Lehrstuhl für Mechatronik in Maschinenbau und Fahrzeugtechnik (MEC)


Here you can find the list of seminars, meetings and events held by the Chair.

International Control e-Seminar

The International Control e-Seminar takes place monthly. For a possible participation, please contact Dr. Saeed Ahmed.

Date: 19.02.2021

Time: 3:00 PM CET (Central European Time)

Title: Interpolation-based Design of Stabilizing Controllers for Retarded and Neutral Delay Systems

Speaker: Hitay Özbay, Bilkent University, Ankara, Turkey

Event Link: https://attendee.gotowebinar.com/register/8497667287637907723

Abstract: A class of retarded and neutral time-delay systems is considered: the plant may have finitely many or infinitely many unstable poles. Stabilizing controllers are obtained from two different types of interpolation-based designs. Robustness to uncertainties in the interpolation is discussed. A parameterization of all stabilizing integral action controllers is obtained. Examples are given to illustrate this simple design procedure.

Biography: Hitay Özbay is a Professor of Electrical and Electronics Engineering at Bilkent University, Ankara Turkey. He received the B.Sc., M.Eng. and Ph.D. degrees from Middle East Technical University (1985), McGill University (1987), and University of Minnesota (1989), respectively. His prior academic affiliations include the University of Rhode Island (1989-1990), and The Ohio State University (1991—2006). Professor Özbay served as Associate Editor for many journals, including IEEE Transactions on Automatic Control (1997-1999), SIAM Journal on Control and Optimization (2011-2014), and Automatica (2001-2007, 2012 - 2019). He was a Vice-Chair of the IFAC Technical Committee on Networked Control Systems (2005-2011); and currently is a Vice-Chair of the IFAC Technical Committee on Linear Control Systems (2017-2023). He is was a member of the Board of Governors of the IEEE Control Systems Society (2017-2019), and also was a General Assembly member of the European Control Association (EUCA), (2013-2019). Dr. Özbay is a Fellow of IEEE.

Date: 15.01.2021

Time: 3:00 PM CET

Title: Optimality of Stationary and Deterministic Policies for Zero-Delay Coding of Rd-Valued Linear Markov Sources with Quadratic Cost

Speaker:  Meysam Ghomi (Department of Mathematics and Statistics, Queen's University, Kingston, Ontario, Canada)

Abstract: We study the optimal causal zero-delay coding of a stable linear Markov process, under a quadratic cost with a fixed communication rate constraint. The goal is to minimize the infinite horizon average distortion problem.
a) We establish the existence and structure of optimal quantization policies provided that the realized quantizers are those with convex code cells. In particular, an optimal quantization policy is shown to be stationary and deterministic.
b) We show that a finite time horizon performance of an optimal (Markov and deterministic) T-horizon coding policy approaches the infinite time horizon average-cost optimal cost at a rate of O(1/T). This result establishes explicit bounds on the performance of finite-memory or sliding-block encoders.

Date: 13.11.2020

Time: 3:00 PM CET

Title: Modeling and Control of COVID-19 Epidemic through Testing Policies

Speaker:  M. Umar b. Niazi (Gipsa-Lab (CNRS) and Inria Grenoble Rhone-Alpes)

Abstract: Testing to detect the infected cases in a population is one of the most important mechanisms to control an epidemic. It enables the government to isolate the detected infected cases that limit the disease transmission to the susceptible population. However, despite the significance of testing in the control of an epidemic, the recent literature on testing policies lacks the control-theoretic perspective. In this paper, an epidemic model that incorporates the testing rate as a control input is presented. The proposed model differentiates the undetected infected from the detected cases, where the detected cases are assumed to be removed from the disease spreading process in the population. First, the model is estimated and validated for the COVID-19 data of France. Then, two testing policies, best-effort strategy for testing (BEST) and constant optimal strategy for testing (COST), are proposed. The BEST policy is a suppression strategy that provides a lower bound on the testing rate such that the epidemic switches from a spreading to a non-spreading phase. The COST policy is a mitigation strategy that provides an optimal value of testing rate that minimizes the peak value of the infected population when the total stockpile of tests is limited. Both testing policies are evaluated by predicting the number of active intensive care unit (ICU) cases and the cumulative number of deaths due to COVID-19.

About the speaker:  Muhammad Umar B. Niazi is currently pursuing the Ph.D. degree in Automatic Control from Grenoble INP, Universite Grenoble-Alpes, France, and is affiliated with Gipsa-Lab (CNRS) and Inria Grenoble Rhone-Alpes. His research interests include largescale network systems, aggregated state observers, model reduction, and differential game theory. Mr. Niazi was a finalist for the Best Student Paper Award in European Control Conference 2019.

Date: 23.10.2020

Time: 3:00 PM CEST

Title: Modeling by Infinite Petri Nets

Speaker:  Dmitry A. Zaitsev (Odessa State Environmental University, Ukraine)

Abstract: Infinite Petri nets were introduced for modeling modern networks, clusters, computing grids, and clouds that also concerns automated manufacture, cellular automata, and biological systems. A finite specification of infinite nets has been offered in the form of a parametric multiset rewriting system that takes into consideration spatial structure on a plane and in multidimensional lattices. A composition and analysis technique has been developed for the investigation of infinite Petri nets. A case study of a square grid structure composition and analysis is presented. Parametric description of Petri nets, parametric representation of infinite systems for the calculation of place/transition invariants, and solving them in parametric form allowed the invariance proof for infinite Petri net models. Some additional analysis techniques based on graphs of transmissions and blockings are presented. Complex deadlocks has been revealed and classifies as: a loop of blockings; a chain of blockings ended on an already blocked vertex; because of isolation by neighboring blocked devices. Further generalization on multidimensional structures such as hypercube and hypertorus implemented. Torus structures play a key role in communication subsystems of super computers, clusters, and networks on chip. Generators of Petri net models developed and put on GitHub for public use. As a result of complex deadlocks disclosure, a possibility of network blocking via ill-intentioned traffic has been revealed. Prospects for further development of infinite Petri net theory are outlined.

About the speaker:  Dmitry A. Zaitsev received the Eng. degree in Applied Mathematics from Donetsk Polytechnic Institute, Donetsk, Ukraine, in 1986, the Ph.D. degree in Automated Control from the Kiev Institute of Cybernetics, Kiev, Ukraine, in 1991, and the Dr.Sc. degree in Telecommunications from the Odessa National Academy of Telecommunications, Odessa, Ukraine, in 2006. He is a Professor of Information Technology at Odessa State Environmental University, Ukraine since 2019. He developed the analysis of infinite Petri nets with regular structure, the decomposition of Petri nets in clans, generalized neighborhood for cellular automata, and the method of synthesis of fuzzy logic function
given by tables. He developed Opera-Topaz software for manufacture operative planning and control; a new stack of networking protocols E6 and its implementation within Linux kernel; Petri net analysis software http://daze.ho.ua.

Date: 16.10.2020

Time: 3:00 PM CEST

Title: Delay Compensation in Control Systems

Speaker: Professor Michael Malisoff (Department of Mathematics, Lousiana State University, Baton Rouge, LA)

Abstract: Many control systems are subject to time delays. For instance, input delays may be caused by time-consuming information gathering, or gestation delays in biological processes. One approach to solving control problems under input delays involves solving the problems with the delays set to zero, and then computing upper bounds on the input delays that the systems can tolerate while still realizing the control objective. This is often done by finding Lyapunov-Krasovskii functions. For longer delays, the reduction model approach is often used but can lead to implementation challenges because of the presence of distributed terms in the control. A third approach to delay compensation involves sequential predictors, which can compensate for arbitrarily long input delays using stacks of differential equations instead of distributed terms. This talk will review recent developments in this area, and is based in part on the speaker’s joint work with Miroslav Krstic, Frederic Mazenc, Fumin Zhang, and several students.

About the speaker: Michael Malisoff earned his Ph.D. in Mathematics at Rutgers University in New Brunswick, NJ in 2000. He received the First Place Student Best Paper Award at the 1999 IEEE Conference on Decision and Control. In 2001, he joined the professorial faculty in the Department of Mathematics at Louisiana State University in Baton Rouge, LA, where he holds the Roy P. Daniels Professorship # 3 in the College of Science. His research is on systems and control, with an emphasis on engineering applications. He is an associate editor for Asian Journal of Control, European Journal of Control, Discrete and Continuous Dynamical Systems Series B, and SIAM Journal on Control and Optimization.

Date: 11.09.2020

Time: 3:00 PM CEST

Title: Modelling and Approximation in Complex Networked Systems

Speaker: Dr. Xiaodong Cheng (Department of Electrical Engineering, Eindhoven University of Technology, The Netherlands)

Abstract: Complex networked systems are becoming ever more prevalent in our society. The term ‘complex’ refers to large-scale topological features of the interactions as well as high-dimensional dynamics from different physical domains. The overwhelming complexity of these systems poses significant challenges in the systems and control domain of how to effectively and efficiently analyze and control these systems. In this talk, I will briefly introduce my research on scalable modeling and complexity reduction in dynamic networked systems. The first part considers the identifiability problem in complex networks, which aims to allocate external excitation signals such that all the dynamics in a network can be identified from data. The second part is focused on model-order reduction of structured networked systems that is to reduce the dimension of a complex network system while retaining all the salient structures and dynamics in the network avoiding unnecessary redundancy.


Date: 14.08.2020

Time: 3:00 PM CEST

Title: Shared Control Between Pilots and Autopilots: Illustration of a Cyber-Physical Human System

Speaker: Emre Eraslan (Systems Laboratory, Department of Mechanical Engineering, Bilkent University, Turkey)

Abstract: The control when two distinct decision-makers, a human operator and an advanced automation working together, face severe uncertainties and anomalies is a challenging problem. We focus on shared control architectures (SCAs) that allow an advantageous combination of their abilities and provide a desired resilient performance. One of the major challenges with two decision-makers in the loop is bumpy transfer when control responsibility switches between them. We propose the use of a common metric that enables a smooth, bumpless transition when severe anomalies occur. This common metric is termed Capacity for Maneuver (CfM), that is rooted in human behavior and can be identified in control systems as the actuator’s proximity to its limits of saturation. Two different SCAs are presented, both of which use CfM, and describe how human-experts and automation can participate in a shared control action and recover gracefully from anomalous situations. Both of the SCAs are validated using human-in-the-loop experiments. The experimental results show that in the context of flight control, these SCAs result in a bumpless, resilient performance.

Date: 17.07.2020

Time: 3:00 PM CEST

Title: Adaptive control allocation for constrained systems

Speaker: Shahabaldin Tohidi (Systems Laboratory, Department of Mechanical Engineering, Bilkent University, Turkey)

Abstract: Control allocation is the method of distributing control signals among redundant actuators. In the presence of actuator uncertainty, most existing control allocation strategies require estimation methods and/or excessive assumptions which might be hard to satisfy in practice. The proposed adaptive control allocation method does not require uncertainty estimation and/or persistency of excitation assumption. Actuator constraints are also respected by employing the projection algorithm. A human-in-the-loop stability analysis, in the presence of the proposed control allocation method, implies proper stability properties. In addition, a modified version of this method can be applied for pilot induced oscillation (PIO) mitigation in uncertain over-actuated systems.

Date: 26.06.2020

Time: 2:00 PM CEST

Title: Finite-time Estimation for Time Varying Systems with Delay

Speaker: Dr. Saeed Ahmed

Abstract: Constructing asymptotic observers for engineering systems is an important topic that is motivated by the difficulty of measuring state variables of systems. However, less attention has been paid to constructing finite-time observers, whose objective is to find values for states of the system after a predetermined finite time. Such a problem is important in engineering processes with deadlines and solving it can make it possible to design output feedback stabilizing controls. Moreover, measurement delays are present in many practical applications, such as chemical processes, aerodynamics, and communication networks, and they are time-varying. Therefore, the problem of finite-time estimation of systems with a time-varying delay is strongly motivated. The main aim of this talk is to present the design of finite-time observers for time-varying systems in the presence of a time-varying delay.

Date: 12.06.2020

Time: 2:00 PM CEST

Title: Self-triggered H-infinite control for Markov jump system

Speaker: Haiying Wan (Polytechnical University of Milano)

Abstract: Given the rapid development related to networked cyber-physical systems, new challenges arise in the context of systems with limited communication/computation bandwidth and/or limited energy resources in general. As one of the few aperiodic control strategies, self-triggered control can truly balance the usage of computational/communication resources on the one hand and control performance on the other. This talk will report recent work on self-triggered H-infinity control of Markov jump systems (MJSs). A resource-aware self-triggering scheme is proposed for MJSs to fulfill both disturbance rejection and computational resources saving goals. Besides, considering the finite frequency domain characteristics of the disturbance, the issue of a multi-frequency controller design based on the self-triggered strategy for MJSs is addressed.

Date: 15.05.2020

Time: 2:00 PM CEST

Title: Optimal Scheduling and Model Predictive Control for Trajectory Planning of Cooperative Robot Manipulators

Speaker: Dipl.-Ing. Argtim Tika

Abstract: The use of cooperating robots on existing assembly or packing lines relies on balancing the robots' workload and ensuring collision-free trajectory planning and execution. In this talk, we present a hierarchical control architecture with two-layer optimization-based control policies involving task scheduling in the top layer and path planning in the bottom one. For task allocation, a distance minimization algorithm is used, leading to an integer optimization problem with linear constraints and a bilinear cost function. For the trajectory planning, MPC-based methods are considered, which can be realized as a centralized architecture common to both robots, or as a distributed architecture where each robot is considered separately, as a local system.

Regelungstechnisches Seminar

das KL-Seminar der Regelungstechnik, wobei interne und externe Vortragende in regelmäßigen monatlichen Abständen eigene aktuelle Forschungsthemen zur Methodik und Anwendungen der Regelungs- und Systemtheorie vorstellen.

Interessierte Forschungsassistenten, Doktoranden, Dozenten und Professoren sind herzlich zur Teilnahme eingeladen. Das Seminar findet am ersten Dienstag des Monats statt. 

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