| 1. |
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| 2. |
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| 3. |
- Dabiri, Azita, 1984, et al.
(författare)
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Incident description in METANET model
- 2013
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Ingår i: 2nd National Conference in Transportation, October 2013, Gothenburg.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Dabiri, Azita, 1984, et al.
(författare)
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Incident parameter estimation
- 2013
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Ingår i: Proc. of European Control Conference ECC’13, July 17-19, Zurich, Switzerland.. - : IEEE. - 9783033039629 ; , s. 3518-3523
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Konferensbidrag (refereegranskat)abstract
- The paper proposes a sampled data based estimation methodology to reconstruct local incident parameter of the macroscopic Incident Traffic Flow (ITF) models. The key idea in ITF models is to dynamically relax the traffic mean speed to the traffic equilibrium one based of an time and space varying incident term. First, the analysis of incident corrupted traffic flow models, described as an in-homogeneous nonlinear Partial Differential Equation (PDE), is presented in continuous time. Second, space and time discretization techniques are applied to derive traffic management oriented ITF models. Online parameter estimation is suggested to capture the severity of incident throughout the proposed parameter, i.e. to estimate the incident parameter. Numerical example is carried out to show the viability of macroscopic incident parameter estimation technique using data obtained from a high-fidelity microscopic simulation.
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| 5. |
- Dabiri, Azita, 1984, et al.
(författare)
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Incident parameter scheduled freeway traffic control - A ramp meter approach
- 2014
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - : Elsevier BV. - 1474-6670. - 9783902823625 ; 19, s. 11338-11343
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Konferensbidrag (refereegranskat)abstract
- A novel model based local ramp metering method is presented in the paper by means of incident scheduled freeway traffic control solution. First, second order macroscopic freeway model is used with appropriate incident parametrization to describe eventual and unattended traffic variation caused by off-nominal traffic conditions (e.g. accidents). These traffic anomalies are captured by adequate model parameters, i.e. incident parameters that can be on-line estimated. The paper is motivated by incident scheduled ramp-meter solution to encounter real-time incident parameter information. The main idea is to use local freeway control solution triggered by available incident parameter values. The proposed approach is local in the sense of considering only non-coordinated ramp meter solution, first. Furthermore, we apply locally optimal (linearized) control solution to satisfy throughput maximization objective. The formal controller synthesis involves parameters to correct, compensate the effect of incidents. The proposed method is evaluated and compared to other existing approach by using simulation environment.
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| 6. |
- 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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| 7. |
- Kovacs, L., et al.
(författare)
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Robust servo control of a novel type 1 diabetic model
- 2011
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Ingår i: Optimal Control Applications and Methods. - : Wiley. - 1099-1514 .- 0143-2087. ; 32:2, s. 215-238
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Tidskriftsartikel (refereegranskat)abstract
- Robust servo control of a model-based biomedical application is presented in the article. The glucose-insulin control of type 1 diabetic patients is considered to be solved using the results of post-modern robust control principles. The paper uses a recently published glucose-insulin model and presents the transformation of the model to describe the dynamics of type 1 diabetes mellitus. The nonlinear plant is then linearized at a given steady state point. In order to characterize the uncertainty around the nominal model in frequency domain, a parametric nonlinear model sensitivity analysis is performed using gridding method. The aim of the paper is to underline the viability of the robust servo, linear mu-control algorithm tested in highly nonlinear closed-loop simulation environment. Using two degree-of-freedom robust controller, the structured singular value of the closed-loop is designed to fulfill the robust performance requirements and assure glucose level control. Glucose level tracking is ensured under simulated and realistic exogenous meal disturbances.
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| 8. |
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| 9. |
- Kulcsár, Balázs Adam, 1975, et al.
(författare)
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Impulse response parameter based internal model control for discrete-time LPV systems
- 2014
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Ingår i: 13th European Control Conference, ECC 2014, Strasbourg Convention and Exhibition Center, Place de Bordeaux, Strasbourg, France, 24-27 June 2014. - 9783952426913 ; , s. 424-429
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Konferensbidrag (refereegranskat)abstract
- This paper presents a novel impulse response parameter based solution for internal model control (IMC) within the linear parameter varying framework. First, based on a discrete-time state-space representation, a finite horizon vector autoregressive model with exogenous disturbance (VARX) is obtained to describe the I/O relationship of an affine LPV plant. In this paper, inversion of the VARX model w.r.t. control input directly leads to a IMC law where analytic solution can be derived for unconstrained and optimal reference tracking error minimization. When the bias term in the finite horizon I/O predictor is neglected, asymptotic properties of closed-loop IMC is analyzed. The VARX parameters of the I/O LPV model can be factorized into a scheduling dependent data matrix and a sequence of constant impulse response parameters (IRPs). The latter part can consistently be identified from data as a single least-squares problem. Without the need to build or identify an LPV state-space model, this methodology is able to address IMC tracking error minimization by using IRPs. The viability of the proposed method is numerically tested in simulation environment.
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| 10. |
- Kulcsár, Balázs Adam, 1975, et al.
(författare)
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Integrated robust control/fault diagnosis design for LPV systems under input constraints
- 2012
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Ingår i: European Workshop on Advanced Control and Diagnosis ACD’12.
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a joint controller and fault estimator design for continuous-time Linear Parameter Varying systems. In the presented problem statement, the structure of the modeling uncertainty couples the controller and fault estimator synthesis. Furthermore, as in most of the cases, control input actions are subjected to hard physical constraints, this paper aims at developing an integrated methodology where these bounds can explicitly be taken into considerations.
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| 11. |
- Kulcsár, Balázs Adam, 1975, et al.
(författare)
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On the similarity state transformation for Linear Parameter-Varying systems
- 2011
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 1474-6670. - 9783902661937 ; 18:PART 1, s. 4155-4160
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Konferensbidrag (refereegranskat)abstract
- Similarity state transformations between equivalent State-Space (SS) representations of discrete-time Linear Parameter-Varying (LPV) systems are investigated. Based on previous results, it is known that to characterize all equivalent LPV-SS representations, the state-transformation matrix must depend dynamically on the scheduling variable. However, preserving static dependence of a LPV-SS representation, i.e. characterizing all equivalent SS representation with static dependence, has primary importance both in control and identification. Therefore, first, the state transformation problem is investigated from an algebraic (behavior) point of view, then conditions are developed to guarantee preservation of the static dependence in similarity state transformations. Additional geometric interpretation of the obtained results, together with computational approach to synthesize state-transformations are also developed. An illustrative example is provided to demonstrate the validity of the obtained results.
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| 12. |
- Kulcsár, Balázs Adam, 1975, et al.
(författare)
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Robust cautious data driven control with guaranteed mean square stability
- 2010
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Ingår i: Proceedings of 49th IEEE Conference on Decision and Control, December 15-17, Atlanta, Georgia, USA, 2010. - 0191-2216. - 9781424477456 ; , s. 2276-2281
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Konferensbidrag (refereegranskat)abstract
- The paper presents a cautious and robust ap- proach for data driven control synthesis. It proposes to parame- terize a closed-loop LTI output predictor by Least Squares (LS) estimated and stochastically uncertain Markov parameters, completely characterizable by measured input and output (I/O) data. Direct embedding of I/O data, carrying uncertain Markov parameter information, into the robust infinite horizon controller design method does not only guarantee mean square stability of the closed-loop system under stochastic model uncertainties, but also reject the effect of disturbance term over a pre-defined performance output. Example shows the effectiveness of the elaborated method.
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| 13. |
- Kulcsár, Balázs Adam, 1975, et al.
(författare)
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Robust inversion based fault estimation for discrete-time LPV systems
- 2012
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Ingår i: IEEE Transactions on Automatic Control. - 0018-9286 .- 1558-2523. ; 57:6, s. 1581-1586
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Tidskriftsartikel (refereegranskat)abstract
- The article presents a state-space based Fault Diagnosis (FD) method for discrete-time, affine Linear Parameter Varying (LPV) systems. The goal of the technical note is to develop a robust and dynamic inversion based technique for systems with parameter varying representations when an additive, exogenous disturbance signal perturbs the system. After applying geometric concepts for explicit fault inversion, a robust strategy is proposed to attenuate the effect of the unknown disturbance input signal on the fault estimation error. The proposed robust observer is derived as a solution of off-line Linear Matrix Inequality (LMI) conditions. The technical note demonstrates the viability of the novel methodology through a numerical example.
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| 14. |
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| 15. |
- 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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| 16. |
- Luspay, T., et al.
(författare)
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Constrained Freeway Traffic Control via Linear Parameter Varying Paradigms
- 2012
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Ingår i: J. Mohammadpour and C.W. Scherer (eds.), Control of linear parameter varying systems with applications, Springer. - Boston, MA : Springer US. - 9781461418320 ; 9781461418337, s. 461-482
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- A novel freeway traffic control design framework is proposed in the chapter. The derivation is based on the parameter-dependent reformulation of the second-order macroscopic freeway model. Hard physical constraints are handled implicitly, by introducing additional scheduling parameter for controller saturation measure. The ramp metering problem is then formulated as an induced L2 norm minimization, where the effects of undesired traffic phenomena are attenuated on the network throughput. The solution of the resulting problem involves convex optimization methods subjected to Linear Matrix Inequalities. A numerical example is given to validate the parameter-dependent controller and evaluate its effectiveness under various traffic situations.
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| 17. |
- Luspay, T., et al.
(författare)
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Freeway ramp metering: an LPV set theoretical analysis
- 2011
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Ingår i: American Control Conference. - 0743-1619. - 9781457700804 ; , s. 733-738
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Konferensbidrag (refereegranskat)abstract
- The paper contributes to the set theoretic analysis of freeway traffic flow control by ramp metering.From the generic and discrete time non-linear second-order macroscopic dynamics of freeway, first, an equivalent, quasi Linear Parameter Varying (LPV) representation is derived by steady-state centering and factorization. Second, a polytopic LPV model form is obtained from the quasi reformulation of the non-linear problem statement. The latter polytopic LPV form is then used for the computation and analysis of distur- bance invariant sets. This framework is able to characterize constrained sets of states which can be reached by pure ramp metering control input signal respectively becomes invariant under the effect of other measured and unmeasured inputs.The application of disturbance invariant set theory clearly quantifies the set of states being invariant under the polytopic LPV dynamics and other physical constraints regardless to the open- and closed-loop nature of the system.The proposed idea is fully based on the analysis of the (transformed) non-linear macroscopic system and aims at filling the gap between the traffic modelling and quantitative freeway ramp metering.
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| 18. |
- Luspay, T., et al.
(författare)
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Linear Parameter Varying Identification of Freeway Traffic Models
- 2011
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Ingår i: IEEE Transactions on Control Systems Technology. - 1063-6536 .- 1558-0865. ; 19:1, s. 31-45
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Tidskriftsartikel (refereegranskat)abstract
- This paper deals with linear parameter varying (LPV) modeling and identification of a generic, second-order freeway traffic flow model. A non-conventional technique is proposed to transform the nonlinear freeway traffic flow model into a parameter-dependent form. The resulting exact LPV model is equivalent to the original nonlinear dynamics. Simplification of the nonlinear model gives rise to the introduction of an approximate LPV description. The application of parameter varying identification approaches are made possible by the transformation. Closed-loop predictor-based subspace identification for LPV systems (PBSID LPV) is applied to estimate the affine parameter matrices of the LPV freeway models developed. If the model structure of the original plant is assumed to be known, this paper shows a solution how to estimate LPV model parameters based on the identified model. Parameter-dependent models are identified and validated using real detector measurement data in order to emphasize the applicability of the kernel PBSID LPV methodology. Comparison with traditional nonlinear parametric identification, generally used in traffic identification, is also provided.
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| 19. |
- Luspay, T., et al.
(författare)
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Mean-square optimal control of Linear Parameter Varying systems
- 2013
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Ingår i: American Control Conference. - 0743-1619. - 9781479901777 ; , s. 6084 - 6089
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Konferensbidrag (refereegranskat)abstract
- The problem of designing parameter-dependent output feedback controllers by using inaccurate knowledge of the scheduling parameter is addressed in the paper. Discrete time Linear Parameter Varying (LPV) systems are considered with external scheduling variables corrupted by measurement noise. The paper investigates the optimal control of such LPV class in the quadratic mean-square sense. The solution of the controller design problem is obtained as a standard optimization problem subject to Linear Matrix Inequality (LMI) constraints. A comparative simulation example is given to illustrate the proposed methodology and underline the importance of embedding stochastic information in the LPV control design procedure.
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| 20. |
- Luspay, T., et al.
(författare)
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Parameter-dependent modeling of freeway traffic flow
- 2010
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Ingår i: Transportation Research, Part C: Emerging Technologies. - : Elsevier BV. - 0968-090X. ; 18:4, s. 471-488
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Tidskriftsartikel (refereegranskat)abstract
- In the paper a novel non-linear modeling formalism is suggested for freeway traffic flow. A second-order macroscopic model has been transformed into a Linear Parameter Varying (LPV) model. The paper proposes two LPV descriptions for traffic modeling: the first one covers completely the non-linear macroscopic dynamics, while the second one is an approximate description. Real test field topology and measurement data are used for validating the proposed modeling methodology. Simulation examples are given to compare real detector measurements, non-linear and the parameter-dependent responses.
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| 21. |
- Peni, T., et al.
(författare)
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Model recovery anti-windup control for linear discrete time systems with magnitude and rate saturation
- 2012
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Ingår i: American Control Conference. - : IEEE. - 0743-1619. - 9781457710957 ; , s. 1543-1548
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Konferensbidrag (refereegranskat)abstract
- The paper proposes a model recovery anti-windup (MRAW) scheme for linear time-invariant and discrete-time systems under magnitude and rate saturation. The method is a modified, discrete-time counterpart of the algorithm presented in [4]. As it is usual in the MRAW framework the AW compensator contains the exact copy of the plant in order that the ideal (unsaturated) behavior can be preserved in the states. The compensator is a controller that aims to push the plant towards this intended behavior. The design of this control action can be reduced to a construction of a stabilizing state feedback acting on the saturated plant. In [4] this feedback is a linear one, which is designed by convex optimization by enlarging the ellipsoidal approximation of the invariant domain. This paper presents a different, set-theoretic approach, which is based on the precise construction of the maximal control invariant set. The proposed control is a nonlinear one generated by point wise convex optimization.
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| 22. |
- Tettamanti, T., et al.
(författare)
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Robust real-time control for urban road traffic networks
- 2014
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Ingår i: IEEE Transactions on Intelligent Transportation Systems. - 1524-9050 .- 1558-0016. ; 15:1, s. 385-398
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the presented research is to elaborate a traffic-responsive optimal signal split algorithm taking uncertainty into account. The traffic control objective is to minimize the weighted link queue lengths within an urban network area. The control problem is formulated in a centralized rolling-horizon fashion in which unknown but bounded demand and queue uncertainty influences the prediction. An efficient constrained minimax optimization is suggested to obtain the green time combination, which minimizes the objective function when worst case uncertainty appears. As an illustrative example, a simulation study is carried out to demonstrate the effectiveness and computational feasibility of the robust predictive approach. By using real-world traffic data and microscopic traffic simulator, the proposed robust signal split algorithm is analyzed and compared with well-tuned fixed-time signal timing and to nominal predictive solutions under different traffic conditions.
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| 23. |
- Tettamanti, T., et al.
(författare)
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Uncertainty modeling and robust control in urban traffic
- 2011
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 1474-6670. - 9783902661937 ; 18:PART 1, s. 14910-14915
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Konferensbidrag (refereegranskat)abstract
- The paper investigates the problem of uncertainty modeling and constrained robust control of urban traffic. Linear polytopic approach is used by state-space representations to describe the uncertain network system. In order to handle model mismatches, robust and infinite horizon model predictive control (MPC) method is proposed. The control strategy is an efficient method to reduce travel time and improve homogeneous traffic flow under changing model conditions. Centralized numerical solution has been carried out as a solution of Linear Matrix Inequalities (LMI) by using semidefinite programming (SDP). Closed-loop control results were tested in simulation environment taking alternative model uncertainty levels into account.
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