the convergence conditions of the joint state and parameter estimation errors are established. The second contribution of this thesis is the stabilization problem under saturation constraints. In fact, we aim to present a new approach for the saturation nonlinearity study, where the sector nonlinearity transformation is used to represent the nonlinear behaviour of a saturated actuator under a T-S form. The T-S representation of the saturation is used to integrate the limitation constraints into the control synthesis, such that the system stability is ensured and the controller gains are calculated according to the saturation level. The model reference tracking control problem is also addressed. It aims to highlight the encoutered difficulties and the proposed solutions to achieve the tracking objective. Through analytical studies, by presenting clear structural conditions and control strategies, we try to point and answer some major interogations, that are : "how the model reference is to be chosen ? " and "which tracking criterion to consider to achieve a certain objective ? ". The case of constrained control input is also considered with a special focus on the anticipation for the saturated contro

Commande tolérante aux défauts de systèmes non linéaires représentés par des modèles de Takagi-Sugeno

A first contribution of this thesis is to propose a systematic procedure to deal with the state and parameter estimation for nonlinear time-varying systems. It consists in transforming the original system into a T-S model with unmeasurable premise variables using the sector nonlinearity transformation. Then a joint state and parameter observer is designed and the convergence conditions of the joint state and parameter estimation errors are established. The second contribution of this thesis is the stabilization problem under saturation constraints. In fact, we aim to present a new approach for the saturation nonlinearity study, where the sector nonlinearity transformation is used to represent the nonlinear behaviour of a saturated actuator under a T-S form. The T-S representation of the saturation is used to integrate the limitation constraints into the control synthesis, such that the system stability is ensured and the controller gains are calculated according to the saturation level. The model reference tracking control problem is also addressed. It aims to highlight the encoutered difficulties and the proposed solutions to achieve the tracking objective. Through analytical studies, by presenting clear structural conditions and control strategies, we try to point and answer some major interogations, that are : "how the model reference is to be chosen ? " and "which tracking criterion to consider to achieve a certain objective ? ". The case of constrained control input is also considered with a special focus on the anticipation for the saturated control.Cette thèse porte sur la représentation T-S des systèmes non linéaires et les non-linéarités qui leur sont associées (saturation et paramètres variants dans le temps) pour la commande et le diagnostic. Ainsi, une nouvelle approche utilisant la transformation par secteurs non linéaires permet de ré-écrire le système sous forme polytopique en prenant en compte la présence de paramètres variants dans le temps. Cette forme polytopique est ensuite utile pour la synthèse d'observateurs assurant l'estimation simultanée de l'état et des paramètres du système. Une application au diagnostic est également considérée en comparant les valeurs des paramètres estimés en ligne avec leurs valeurs nominales supposées connues et représentatives du mode de fonctionnement non défaillant. Concernant la commande, la contrainte de saturation est représentée sous forme de modèle T-S et est intégrée au modèle du système. La synthèse de plusieurs lois de commande assurant la stabilité du système bouclé, en prenant en compte les limites de saturation est proposée. La poursuite de modèle de référence est également traitée avec la mise en évidence des conditions structurelles de poursuite pour les modèles non linéaires sous forme T-S. L'accent est mis sur les différents critères de choix de commande en fonction des buts recherchés

New Trends in Observer-based Control: An Introduction to Design Approaches and Engineering Applications, Chapter 13: Observer-based Event-triggered Attack-Tolerant Control Design for Cyber-physical Systems

In the following chapter, we first introduce an appropriate model associating paradigms from control theory and computer science (system subject to both physical attacks and sensors/actuators attacks via the connected network, i.e., false-data injection attacks on actuators/sensors). Then, inspired by a combination between the classical fault-tolerant control (FTC) approach and the event-triggered control, an observer-based attack-tolerant control solution is proposed. The aim of our work is, first, to establish theoretical foundations for the development of model-based monitoring and attack-tolerant control for reliable deployment of a large number of advanced Cyber-Physical Systems

A short Survey on the Cyber Security in Control Systems

In the present survey paper, we give a short, yet exhaustive state-of-the-art about the cyber-security applied to control systems, especially the event-based strategy. Indeed, in the past few years, due to a highest degree of connectivity in modern systems, new related control-specific cyber-physical systems security challengesarise and novel approaches integrating the cyber aspect are developed.Our goal in this paper is then to provide an overview of attack-modeling and security analysis approaches in recent works thatexplore networked control systems subject to cyber-attacks attacks. To this end, we look at the control, estimation, and modeling problems

On the Event-based Attack-tolerant Control: A Polytopic Representation

In the present contribution, we present a new event-based control representation. Based on the polytopic approach, more specifically the sector nonlinear transformation, an event-based attack-tolerant control, and scheduling co-design strategy are proposed. From the event triggering definition (sample-and-hold strategy), polytopic writing of the event-triggered feedback control is first presented and then incorporated into the system dynamics for analysis. Our goal is to present a unique model that is able to deal with the co-design problem simultaneously and that can be handled by classical control synthesis tools. The novel representation, including data deception and attack tolerant control is formulated as a BMI optimization problem ensuring both stability and some level performance requirements (L2 attenuation of the cyber-attack)