| 1. |
- Balluchi, A., et al.
(författare)
-
Hybrid control of networked embedded systems
- 2005
-
Ingår i: European Journal of Control. - : LAVOISIER. - 0947-3580 .- 1435-5671. ; 11:4-5, s. 478-508
-
Tidskriftsartikel (refereegranskat)abstract
- Hybrid systems that involve the interaction of continuous and discrete dynamics have been an active area of research for a number of years. In this paper, we start by briefly surveying the main theoretical control problems that have been treated in the hybrid systems setting and classify them into stabilization, optimal control and language specification problems. We then provide an overview of recent developments in four of the most prominent areas where these hybrid control methods have found application: control of power systems, industrial process control, design of automotive electronics and communication networks.
|
|
| 2. |
- Falkeborn, Rikard, et al.
(författare)
-
A Decomposition Algorithm for KYP-SDPs
- 2012
-
Ingår i: European Journal of Control. - : Hermes Science Publications. - 0947-3580 .- 1435-5671. ; 18:3, s. 249-256
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, a structure exploiting algorithm for semidefinite programs derived from the Kalman–Yakubovich– Popov lemma, where some of the constraints appear as complicating constraints is presented. A decomposition algorithm is proposed, where the structure of the problem can be utilized. In a numerical example, where a controller that minimizes the sum of the H2-norm and the H∞-norm is designed, the algorithm is shown to be faster than SeDuMi and the special purpose solver KYPD.
|
|
| 3. |
- Gustafsson, Thomas
(författare)
-
On the design and implementation of a rotary crane controller
- 1996
-
Ingår i: European Journal of Control. - 0947-3580 .- 1435-5671. ; 2:3, s. 166-175
-
Tidskriftsartikel (refereegranskat)abstract
- This paper deals with the feedback control of a rotary crane. The goal is to design a control system that assists the operator to move the cargo without oscillations and correctly align the cargo at the final position. This is accomplished with a weakly coupled pair of state feedback controllers with a nonlinear compensator. The controller has been implemented and tested on a real crane.
|
|
| 4. |
- Hjalmarsson, Håkan, et al.
(författare)
-
Model-free Tuning of a Robust Regulator for a Flexible Transmission System
- 1995
-
Ingår i: European Journal of Control. - 0947-3580 .- 1435-5671. ; 1:2, s. 148-156
-
Tidskriftsartikel (refereegranskat)abstract
- Recently, a data-driven model-free iterative control design method has been proposed [Hjalmarsson et al., Proc. 33rd IEEE CDC, Orlando, FL, 1994, 1735–1740]. This design method works directly with closed loop data from the plant and iteratively improves the pelformance. This contribution reports a simulation study of this method when applied to a flexible transmission system. The system is characterised by load dependent dynamics and certain performance specifications have to be satisfied for three different load cases. These specifications cannot be translated into a specific control criterion a priori. However, by adaptively changing the design criterion it is shown that it is possible to tune the criterion so as to eventually obtain the desired closed loop performance for all three load cases with the same controller. The new concepts of synthetic noise and time delays are shown to be valuable tools when tuning the criterion.
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Panteley, Elena, et al.
(författare)
-
Global Uniform Asymptotic Stability of Cascaded Nonlinear Non-Autonomous Systems
- 1999
-
Ingår i: European Journal of Control. - 0947-3580 .- 1435-5671. ; 5:1, s. 107-115
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we deal with the stability analysis problem of cascaded non-autonomous non-linear systems. In particular, we answer to the following questions: (i) What happens with the solutions of a time-varying non-linear system which is globally uniformly stable (GUS), when it is perturbed by the output of a globally exponentially stable (GES) system, in particular, when both systems form a cascade? (ii) If a time-varying non-linear system is globally uniformly asymptotically stable (GUAS), is this stability properly preserved when it is perturbed by an exponentially decaying input? Our proofs are based on a standard ‘delta-epsilon’ Lyapunov analysis. Finally, we show the utility of our results by applying our theorems to the problem of stabilisation of a turbo-charged diesel engine.
|
|
| 9. |
|
|
| 10. |
- Alanwar, Amr, et al.
(författare)
-
Privacy-preserving set-based estimation using partially homomorphic encryption
- 2023
-
Ingår i: European Journal of Control. - : Elsevier BV. - 0947-3580 .- 1435-5671. ; 71, s. 100786-
-
Tidskriftsartikel (refereegranskat)abstract
- The set-based estimation has gained a lot of attention due to its ability to guarantee state enclosures for safety-critical systems. However, collecting measurements from distributed sensors often requires out-sourcing the set-based operations to an aggregator node, raising many privacy concerns. To address this problem, we present set-based estimation protocols using partially homomorphic encryption that pre-serve the privacy of the measurements and sets bounding the estimates. We consider a linear discrete-time dynamical system with bounded modeling and measurement uncertainties. Sets are represented by zonotopes and constrained zonotopes as they can compactly represent high-dimensional sets and are closed under linear maps and Minkowski addition. By selectively encrypting parameters of the set repre-sentations, we establish the notion of encrypted sets and intersect sets in the encrypted domain, which enables guaranteed state estimation while ensuring privacy. In particular, we show that our protocols achieve computational privacy using the cryptographic notion of computational indistinguishability. We demonstrate the efficiency of our approach by localizing a real mobile quadcopter using ultra-wideband wireless devices.
|
|
| 11. |
- Alanwar, Amr, et al.
(författare)
-
Robust data-driven predictive control using reachability analysis
- 2022
-
Ingår i: European Journal of Control. - : Elsevier BV. - 0947-3580 .- 1435-5671. ; 68
-
Tidskriftsartikel (refereegranskat)abstract
- We present a robust data-driven control scheme for an unknown linear system model with bounded process and measurement noise. Instead of depending on a system model in traditional predictive con-trol, a controller utilizing data-driven reachable regions is proposed. The data-driven reachable regions are based on a matrix zonotope recursion and are computed based on only noisy input-output data of a trajectory of the system. We assume that measurement and process noise are contained in bounded sets. While we assume knowledge of these bounds, no knowledge about the statistical properties of the noise is assumed. In the noise-free case, we prove that the presented purely data-driven control scheme results in an equivalent closed-loop behavior to a nominal model predictive control scheme. In the case of measurement and process noise, our proposed scheme guarantees robust constraint satisfaction, which is essential in safety-critical applications. Numerical experiments show the effectiveness of the proposed data-driven controller in comparison to model-based control schemes.
|
|
| 12. |
- Aranovskiy, Stanislav, et al.
(författare)
-
Adaptive compensation of disturbances formed as sums of sinusoidal signals with application to an active vibration control benchmark
- 2013
-
Ingår i: European Journal of Control. - : Elsevier BV. - 0947-3580 .- 1435-5671. ; 19:4, s. 253-265
-
Tidskriftsartikel (refereegranskat)abstract
- An intuitive solution for the problem of adaptive attenuation of a disturbance formed as a finite sum of unknown sinusoidal signals is proposed for an internally stable discrete-time plant. The compensator is formed as a weighted sum of stable filters. An identification-based procedure for adaptive tuning of the coefficients is proposed for the case of unknown disturbance. We also propose a time-invariant compensator that provides perfect attenuation of a disturbance for the case when a model identification error is sufficiently small and disturbance frequencies are known. The technique is applied to a case study on a challenging benchmark example in the field of active vibration control. Attenuation of a disturbance formed as a sum of up to three sinusoidal signals with unknown/time-varying frequencies is demonstrated via simulation and experimental studies. (C) 2013 European Control Association. Published by Elsevier Ltd. All rights reserved.
|
|
| 13. |
- Bernardo, Carmela, 1993-, et al.
(författare)
-
Finite-time convergence of opinion dynamics in homogeneous asymmetric bounded confidence models
- 2022
-
Ingår i: European Journal of Control. - : ELSEVIER. - 0947-3580 .- 1435-5671. ; 68
-
Tidskriftsartikel (refereegranskat)abstract
- Bounded confidence opinion dynamics are dynamic networks in which agents are connected if their opinions are similar, and each agent updates her opinion as the average of the neighbors’ opinions. In homogeneous asymmetric Heglselmann–Krause (HK) models, all agents have the same confidence thresholds which could be different for the selection of upper and lower neighbors. This paper provides conditions for the convergence of the opinions to consensus and to clustering for this class of HK models. A new tighter bound on the time interval for reaching the steady state is also provided.
|
|
| 14. |
- Blanchini, Franco, et al.
(författare)
-
A convex programming approach to the inverse kinematics problem for manipulators under constraints
- 2017
-
Ingår i: European Journal of Control. - : Elsevier BV. - 0947-3580. ; 33, s. 11-23
-
Tidskriftsartikel (refereegranskat)abstract
- We propose a novel approach to the problem of inverse kinematics for possibly redundant planar manipulators. We show that, by considering the joints as point masses in a fictitious gravity field, and by adding proper constraints to take into account the length of the links, the kinematic inversion may be cast as a convex programming problem. Convex constraints in the decision variables (in particular, linear constraints in the workspace) are easily managed with the proposed approach. We also show how to exploit the idea for avoiding obstacles while tracking a reference end-effector trajectory and discuss how to extend the results to some kinds of non-planar manipulators. Simulation results are reported, showing the effectiveness of the approach.
|
|
| 15. |
- Boskos, Dimitris, et al.
(författare)
-
Decentralized abstractions for multi-agent systems under coupled constraints
- 2019
-
Ingår i: European Journal of Control. - : ELSEVIER SCIENCE BV. - 0947-3580 .- 1435-5671. ; 45, s. 1-16
-
Tidskriftsartikel (refereegranskat)abstract
- The goal of this paper is to define abstractions for multi-agent systems with feedback interconnection in their dynamics. In the proposed decentralized framework, we specify a finite or countable transition system for each agent which only takes into account the discrete positions of its neighbors. The dynamics of each agent consist of a feedback component which can guarantee certain system and network requirements and induces the coupled constraints, and additional input terms, which can be exploited for high level planning. In this work, we provide sufficient conditions for space and time discretizations which enable the abstraction of the system's behavior through a discrete transition system. Furthermore, these conditions include design parameters whose tuning provides the possibility for multiple transitions, and hence, the construction of transition systems with motion planning capabilities. Published by Elsevier Ltd. All rights reserved.
|
|
| 16. |
- Chaffey, Thomas, et al.
(författare)
-
Circuit analysis using monotone+skew splitting
- 2023
-
Ingår i: European Journal of Control. - 0947-3580.
-
Tidskriftsartikel (refereegranskat)abstract
- It is shown that the behavior of an m-port circuit of maximal monotone elements can be expressed as a zero of the sum of a maximal monotone operator containing the circuit elements, and a structured skew-symmetric linear operator representing the interconnection structure, together with a linear output transformation. The Condat–Vũ algorithm solves inclusion problems of this form, and may be used to solve for the periodic steady-state behavior, given a periodic excitation at each port, using an iteration in the space of periodic trajectories.
|
|
| 17. |
- Charitidou, Maria, et al.
(författare)
-
An MILP approach for persistent coverage tasks with multiple robots and performance guarantees
- 2022
-
Ingår i: European Journal of Control. - : Elsevier. - 0947-3580 .- 1435-5671. ; 64
-
Tidskriftsartikel (refereegranskat)abstract
- Multiple robots are increasingly being considered in a variety of tasks requiring continuous surveillance of a dynamic area, examples of which are environmental monitoring, and search and rescue missions. Motivated by these applications, in this paper we consider the multi-robot persistent coverage control problem over a grid environment. The goal is to ensure a desired lower bound on the coverage level of each cell in the grid, that is decreasing at a given rate for unoccupied cells. We consider a finite set of candidate poses for the agents and introduce a directed graph with nodes representing their admissible poses. We formulate a persistent coverage control problem as a MILP problem that aims to maximize the coverage level of the cells over a finite horizon. To solve the problem, we design a receding horizon scheme (RHS) and prove its recursive feasibility property by introducing a set of time-varying terminal constraints to the problem. These terminal constraints ensure that the agents are always able to terminate their plans in pre-determined closed trajectories. A two-step method is proposed for the construction of the closed trajectories, guaranteeing the satisfaction of the coverage level lower bound constraint, when the resulting closed trajectories are followed repeatedly. Due to the special structure of the problem, agents are able to visit every cell in the grid repeatedly within a worst-case visitation period. Finally, we provide a computational time analysis of the problem for different simulated scenarios and demonstrate the performance of the RHS problem by an illustrative example.
|
|
| 18. |
- Čičić, Mladen, 1991-, et al.
(författare)
-
Platoon-actuated variable area mainstream traffic control for bottleneck decongestion
- 2022
-
Ingår i: European Journal of Control. - : Elsevier BV. - 0947-3580 .- 1435-5671. ; 68
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper a platoon-actuated mainstream traffic control is proposed to decongest bottlenecks due to recurrent and nonrecurrent events. Indeed, differently from traditional mainstream control strategies, i.e., control strategies applied with fixed actuators, platoon-actuated control can be applied at any location on the freeway. In this work, the control actions to be communicated to the platoons, i.e., speed and configuration, are defined by means of a predictive control law based on traffic and platoon state detected in an area identified immediately upstream of the bottleneck. The main peculiarity of this scheme is that the size of the controlled area is dynamically adjusted based on the predicted congestion at the bottleneck. This approach keeps the control law computation burden low, while not sacrificing much control performance. Specifically, the number of platoons to be controlled and the time at which the platoons begin to be controlled depend on the size of the controlled area. Simulation results reported in the paper show the effectiveness of the proposed scheme, eliminating from 60% to 80% of the delay incurred from congestion compared with the uncontrolled case, depending on the level of traffic.
|
|
| 19. |
|
|
| 20. |
- Dhar, Abhishek, et al.
(författare)
-
Initial Excitation based Discrete-time Multi-Model Adaptive Online Identification
- 2022
-
Ingår i: European Journal of Control. - Amsterdam, Netherlands : Elsevier. - 0947-3580 .- 1435-5671. ; 68
-
Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a novel multi-model adaptive identification (MMAI) algorithm for discrete-time linear time invariant (LTI) uncertain systems with tunable performance. The uncertain plant parameter vector is assumed to belong to a known convex hull of a finite number of vertices; these vertices are considered as initial choice of vertices of an adaptive model parameter set. The estimated parameter, corresponding to the uncertain plant parameter, is computed at every instant as a convex combination of the model set vertices. To update the vertices of the adaptive model parameter set, a switched adaptive update law is proposed, along with a novel discrete-time initial excitation (IE) condition, which is imposed on the regressor signal. The proposed discrete-time IE condition is online verifiable and is milder than persistence of excitation (PE) condition, required for parameter convergence in classical adaptive estimation routines. The switched adaptive law guarantees exponential convergence of the vertices of the model set as well as the estimated parameter, to the true plant parameter, provided the regressor signal satisfies the IE condition. The properties of the designed MMAI strategy are validated through suitable simulation examples.
|
|
| 21. |
- Erdem, Ilker, 1987, et al.
(författare)
-
Feedforward control for oscillatory signal tracking using Hilbert transform
- 2019
-
Ingår i: European Journal of Control. - : Elsevier BV. - 0947-3580. ; 50, s. 41-50
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents feedforward control for oscillatory signal tracking using Hilbert transform. The proposed controller utilizes Hilbert transform and analysis techniques to determine the signal's amplitude, frequency, and phase. By using the frequency response of the linear time-invariant process model, an amplified and phase-shifted feedforward signal is reconstructed. The proposed controller also analyzes the system response to determine the differences from the model to modify the feedforward signal. Simulation experiments with multicomponent stationary, amplitude-, and frequency-modulated signals are also conducted. The results show that using an amplified and phase-shifted signal determined by Hilbert analysis can enable an effective tracking performance.
|
|
| 22. |
- Farjadnia, Mahsa, et al.
(författare)
-
Robust data-driven predictive control of unknown nonlinear systems using reachability analysis
- 2023
-
Ingår i: European Journal of Control. - : Elsevier BV. - 0947-3580.
-
Tidskriftsartikel (refereegranskat)abstract
- This work proposes a robust data-driven predictive control approach for unknown nonlinear systems in the presence of bounded process and measurement noise. Data-driven reachable sets are employed for the controller design instead of using an explicit nonlinear system model. Although the process and measurement noise are bounded, the statistical properties of the noise are not required to be known. By using the past noisy input-output data in the learning phase, we propose a novel method to over-approximate exact reachable sets of an unknown nonlinear system. Then, we propose a data-driven predictive control approach to compute safe and robust control policies from noisy online data. The constraints are guaranteed in the control phase with robust safety margins by effectively using the predicted output reachable set obtained in the learning phase. Finally, a numerical example validates the efficacy of the proposed approach and demonstrates comparable performance with a model-based predictive control approach.
|
|
| 23. |
- Freidovich, Leonid, et al.
(författare)
-
Discussion on: ``Robustness of PID-controlled manipulators vis-a-vis actuator dynamics and external disturbances''
- 2007
-
Ingår i: European Journal of Control. - 0947-3580 .- 1435-5671. ; 13:6, s. 755-759
-
Tidskriftsartikel (refereegranskat)abstract
- The paper by Chaillet, Loría, and Kelly is devoted to study robustness of mechanical systems controlled by proportional integral-differential (PID) regulators. These control strategies are classical and are the most frequently used in industrial applications of robotic manipulators despite various other available techniques. There is a number of results on properties of PID-controlled mechanical systems, see references in the paper and [1,2,5–7,11–13] to mention a few.
|
|
| 24. |
- García-Mañas, Francisco, et al.
(författare)
-
A practical solution for multivariable control of temperature and humidity in greenhouses
- 2024
-
Ingår i: European Journal of Control. - 0947-3580. ; 77
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a simple and effective control solution to regulate temperature and humidity inside a greenhouse, which are the main climatic variables affecting crop growth and health. A multivariable control strategy with inverted decoupling is proposed in two schemes. The nighttime control scheme uses heating and dehumidification, and the daytime control scheme uses natural ventilation, dehumidification, and humidification. A system identification methodology is used to obtain low-order linear models from data measured in a greenhouse. This simplifies the design of proportional–integral (PI) controllers and allows the use of well-known control techniques. For instance, anti-windup is used to deal with the saturation of the actuators and for a bumpless transfer mechanism to switch between the nighttime and the daytime control schemes. Setpoint weighting is used for the humidity controllers to attenuate undesired effects on the temperature control loop when the humidity setpoint is changed. Furthermore, split range control is used for the first time to control humidity by combining a heat-pump dehumidifier and a fogging system. The control solution presented in this work allows the integral absolute error to be reduced, on average, by 88.5% for the interactions affecting the temperature control loop, and by 85.6% for the humidity control loop, compared to decentralized PI control. The control schemes have been tested in simulation with real disturbance data from a Mediterranean greenhouse and in preliminary form in a real facility to conclude that the proposed multivariable control strategy could be effective in decoupling the temperature and the humidity control loops.
|
|
| 25. |
- Garin, Federica, et al.
(författare)
-
Strong structural input and state observability of linear time-invariant systems : Graphical conditions and algorithms
- 2021
-
Ingår i: European Journal of Control. - : ELSEVIER. - 0947-3580 .- 1435-5671. ; 58, s. 27-42
-
Tidskriftsartikel (refereegranskat)abstract
- The paper studies input and state observability (ISO) of discrete-time linear time-invariant network systems whose dynamics are affected by unknown inputs. More precisely, we aim at reconstructing the initial state and the sequence of unknown inputs from the system outputs, and we will use the term ISO when the input reconstruction is possible with delay one, namely the inputs up to time k - 1 and the states up to time k can be obtained from the outputs up to time k, while the term unconstrained ISO will refer to the case where there is some arbitrary delay in the input reconstruction. We focus on the problem of s-structural ISO (resp. s-structural unconstrained ISO) wherein the objective is to find conditions such that for all system matrices that carry the same network structure, the resulting system is ISO (resp. unconstrained ISO). We provide first a graphical characterization for s-structural unconstrained ISO, and subsequently, sufficient conditions and necessary conditions for s-structural ISO. For the latter, under the assumption of zero feedthrough, these conditions coincide and characterise ISO. The conditions presented are in terms of existence of suitable uniquely restricted matchings in bipartite graphs associated with the structured system. In order to test these conditions, we present polynomial-time algorithms. Finally, we discuss an equivalent reformulation of the main conditions in terms of coloring algorithms as in the literature of zero forcing sets.
|
|
| 26. |
- Hjalmarsson, Håkan, 1962-
(författare)
-
System Identification of Complex and Structured Systems
- 2009
-
Ingår i: European Journal of Control. - 0947-3580 .- 1435-5671. ; 15:3-4, s. 275-310
-
Tidskriftsartikel (refereegranskat)abstract
- A key issue in system identification is how to cope with high system complexity. In this contribution WE stress the importance of taking the application into account in order to cope with this issue. We define the concept "cost of complexity" which is a measure of the minimum required experimental effort (e.g., used input energy) as a function of the system complexity, the noise properties, and the amount, and desired quality, of the system information to be extracted from the data. This measure gives the user a handle on the tradeoffs that must be considered when performing identification with a fixed experimental "budget". Our analysis is based on the observation that the identification objective is to guarantee that the estimated model ends up within a pre-specified "level set" of the application objective. This geometric notion leads to a number of useful insights: Experiments should reveal system properties important for the application but may also conceal irrelevant properties. The latter, dual, objective can be explored to simplify model structure selection and model error assessment issues. We also discuss practical issues related to computation and implementation of optimal experiment designs. Finally, we illustrate some fundamental limitations that arise in identification of structured systems. This topic has bearings on identification in networked and decentralized systems.
|
|
| 27. |
|
|
| 28. |
- Kragelund, Martin, et al.
(författare)
-
Profit Maximization of a Power Plant
- 2012
-
Ingår i: European Journal of Control. - 0947-3580 .- 1435-5671. ; 18:1, s. 38-54
-
Tidskriftsartikel (refereegranskat)abstract
- This paper addresses the problem of profit maximization of a power plant by utilizing three different fuel systems in an optimal manner Pontryagin's maximum principle is used to derive properties of the optimal control strategy. These properties give rise to a switching function. Subsequently, certain heuristics are introduced and used in combination with discrete optimization to obtain an initial trajectory of the switching function. An iterative procedure is proposed, which uses the initial trajectory for the computation of the optimal control strategy. The control strategy derived is a combination of a state feedback and time-varying feedforward term. Its performance is tested against input noise.
|
|
| 29. |
|
|
| 30. |
- Larsson, Christian A., et al.
(författare)
-
An application-oriented approach to dual control with excitation for closed-loop identification
- 2016
-
Ingår i: European Journal of Control. - : Elsevier. - 0947-3580 .- 1435-5671. ; 29, s. 1-16
-
Tidskriftsartikel (refereegranskat)abstract
- Identification of systems operating in closed loop is an important problem in industrial applications, where model-based control is used to an increasing extent. For model-based controllers, plant changes over time eventually result in a mismatch between the dynamics of any initial model in the controller and the actual plant dynamics. When the mismatch becomes too large, control performance suffers and it becomes necessary to re-identify the plant to restore performance. Often the available data are not informative enough when the identification is performed in closed loop and extra excitation needs to be injected. This paper considers the problem of generating such excitation with the least possible disruption to the normal operations of the plant. The methods explicitly take time domain constraints into account. The formulation leads to optimal control problems which are in general very difficult optimization problems. Computationally tractable solutions based on Markov decision processes and model predictive control are presented. The performance of the suggested algorithms is illustrated in two simulation examples comparing the novel methods and algorithms available in the literature.
|
|
| 31. |
- Liang, Kuo-Yun, et al.
(författare)
-
Networked control challenges in collaborative road freight transport
- 2016
-
Ingår i: European Journal of Control. - : European Control Association. - 0947-3580 .- 1435-5671. ; 30, s. 2-14
-
Tidskriftsartikel (refereegranskat)abstract
- Freight transport is of major importance for the European economy and is growing thanks to increasing global trade. About three quarters of inland freight transport in the European Union is on roads. It has the potential to go through a dramatic change over the next decades thanks to the recent development of technologies such as wireless communication, cloud computing, sensor devices, and vehicle electronics. They enable a new integrated goods transport system based on optimized logistics, real-time traffic information, vehicular communications, collaborative driving, and autonomous vehicles. In this paper, we discuss challenges in creating a more efficient and sustainable goods road transportation system and how some of them can be tackled with a networked control approach. In particular, we discuss a method to improve the efficiency of the transportation system by minimizing the number of empty transports needed to fulfill the assignments on a given road network. Assignments with overlapping route segments might lead to further improvements, as the formation of vehicle platoons yields reduced fuel consumption. For realistic scenarios, it is shown that such collaboration opportunities arise already with relatively few vehicles. The fuel-efficient formation and control of platoons is also discussed. Some of the presented methods have been tested on real vehicles in traffic. The paper shows experimental results on automatic formation of vehicle platoons on a Swedish highway. The influence of traffic density on the merge maneuver is illustrated. The results indicate that platoon coordination could be improved by support from appropriate traffic monitoring technologies.
|
|
| 32. |
- Ljung, Lennart, 1946-
(författare)
-
Estimating Linear Time-Invariant Models of Nonlinear Time-Varying Systems
- 2001
-
Ingår i: European Journal of Control. - Linköping : Elsevier BV. - 0947-3580 .- 1435-5671. ; 7:2-3, s. 203-219
-
Tidskriftsartikel (refereegranskat)abstract
- The standard machinery for system identification of linear time-invariant (LTI) models delivers a nominal model and a confidence (uncertainty) region around it, based on (second order moment) residual analysis and covariance estimation. In most cases this gives an uncertainty region that tends to zero as more and more data become available, even if the true system is nonlinear and/or time-varying. In this paper, the reasons for this are displayed, and a characterization of the limit LTI model is gh,en under quite general conditions. Various ways are discussed, and tested, to obtain a more realistic limiting model, with uncertainty. These should reflect the distance to the true possibly nonlinear, time-varying system, and also form a reliable basis for robust LTI control design.
|
|
| 33. |
- Ljung, Lennart, 1946-, et al.
(författare)
-
Four Encounters with System Identification
- 2011
-
Ingår i: European Journal of Control. - : Hermes Science Publications. - 0947-3580 .- 1435-5671. ; 17:5-6, s. 449-471
-
Tidskriftsartikel (refereegranskat)abstract
- Model-based engineering becomes more and more important in industrial practice. System identification is a vital technology for producing the necessary models, and has been an active area of research and applications in the automatic control community during half a century. At the same time, increasing demands require the area to constantly develop and sharpen its tools. This paper deals with how system identification does that by amalgamating concepts, features and methods from other fields. It describes encounters with four areas in systems theory and engineering: Networked Systems, Particle Filtering Techniques, Sparsity and Compressed Sensing, and Machine Learning. The impacts on System Identification methodology by these encounters are described and illustrated.
|
|
| 34. |
- Ljung, Lennart, 1946-, et al.
(författare)
-
Robust Control of Identified Models with Mixed Parametric and Non-Parametric Uncertainties
- 2003
-
Ingår i: European Journal of Control. - : Elsevier BV. - 0947-3580 .- 1435-5671. ; 9:4, s. 373-380
-
Tidskriftsartikel (refereegranskat)abstract
- A framework for identification oriented robust controller design is developed. The model is identified from open-loop i/o-data and contains parametric uncertainties as well as an additive and norm-bounded error. The set of all robustly stabilising controllers, that additionally guarantee robust performance is characterised by a system of second order cones, which can be efficiently solved by interior point algorithms.
|
|
| 35. |
- Mascherpa, Michele, et al.
(författare)
-
Estimating pollution spread in water networks as a Schrödinger bridge problem with partial information
- 2023
-
Ingår i: European Journal of Control. - : Elsevier Ltd. - 0947-3580 .- 1435-5671.
-
Tidskriftsartikel (refereegranskat)abstract
- Incidents where water networks are contaminated with microorganisms or pollutants can result in a large number of infected or ill persons, and it is therefore important to quickly detect, localize and estimate the spread and source of the contamination. In many of today's water networks only limited measurements are available, but with the current internet of things trend the number of sensors is increasing and there is a need for methods that can utilize this information. Motivated by this fact, we address the problem of estimating the spread of pollution in a water network given measurements from a set of sensors. We model the water flow as a Markov chain, representing the system as a set of states where each state represents the amount of water in a specific part of the network, e.g., a pipe or a part of a pipe. Then we seek the most likely flow of the pollution given the expected water flow and the sensors observations. This is a large-scale optimization problem that can be formulated as a Schrödinger bridge problem with partial information, and we address this by exploiting the connection with the entropy regularized multimarginal optimal transport problem. The software EPANET is used to simulate the spread of pollution in the water network and will be used for testing the performance of the methodology. © 2023 The Author(s)
|
|
| 36. |
- McKelvey, Tomas
(författare)
-
Discussion on "On the Use of Minimal Parametrizations in Multivariable ARMAX Identification" by R.P. Guidorzi
- 1998
-
Ingår i: European Journal of Control. - 0947-3580 .- 1435-5671. ; 4, s. 93-98
-
Tidskriftsartikel (refereegranskat)abstract
- When performing practical identication the structural issue often cannot be neglected since the conditioning of the parameterization influence the convergence of the optimization. Solutions are to carefully monitor the conditioning of the associated LS problem or to use alternative parametrizations (minimal or non-minimal) which give better conditioning.
|
|
| 37. |
- Naha, Arunava, et al.
(författare)
-
Quickest physical watermarking-based detection of measurement replacement attacks in networked control systems
- 2023
-
Ingår i: European Journal of Control. - : Elsevier. - 0947-3580 .- 1435-5671. ; 71
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we propose and analyze an attack detection scheme for securing the physical layer of a networked control system (NCS) with a wireless sensor network against attacks where the adversary replaces the true observations with stationary false data. An independent and identically distributed watermarking signal is added to the optimal linear quadratic Gaussian (LQG) control inputs, and a cumulative sum (CUSUM) test is carried out using the joint distribution of the innovation signal and the watermarking signal for quickest attack detection. We derive the expressions of the supremum of the average detection delay (SADD) for a multi-input and multi-output (MIMO) system under the optimal and sub-optimal CUSUM tests. The SADD is asymptotically inversely proportional to the expected Kullback–Leibler divergence (KLD) under certain conditions. The expressions for the MIMO case are simplified for multi-input and single-output systems and explored further to distil design insights. We provide insights into the design of an optimal watermarking signal to maximize KLD for a given fixed increase in LQG control cost when there is no attack. Furthermore, we investigate how the attacker and the control system designer can accomplish their respective objectives by changing the relative power of the attack signal and the watermarking signal. Simulations and numerical studies are carried out to validate the theoretical results.
|
|
| 38. |
- Niazi, Muhammad Umar B., et al.
(författare)
-
Resilient set-based state estimation for linear time-invariant systems using zonotopes
- 2023
-
Ingår i: European Journal of Control. - : Elsevier BV. - 0947-3580 .- 1435-5671. ; 74
-
Tidskriftsartikel (refereegranskat)abstract
- This paper considers the problem of set-based state estimation for linear time-invariant (LTI) systems under time-varying sensor attacks. Provided that the LTI system is stable and observable via every single sensor and that at least one sensor is uncompromised, we guarantee that the true state is always contained in the estimated set. We use zonotopes to represent these sets for computational efficiency. However, we show that intelligently designed stealthy attacks may cause exponential growth in the algorithm's worst-case complexity. We present several strategies to handle this complexity issue and illustrate our resilient zonotope-based state estimation algorithm on a rotating target system.
|
|
| 39. |
- Nilsson, Magnus, 1978, et al.
(författare)
-
Adaptive Tracking for Linear Plants under Fixed Feedback
- 2012
-
Ingår i: European Journal of Control. - 0947-3580. ; 18:5, s. 411-421
-
Tidskriftsartikel (refereegranskat)abstract
- This paper examines a control structure with two degrees of freedom, where the feedback is kept fixed while the prefilter contains adaptive features. Proofs of stability and error convergence under idealized assumptions are provided for the discrete-time case using a proposed algorithm, where parameter projection into a "stable" parameter set is utilized. Under model-mismatch assumptions, conditions for boundedness are also listed. Two challenging control problems from the literature are then considered to illustrate a pragmatic design method. The resulting controllers are compared with alternative suggested structures for adaptive tracking with fixed feedback, and differences are pointed out through simple interpretations of the respective schemes.
|
|
| 40. |
- Parvini Ahmadi, Shervin, 1989-, et al.
(författare)
-
Distributed optimal control of nonlinear systems using a second-order augmented Lagrangian method
- 2023
-
Ingår i: European Journal of Control. - : Elsevier. - 0947-3580 .- 1435-5671. ; 70
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we propose a distributed second-order augmented Lagrangian method for distributed optimal control problems, which can be exploited for distributed model predictive control. We employ a primal-dual interior-point approach for the inner iteration of the augmented Lagrangian and distribute the corresponding computations using message passing over what is known as the clique tree of the problem. The algorithm converges to its centralized counterpart and it requires fewer communications between sub-systems as compared to algorithms such as the alternating direction method of multipliers. We illustrate the efficiency of the framework when applied to randomly generated interconnected sub-systems as well as to a vehicle platooning problem.
|
|
| 41. |
- Peni, T., et al.
(författare)
-
Induced L2 norm improvement by interpolating controllers for discrete time LPV systems
- 2009
-
Ingår i: European Journal of Control. - 0947-3580. ; 15:5, s. 1-15
-
Tidskriftsartikel (refereegranskat)abstract
- The paper shows an interpolation-based control solution asapossible technique to formulate the constrained H∞ control problem for discrete-time linear parameter varying (LPV) systems. The control policy is constructed by interpolating amongapriori designed, unconstrained, constant, state feedback controllers. Invariant set theory is used to introduce the measure of the domain of applicability. It is shown that the `trade-off' between the performance and the size of the domain of applicability can be significantly reduced by controller interpolation. Hence, the interpolation-based controller becomes applicable overamuch larger region than any other single state feedback. The proposed method gives stabilizing solution not only under hard constraints, but also allows the online modification of the induced L² norm from the generalized disturbance input to the predefined performance output. Moreover, the suggested method can be applied in real-time environment.
|
|
| 42. |
- Persson, Linnea, et al.
(författare)
-
An optimization algorithm based on forward recursion with applications to variable horizon MPC
- 2024
-
Ingår i: European Journal of Control. - : ELSEVIER. - 0947-3580 .- 1435-5671. ; 75
-
Tidskriftsartikel (refereegranskat)abstract
- We consider optimization algorithms designed for variable horizon model predictive control. Traditionally, such problems are considered intractable for real-time applications that require fast computations, as they need to solve multiple optimal control problems with varying horizons at each sampling instance. The main contribution is an algorithm that efficiently solves multiple optimal control problems with different prediction horizons in a recursive manner. This algorithm has been successfully implemented and integrated into the OSQP solver, resulting in a real-time controller that is both fast and reliable. To assess the effectiveness of the approach, we conducted evaluations in both a realistic simulation environment and on real hardware during outdoor flight experiments. Specifically, we focused on two distinct rendezvous maneuvers for autonomous landings of unmanned aerial vehicles. The results obtained from these evaluations further validate the practicality and efficacy of the proposed algorithm. (c) 2023 The Author(s). Published by Elsevier Ltd on behalf of European Control Association. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )
|
|
| 43. |
|
|
| 44. |
- Ramakrishna, Raksha, et al.
(författare)
-
Sequential Experiment Design for Parameter Estimation of Nonlinear Systems using a Neural Network Approximatort
- 2023
-
Ingår i: European Journal of Control. - : Elsevier BV. - 0947-3580 .- 1435-5671. ; 74
-
Tidskriftsartikel (refereegranskat)abstract
- We consider the problem of sequential parameter estimation of a nonlinear function under the Bayesian setting. The designer can choose inputs for a sequence of experiments to obtain an accurate estimate of the system parameters based on observed outputs, while complying with a constraint on the expected outputs of the system. We quantify the accuracy of the obtained estimate in terms of the pound 2 norm. We propose to solve the problem by casting it as the problem of minimizing the Bayesian Mean Square Error (BMSE) of the parameter estimate subject to a constraint on the expected deviation of the output from the desired target value. We develop a greedy policy to solve the problem in the sequential setting, and we characterize the solution structure based on analytical results for the Gaussian case. For a computationally tractable update of the posterior, we propose the use of a surrogate model combined with approximate Bayesian computation. We evaluate the proposed approach on the use case of smart road compaction, where the goal is to estimate asphalt parameters while reaching the desired compaction level, by choosing the value of the loading pressure. Simulation results on a synthetic road compaction dataset show the efficacy of the proposed solution scheme in both parameter estimation and effective compaction of the road.
|
|
| 45. |
- Rantzer, Anders
(författare)
-
15th European Control Conference, ECC16
- 2016
-
Ingår i: European Journal of Control. - : Elsevier BV. - 0947-3580. ; 30, s. 1-1
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
|
|
| 46. |
- Rantzer, Anders
(författare)
-
Scalable Control of Positive Systems
- 2015
-
Ingår i: European Journal of Control. - : Elsevier BV. - 1435-5671 .- 0947-3580. ; 24, s. 72-80
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Classical control theory does not scale well for large systems such as power networks, traffic networks and chemical reaction networks. However, many such applications in science and engineering can be efficiently modeled using the concept of positive systems and the nonlinear counterpart monotone systems. It is therefore of great interest to see how such models can be used for control. This paper demonstrates how positive systems can be exploited for analysis and design of large-scale control systems. Methods for synthesis of distributed controllers are developed based on linear Lyapunov functions and storage functions instead of quadratic ones. The main results are extended to frequency domain input–output models using the notion of positively dominated system. Applications to transportation networks and vehicle formations are provided.
|
|
| 47. |
- Rikos, Apostolos, et al.
(författare)
-
Distributed computation of exact average degree and network size in finite time under quantized communication
- 2023
-
Ingår i: European Journal of Control. - : Elsevier BV. - 0947-3580 .- 1435-5671. ; 74
-
Tidskriftsartikel (refereegranskat)abstract
- We consider the problems of computing the average degree and the size of a given network in a distributed fashion and under quantized communication. More specifically, we present two distributed algorithms, which rely on quantized operation (i.e., nodes process and transmit quantized messages) and are able to obtain the exact solutions in a finite number of steps. During the operation of our algorithms, each node can determine in a distributed manner whether convergence has been achieved and correspondingly terminate its operation. For terminating the operation of our algorithms, we assume a known bound for the network diameter. To the best of the authors' knowledge, these algorithms are the first to find exact solutions (i.e., with no error in the final result) under quantized communication. Note that our network size calculation algorithm is the first in the literature to calculate the exact size of a network in a finite number of steps without introducing a final error; in other algorithms, this error can be either due to quantization or asymptotic convergence. In our case, no error is introduced since the desired result is calculated in the form of a fraction involving an integer numerator and an integer denominator. We demonstrate the operation of our algorithms and their potential advantages through simulations.
|
|
| 48. |
|
|
| 49. |
- Shiriaev, Anton S., et al.
(författare)
-
A remark on Controlled Lagrangian approach
- 2013
-
Ingår i: European Journal of Control. - : Lavoisier. - 0947-3580 .- 1435-5671. ; 19:6, s. 438-444
-
Tidskriftsartikel (refereegranskat)abstract
- A new approach to trajectory planning for underactuated mechanical systems is presented and discussed based on analysis of feasible behaviors of a standard 2-DOF benchmark example - the cart-pendulum system. Following the Controlled Lagrangians approach of Bloch et al. (2000) [7], we present and re-establish known conditions and forms of feedback control laws for this example, which are leading to an equivalent completely integrable closed-loop Euler-Lagrange system; and then extend them. As shown, full integrability and, in particular, the presence of a linear in velocities first integral of dynamics plays the key role in an elegant new procedure for trajectory planning.
|
|
| 50. |
- Svärd, Carl, 1981-, et al.
(författare)
-
An Observer-Based Residual Generation Method for Linear Differential-Algebraic Equation Systems
- 2009
-
Ingår i: European Journal of Control. - 0947-3580 .- 1435-5671.
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Residual generation for linear differential-algebraic systems is considered. A new systematic method for observer-based residual generation is presented. The proposed design method places no restrictions on the system to be diagnosed. If the fault of interest can be detected in the system, the output from the design method is a residual generator in state-space form that is sensitive to the fault of interest. The method is iterative and relies only on constant matrix operations such as multiplications, null-space calculations and equivalence transformations, and thereby straightforward to implement. An illustrative numerical example is included, where the design method is applied to a nonobservable model of a robot manipulator.
|
|
