Seminars - MAC
Seminars in Toulouse in which MAC team members are involved.
21-23 November 2018
2nd DECOD Workshop - Delays and constraints in distributed parameter systems
2 July 2018, 11:00pm, LAAS - Salle Tourmalet
Numerical Computational Techniques for Nonlinear Optimal Control - Slides
by Yasuaki Oishi
Abstract: In this talk, I present the stable-manifold method, an effective method for nonlinear optimal control introduced by Sakamoto and van der Schaft in 2008, and propose two numerical computational techniques for its improvement. The first technique is for generation of points on the stable manifold in a robust way against numerical errors. There, a special numerical method that preserves Hamiltonian is used to solve a differential equation sensitive to numerical errors. The second technique is a sort of shooting method to generate a point corresponding to the desired system state. These techniques are used for optimal swing-up of a pendulum and successfully give a swing-up trajectory with multiple swings. This is a joint work with Noboru Sakamoto and Takuto Nakamura.
27 June 2018, 2:00pm, LAAS - Salle du Conseil
Formal Verification of Convex Optimization Algorithms For Model Predictive Control
by Raphaël Cohen
Abstract: The efficiency of modern optimization methods, coupled with increasing computational resources, has led to the possibility of real-time optimization algorithms acting in safety critical roles. However, this cannot happen without addressing proper attention to the soundness of these algorithms. This work discusses the formal verification of convex optimization algorithms with a particular emphasis on receding-horizon controllers. Additionally, we demonstrate how theoretical proofs of real-time optimization algorithms can be used to describe functional properties at the code level, thereby making it accessible for the formal methods community. In seeking zero-bug software, we use the Credible Autocoding scheme. We focused our attention on the ellipsoid algorithm solving second-order cone programs (SOCP). In addition to this, we present a floating-point analysis of the algorithm and give a framework to numerically validate the method.
19 June 2018, 10:45am, LAAS - Salle Europe
Lp stability of networked control systems implemented on WirelessHART
by Dragan Nesic
Abstract: Control systems in which sensor/actuator signals are sent via a communication network are increasingly important in various areas, such as X-by-wire technologies in the aerospace and automotive industries, smart grid, vehicle platoons, swarms of UAVs and control of large irrigation networks. Such networked control systems (NCS) are much harder to design and analyse because the communication network introduces a range of undesirable effects into the closed loop system, such as the sampling jitter, quantized signals, the need for signal scheduling, data dropouts, and so on. In the past decade, a large body of research addressed various issues in NCS via “generic” network models which are sometimes hard to apply to NCS with specific networks, such as CAN, Flexray or WirelessHART. In this talk I will concentrate on control oriented modelling of NCS with WirelessHART networks and then present results on an emulation oriented approach for achieving Lp stabilisation of such systems. We show that our results are less conservative (in an appropriate sense) than prior emulation results that do not exploit the specific network structure in the analysis.
19 June 2018, 9:30am, LAAS - Salle Europe
Glocal (Global/Local) Control towards Smart Cities
by Shinji Hara
Abstract: There are many dynamical systems that can be regarded as hierarchical networked dynamical systems in a variety of fields related to smart cities. One of the ideas to treat those systems properly is "Glocal (Global/Local) Control," which means that the global purpose is achieved by only local actions of measurement and control. The background and idea of glocal control are explained by showing the control perspective of IoT (Internet of Things).
The key for realization of glocal control is hierarchical networked dynamical systems with multiple resolutions in time and space depending on the layer. After introducing a unified framework, its fundamental control theory such as stability and robust stability is provided. Then, we focus on how to design hierarchically decentralized controls with global/local objectives by aggregation. Through the talk we show the effectiveness of the theoretical results for applications to electric vehicle control and power network systems towards smart cities.
Slides GlocalControl_LAAS_June2018SH.pdf available in MAC team Intranet.
11 June 2018, 2pm, ENSEEIHT
28 May 2018, 2pm, ENSEEIHT
23 April 2018, 1:30pm, LAAS - Salle Tourmalet
Peak Effects in Stable Linear Difference Equations
by Pavel Shcherbakov
Abstract: We consider homogenous, linear, asymptotically stable scalar difference equations with constant coefficients and unit-norm initial conditions. First, it is shown that the solution may happen to deviate far away from the equilibrium point at finite time instants prior to converging to zero. Second, for a number of root distributions and initial conditions, exact values of deviations or lower bounds are provided. Several specific difference equations known from the literature are also analyzed and estimates of deviations are proposed. Possible generalizations are discussed and directions for future research are outlined.
17 April 2018, ONERA
International Workshop on Robust LPV Control Techniques and Anti-Windup Design
16 April 2018, 2pm, ENSEEIHT
5 April 2018, 2pm, LAAS - Salle du Conseil
Regulation of linear PDE's by P-I controller using a Lyapunov approach inspired by forwarding methods. Theory and application to the drilling case - Slides
by Alexandre Terrand-Jeanne
Abstract: Most of the existing results for the regulation of PDE's are based on semi-group and spectral theory. However, these results impose bounds on the control and the measurement operators. For instance, the boundary regulation of hyperbolic PDE employing control at the boundaries, can not be addressed. In order to deals with more general systems, we introduce a novel Lyapunov functionnal inspired by nonlinear forwarding technics. Our approach is then illustrated in the case of a drilling system.
8 March 2018, 11am, LAAS - Salle de Conférence
Lyapunov-based analysis of TDSs and PDEs
by Anton Selivanov
Abstract: I will briefly describe some resent results devoted to control and stability analysis of time-delay systems and PDEs. All results were obtained using Lyapunov(-Krasovskii) functionals whose properties are guaranteed by feasibility of certain linear matrix inequalities. First, I will talk about delay-induced stability – a phenomenon that occurs when a system cannot be stabilized using the output but can be stabilized using the output together with its delayed value. Then I’ll talk about the event-triggered control with a dwell time and predictor-based event-triggered control. A significant part of the talk will be devoted to control of PDEs. We will discuss event-triggered control of PDEs, relay control of PDEs, and input delay compensation using the idea of chain predictors. All the results were obtained jointly with Emilia Fridman.