Henk van Waarde has received an NWO Veni grant for his proposal “Kernel-based control theory of nonlinear systems”. Veni grants are part of the Talent Scheme by the Dutch Research Council. They are awarded to talented early-career researchers who have obtained their PhD in the last three years.

# Category: SCO

## SCO colloquium: Azka Burohman

**Title:**Dissipativity-preserving reduced-order modeling from data

**Abstract:**Reduced-order modeling from data with dissipativity preservation is discussed in this talk. Employing the data informativity framework, the dissipativity of all systems consistent with noisy data can be characterized by a data-based linear matrix inequality (LMI). Furthermore, semi-definite programming duality helps us to prove the existence of minimal and maximal solutions to the LMI. As in the classical bounded-real and positive-real balanced truncation, these extremal solutions play a role in the computation of well-approximating reduced-order models carrying the dissipativity property. As an additional advantage of using this balancing-type method, a priori error bounds of the reduced-order models are available.

## SCO colloquium: Juan Peypouquet

**Title:** A speed restart scheme for first order dynamics bearing second order information in time and space

**Abstract:** We present two techniques that can help stabilize otherwise erratic inertial methods. Combined, they can enhance the performance of accelerated methods, especially for functions with quadratic growth, for which the rate of linear convergence is improved.

## SCO colloquium: Amir Shakouri

**Title:** Prescribed-time control

**Abstract:** In terms of the user’s knowledge about the settling time, non-asymptotic controllers can be divided into three major categories of finite-time, fixed-time, and prescribed-time approaches. In finite-time schemes, it is only known that the system non-asymptotically converges at a finite time that is generally a function of the initial conditions. Fixed-time schemes provide an upper bound for the settling time, independently of initial conditions. However, in prescribed-time control, the settling time is commanded to the system, which means that the user is not only aware of the convergence moment but can arbitrarily specify it just by changing a parameter. It turns out that another interesting feature of prescribed-time controllers, apart from having an adjustable settling time, is their robustness to unknown dynamics for which no global bounds exist.

In this talk, after reviewing the state-of-the-art, some new unpublished results on the differential Riccati equation approaches to prescribed-time control are discussed (LQR and SDRE-based designs), and it is shown how they can be used for the stabilization of (partially) unknown nonlinear systems.

## SCO colloquium: Sutrisno

**Title:**Singular linear switched systems in discrete time: solution theory, reachability, and duality

**Abstract:**In this talk, solution theory for singular linear switched systems in discreet time with arbitrary switching signals will be presented. Based on the derived solution theory, reachability and controllability characterizations will be discussed for a fixed and known switching signal. Moreover, the duality between reachability and observability of this system class will also be discussed.

## SCO colloquium: Hamin Chang

**Title:** Model reference Gaussian process regression: data-driven output feedback controller

**Abstract:** Data-driven controls using Gaussian process regression have recently gained much attention. In such approaches, system identification by Gaussian process regression is mostly followed by model-based controller designs. However, the outcomes of Gaussian process regression are often too complicated to apply conventional control designs, which makes the numerical design such as model predictive control employed in many cases. To overcome the restriction, our idea is to perform Gaussian process regression to the inverse of the plant with the same input/output data for the conventional regression. With the inverse, one can design a model reference controller without resorting to numerical control methods. This talk considers single-input single-output (SISO) discrete-time nonlinear systems of minimum phase with relative degree one. It is highlighted that the model reference Gaussian process regression controller is designed directly from pre-collected input/output data without system identification.

## SCO colloquium: Arjan van der Schaft

**Title:**On the legacy of Jan Willems (talk given before for the Control History Forum, CSS Day, October 2022)

**Abstract:**The list of scientific contributions of Jan Willems spans a whole range of topics, including (input-output) stability theory, dissipativity theory, linear geometric control theory, identification, the behavioral approach to systems and control, physical systems theory, open stochastic systems, .. ; see the website https://homes.esat.

## SCO colloquium: Anne-Men Huijzer

**Title:**Networks of memristors and the effective memristor.

**Abstract:** Memristors, originally introduced by Chua in 1971, are resistors with a memory storage which are defined by a relationship between charge and flux. In this talk, an introduction of memristors will be given after which a way to model networks of memristors will be described. Furthermore, we show that the input output behavior of a network of memristors can be described by a memristor, the so-called effective memristor.

## SCO colloquium: Kanat Camlibel

**Title:**Scalable controllability analysis of structured systems

**Abstract:**This talk deals with strong structural controllability of structured networks. A structured network is a family of structured systems (called node systems) that are interconnected by means of a structured interconnection law. The node systems and their structured interconnection law are given by pattern matrices. We will show that a structured network is strongly structurally controllable if and only if an associated structured system is. This structured system will in general have a very large state space dimension, and therefore existing tests for verifying strong structural controllability are not tractable. The results we present circumvent this problem. We show that controllability can be tested by replacing the original network by a new network in which all original node systems have been replaced by (auxiliary) node systems with state space dimensions either 1 or 2. Hence, controllability of the original network can be verified by testing controllability of a structured system with state space dimension at most twice the number of node systems, regardless of the state space dimensions of the original node systems.

## SCO colloquium: Stephan Trenn

**Title:**About observers of hybrid systems

**Abstract:**I recently reviewed the very nice paper [1] by Pauline Bernard and Ricardo Sanfelice about an observer design for hybrid systems, whose ideas I would like to share with you. I will briefly recall the hybrid systems framework proposed by Goebel, Sanfelice and Teel [2]. Afterwards I will highlight the difficulties in designing an observer for these kind of systems, in particular, when the jump times cannot be observed directly. Then I explain the actual observer design proposed in [1].

*Submitted to Transaction on Automatic Control, full version available at https://hal. archives-ouvertes.fr/hal-*03736135 , 2022.

*Princeton University Press*, 2012