| 1. |
- Aguilar, Luis T., et al.
(författare)
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Generating oscillations in inertia wheel pendulum via two-relay controller
- 2012
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Ingår i: International Journal of Robust and Nonlinear Control. - Malden : Wiley-Blackwell. - 1049-8923 .- 1099-1239. ; 22:3, s. 318-330
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Tidskriftsartikel (refereegranskat)abstract
- The problem of generating oscillations of the inertia wheel pendulum is considered. We combine exact feedback linearization with two-relay controller, tuned using frequency-domain tools, such as computing the locus of a perturbed relay system. Explicit expressions for the parameters of the controller in terms of the desired frequency and amplitude are derived. Sufficient conditions for orbital asymptotic stability of the closed-loop system are obtained with the help of the Poincare map. Performance is validated via experiments. The approach can be easily applied for a minimum phase system, provided the behavior of the states of the zero dynamics is of no concern. Copyright (C) 2011 John Wiley & Sons, Ltd.
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| 2. |
- Bemporad, Alberto, et al.
(författare)
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Hybrid model predictive control based on wireless sensor feedback : An experimental study
- 2010
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Ingår i: International Journal of Robust and Nonlinear Control. - : Wiley. - 1049-8923 .- 1099-1239. ; 20:2, s. 209-225
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Tidskriftsartikel (refereegranskat)abstract
- Design and experimental validation of model predictive control (MPC) of a hybrid dynamical laboratory process with wireless sensors is presented. The laboratory process consists of four infrared lamps, controlled in pairs by two on/off switches, and of a transport belt, where moving parts equipped with wireless sensors are heated by the lamps. The process, which is motivated by heating processes in the plastic and printing industry, presents interesting hybrid dynamics. By approximating the stationary heat spatial distribution as a piecewise affine function of the position along the belt, the resulting plant model is a hybrid dynamical system. The control architecture is based on the reference governor approach: the process is actuated by a local controller, while a hybrid MPC algorithm running on a remote base station sends optimal belt velocity setpoints and lamp on/off commands over a wireless link, exploiting the sensor information received through the wireless network. A discrete-time hybrid model of the process is used for the hybrid MPC algorithm and for the state estimator. The physical modelling of the process and the hybrid MPC algorithm are presented in detail, together with the hardware and software architectures. The experimental results show that the presented theoretical framework is well suited for control of the new laboratory process, and that the process can be used as a prototype system for evaluating hybrid and networked control strategies.
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| 3. |
- Briat, Corentin
(författare)
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Robust stability and stabilization of uncertain linear positive systems via integral linear constraints : L-1-gain and L-infinity-gain characterization
- 2013
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Ingår i: International Journal of Robust and Nonlinear Control. - : Wiley. - 1049-8923 .- 1099-1239. ; 23:17, s. 1932-1954
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Tidskriftsartikel (refereegranskat)abstract
- Copositive linear Lyapunov functions are used along with dissipativity theory for stability analysis and control of uncertain linear positive systems. Unlike usual results on linear systems, linear supply rates are employed here for robustness and performance analysis using L-1-gain and L-gain. Robust stability analysis is performed using integral linear constraints for which several classes of uncertainties are discussed. The approach is then extended to robust stabilization and performance optimization. The obtained results are expressed in terms of robust linear programming problems that are equivalently turned into finite dimensional ones using Handelman's theorem. Several examples are provided for illustration.
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| 4. |
- Di Benedetto, Maria Domenica, et al.
(författare)
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Industrial control over wireless networks
- 2010
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Ingår i: International Journal of Robust and Nonlinear Control. - : JOHN WILEY & SONS LTD. - 1049-8923 .- 1099-1239. ; 20:2, s. 119-122
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Dong, J, et al.
(författare)
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Fault detection for LPV systems using model parameters that can be estimated via linear least squares
- 2014
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Ingår i: International Journal of Robust and Nonlinear Control. - : Wiley. - 1099-1239 .- 1049-8923. ; 24:14, s. 1989-1999
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a fault detection approach for discrete-time affine linear parameter varying systems with additive faults. A finite horizon input-output linear parameter varying model is used to obtain a linear in the model parameter regression residual form. The bias in the residual term vanishes because of quadratic stability of an underlying observer. The new methodology avoids projecting the residual onto a parity space, which in real time requires at least quadratic computational complexity. When neglecting the bias, the fault detection is carried out by an χ2 hypothesis test. Finally, the algorithm uses model parameters that can be identified prior to the on-line fault detection with linear least squares. A realtime experiment is carried out to demonstrate the viability of the proposed method.
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| 6. |
- Jacobsen, Elling W., et al.
(författare)
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Using dynamic perturbations to identify fragilities in biochemical networks
- 2010
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Ingår i: International Journal of Robust and Nonlinear Control. - : Wiley. - 1049-8923 .- 1099-1239. ; 20:9, s. 1027-1046
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Tidskriftsartikel (refereegranskat)abstract
- Biological functions at the cellular level result from interactions between genes, proteins and metabolites within complex biochemical reaction networks. Identifying specific and localized fragilities in such networks is important to understand the source of biological malfunctions, and to devise strategies for fighting disease states that have developed robustness. Herein we consider a method based on robust control theoretic concepts for identifying network fragilities. In particular, we consider adding static or dynamic perturbations to the network edges, i.e. the direct binary interactions within the network, and compute the smallest perturbation that induces a bifurcation, and hence a qualitative change, in the network function. The proposed method can also serve as a powerful modeling tool in that it can be used to identify parts of a model that require more detailed descriptions of the underlying processes. The method is demonstrated by application to models of sustained oscillations in the glycolytic pathway and bistability in the mitogen-activated protein kinase (MAPK) signal transduction.
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| 7. |
- Kee, Chew Yee, et al.
(författare)
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New results in robust functional state estimation using two sliding mode observers in cascade
- 2014
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Ingår i: International Journal of Robust and Nonlinear Control. - : Wiley-Blackwell. - 1049-8923 .- 1099-1239. ; 24:15, s. 2079-2097
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a functional observer scheme using two sliding mode observers in cascade. A coordinate transformation is performed on the system such that existing sliding mode observer theory can be directly applied to achieve functional state estimation. The necessary and sufficient existence conditions for the scheme (in terms of the original system matrices) are also investigated, and they are found to be less stringent than earlier work on functional state estimation using one sliding mode observer; this could have benefits in terms of cost and simplicity. A numerical example verifies the effectiveness of the scheme.
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| 8. |
- Kulcsár, Balázs Adam, 1975, et al.
(författare)
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Unknown input reconstruction for LPV systems
- 2010
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Ingår i: International Journal of Robust and Nonlinear Control. - 1099-1239 .- 1049-8923. ; 20:5, s. 579-595
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Tidskriftsartikel (refereegranskat)abstract
- Detection and invariant subspaces of unknown inputs' signals for linear parameter-varying systems are examined in the paper. For a class of nonlinear system like this, the effect of unmeasured signals in parameter-varying measurement equation at the plant output is investigated.The main contributions of the paper are the parameter-varying extension of the pseudo-actuation of the possible and generic unknown sensor signal and the proposition of parameter-dependent similarity transformation. The general parameter-varying measurement equation is casted into a parameter-independent form by the similarity transformation, if any. Moreover, it showed that the nonlinear state transformation does not modify the output subspace spanned by the equivalent pseudo-actuator directions.
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| 9. |
- Köroglu, Hakan, 1971
(författare)
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Observer-based linear parameter-varying control with guaranteed L2-gain and H2-type performance objectives
- 2014
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Ingår i: International Journal of Robust and Nonlinear Control. - : Wiley. - 1099-1239 .- 1049-8923. ; 24:14, s. 2000-2017
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Tidskriftsartikel (refereegranskat)abstract
- Synthesis of an observer-based linear parameter-varying controller is considered for a general linearparameter-varying plant. The parameter vector and its derivative are both assumed to take values in knownbounded domains, whereas only the parameter vector is assumed to be measurable during online operation.The synthesis problem is considered for L2-gain and H2-type performance objectives. Potentially conservativeparameter-dependent linear matrix inequality conditions are derived for the solvability of these twoproblems. To facilitate the reduction of conservatism, the conditions are expressed in a way to have bilineardependence on an arbitrary positive scalar. In addition to employing a suitable relaxation scheme to reducethese conditions into finitely many constraints, a line search hence needs to be performed over the positivescalar to obtain the best achievable performance with an observer-based controller. The online implementationof the observer-based controller is relatively simpler if compared with a controller of unrestrictedstructure. Moreover, the observer-based controller will have no dependence on the parameter derivativesirrespective of the choices of the design variables.
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| 10. |
- Liu, Kun, 1982-, et al.
(författare)
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Discrete-time Network-based Control under Schedulings and Actuator Constraints
- 2014
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Ingår i: International Journal of Robust and Nonlinear Control. - : Wiley. - 1049-8923 .- 1099-1239.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This paper is concerned with the solution bounds for discrete-time networked control systems via delay-dependent Lyapunov-Krasovskii methods.Solution bounds are widely used for systems with input saturation caused byactuator saturation or by the quantizers with saturation.The time-delay approach has been introduced recently for the stabilization of continuous-time networked control systems under the Round-Robin protocol in \cite{KunSCL12} and under a weighted Try-Once-Discard protocol in \cite{KunCDC12}, respectively.Actuator saturation has not been taken into account in \cite{KunCDC12} and \cite{KunSCL12}.In the present paper, for the first time the time-delay approach is extended to the stability analysis of the discrete-time networked control systems under both scheduling protocols and actuators saturation. The communication delays are allowed tobe larger than the sampling intervals.A novel Lyapunov-based method is presented for finding the domain of attraction.Polytopic uncertainties in the system model can be easily included in our analysis. The efficiency of the time-delay approach is illustrated on the example of a cart-pendulum system.
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| 11. |
- Meng, Ziyang, et al.
(författare)
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On distributed finite-time observer design and finite-time coordinated tracking of multiple double integrator systems via local interactions
- 2014
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Ingår i: International Journal of Robust and Nonlinear Control. - : Wiley. - 1049-8923 .- 1099-1239. ; 24:16, s. 2473-2489
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Tidskriftsartikel (refereegranskat)abstract
- This paper studies finite-time coordinated tracking problem for multiple double integrator systems with a time-varying leader's velocity and bounded external disturbances. We consider the dynamic feedback designs for two different cases. In the first case, the velocities of the followers and the leader are assumed to be unavailable, and the communication topology is assumed to be undirected and fixed. In the second case, the velocities of the followers and the leader are assumed to be available, and the communication topology is assumed to be directed and switching. Distributed finite-time observers are designed, respectively, to obtain the velocity information in the first case and the relative state information in the second case. The states of these observers are then used to design control inputs that achieve finite time robust coordinated tracking of multiple double integrator systems in the presence of bounded disturbances for these two cases. Simulation results are provided to validate the effectiveness of these theoretical results.
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| 12. |
- Rabi, Maben, et al.
(författare)
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Networked estimation under contention-based medium access
- 2010
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Ingår i: International Journal of Robust and Nonlinear Control. - : Wiley. - 1049-8923 .- 1099-1239. ; 20:2, s. 140-155
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Tidskriftsartikel (refereegranskat)abstract
- This paper studies networked estimation over a communication channel shared by a contention-based medium access protocol. A collection of N identical and physically decoupled scalar systems are sampled without sensor noise and transmitted over a common channel, using a contention-based medium access mechanism. We first carry out a calculation of the average distortion in estimation with irregular samples. Given the rate of packet generation at sensors, we characterize the traffic characteristics of the some contention-based MAC schemes. This lets us derive the statistics of inter-arrival times which in turn allows us to compute the packet loss rates and also the statistics of delay within a sample period. Using these results, we track the estimation performance as the sample generation rate and the number of contending nodes are varied. We provide a heuristic rule-of-thumb for choosing the sampling interval which minimizes the average distortion. By combining the network traffic characterization with that of the estimation performance, we show this rule performs pretty well. Carrying along the same lines, we are able to compute the scaling limits of estimation performance with respect to the number of contending nodes.
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| 13. |
- Segundo Sevilla, Felix Rafael, et al.
(författare)
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Fault-tolerant control design to enhance damping of inter-area oscillations in power grids
- 2013
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Ingår i: International Journal of Robust and Nonlinear Control. - : Wiley. - 1049-8923 .- 1099-1239. ; 24:8-9, s. 1304-1316
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, passive and active approaches for the design of fault-tolerant controllers (FTCs) are presented. The FTCs are used to improve the damping of inter-area oscillations in a power grid. The effectiveness of using a combination of local and remote (wide area) feedback signals is first demonstrated. The challenge is then to guarantee a minimum level of dynamic performance following a loss of remote signals. The designs are based on regional pole placement using linear matrix inequalities. First, a passive FTC is proposed. It is shown that the computation of the controller reduces to the solution of bilinear matrix inequalities. An iterative procedure is then used to design the controller. Next, as an alternative to active, time-varying controllers, one for each fault scenario, we propose an approach for the design of a ‘minimal switching’ FTC in which only one controller is designed, but where a simple switch is incorporated into the controller structure. A case study in a linear and nonlinear Nordic equivalent system is presented to show that the closed-loop response using a conventional control design could deteriorate the performance or even destabilize the system if the remote signals are lost and to demonstrate the effectiveness of the proposed FTC designs.
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| 14. |
- Wang, Xu, et al.
(författare)
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Synchronization in a network of identical discrete-time agents with uniform constant communication delay
- 2014
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Ingår i: International Journal of Robust and Nonlinear Control. - : Wiley. - 1049-8923 .- 1099-1239. ; 24:18, s. 3076-3091
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Tidskriftsartikel (refereegranskat)abstract
- This paper studies the synchronization problem for a network of identical discrete-time agents with unknown uniform constant communication delay. When the agents are non-introspective, the problem is solvable via a decentralized low-gain-based synchronization controller if the delay satisfies the proposed upper bound. When the agents are introspective, the synchronization problem can be solved with arbitrary bounded communication delay.
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| 15. |
- Wang, Xu, et al.
(författare)
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Synchronization in heterogeneous networks of discrete-time introspective right-invertible agents
- 2014
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Ingår i: International Journal of Robust and Nonlinear Control. - : Wiley. - 1049-8923 .- 1099-1239. ; 24:18, s. 3255-3281
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Tidskriftsartikel (refereegranskat)abstract
- This paper studies output synchronization problem, formation problem, and regulated synchronization problem for a heterogenous network of discrete-time introspective right-invertible agents. We first propose a decentralized control scheme to solve the output synchronization problem for a set of communication topologies. Moreover, if the synchronization trajectories are assumed to be bounded, a universal controller can be constructed for all communication topologies, which contain a directed spanning tree. The design can be applied to solve the formation problem with arbitrary formation vectors. In the regulated synchronization problem, we assume only the root receives information from exosystem. We then design a decentralized controller to solve the problem for a set of communication topologies.
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| 16. |
- Witrant, E., et al.
(författare)
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Wireless ventilation control for large-scale systems : The mining industrial case
- 2010
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Ingår i: International Journal of Robust and Nonlinear Control. - : Wiley. - 1049-8923 .- 1099-1239. ; 20:2, s. 226-251
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes a new industrial case on automation, for large-scale systems with high environmental impact: the mining ventilation control systems. Ventilation control is essential for the operation of a mine in terms of safety (CO and NO, regulation) and energy optimization. We first discuss a novel regulation architecture, highlighting the interest for a model-based control approach and the use of distributed sensing capabilities thanks to a wireless sensor network (WSN). We propose a new model for underground ventilation. The main components of the system dynamics are described with time-delays, transmission errors, energy losses and concentration profiles. Two different model-based control approaches, which can embody the complex dynamics of the system, are proposed. The first one resorts to a nonlinear model predictive control strategy (receding horizon) and aims to energy minimization, thanks to a continuous operation of the fans. The second one, based on a hybrid description of the model and fans operation, provides automatic verification of the wireless control thanks to abstraction techniques. These control strategies are compared with simulations, in terms of regulation efficiency, energy consumption and the need for computational capabilities. The industrial case description and control strategies open new vistas for the development of global system approaches that allow for the optimization of energy consumption of complex large-scale systems.
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| 17. |
- Yang, Tao, et al.
(författare)
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Output synchronization for heterogeneous networks of introspective right-invertible agents
- 2014
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Ingår i: International Journal of Robust and Nonlinear Control. - : Wiley. - 1049-8923 .- 1099-1239. ; 24:13, s. 1821-1844
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we consider the output synchronization problem for heterogeneous networks of right-invertible linear agents. We assume that all the agents are introspective, meaning that they have access to their own local measurements. Under this assumption, we then propose a decentralized control scheme for solving the output synchronization problem for a set of network topologies. The proposed scheme can also be applied to solve the output formation problem with arbitrary formation vectors. We also consider the regulation of output synchronization problem, where the output of each agent has to track an a priori specified reference trajectory, generated by an exosystem. In this case, we assume that the root agent has access to its own output relative to the reference trajectory.
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| 18. |
- Yang, Tao, et al.
(författare)
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Semi-global regulation of output synchronization for heterogeneous networks of non-introspective, invertible agents subject to actuator saturation
- 2014
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Ingår i: International Journal of Robust and Nonlinear Control. - : Wiley. - 1049-8923 .- 1099-1239. ; 24:3, s. 548-566
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we consider the semi-global regulation of output synchronization problem for heterogeneous networks of invertible linear agents subject to actuator saturation. That is, we regulate the output of each agent according to an a priori specified reference model. The network communication infrastructure provides each agent with a linear combination of its own output relative to that of neighboring agents, and it allows the agents to exchange information about their own internal observer estimates while some agents have access to their own outputs relative to the reference trajectory.
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