SwePub - search: WFRF:(Köroglu Hakan 1971)

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1.	Dabiri, Azita, 1984, et al. (author) Distributed control of traffic flow in motorways 2014 In: 3rd National Transportation Conference, October 2014, Norrköping. Conference paper (peer-reviewed)
2.	Dabiri, Azita, 1984, et al. (author) Distributed LPV state-feedback control under control input saturation 2017 In: IEEE Transactions on Automatic Control. - 0018-9286 .- 1558-2523. ; 62:5, s. 2450-2456 Journal article (peer-reviewed)abstract Developed in this note is a scheduled state-feedback controller synthesis method for discrete-time Linear Parameter Varying (LPV) systems subjected to control input saturation constraints. The static state-feedback gain is scheduled with an exact replica of the parameter matrix. The saturation effect is modeled by introducing time-varying parameters as functions of the control inputs, which are also used to schedule the controller. The synthesis method is then specialized to distributed state-feedback by imposing a particular structure on the feedback gain matrix. An explicit formula is also derived for the computation of the distributed control input from a nonlinear equation. The viability of the proposed method is tested in a simulation environment, for a ramp meter traffic flow control problem.
3.	Dabiri, Azita, 1984, et al. (author) Distributed LPV State-Feedback Control with Application to Motorway Ramp Metering 2015 In: In proceedings of European Control Conference, ECC’15, July 15-17, Linz, Austria. - 9783952426937 ; , s. 1480-1485 Conference paper (peer-reviewed)abstract In this paper, we develop a distributed state-feedbackcontroller synthesis algorithm for a discrete-time LPVsystem that is composed of the interconnection of severalsubsystems each scheduled by its own parameters. A set ofLMI conditions are derived for robust L2-gain performanceof such a system in the framework of multiplier-based LPVsynthesis. The results have been oriented to be applied intraffic flow control in motorways by ramp metering. First,with the use of a proper transformation, the nonlineartraffic flow model has been represented as theinterconnection of LPV subsystems. Then the developedsynthesis results have been used to design a gain-scheduleddistributed state-feedback controller that keeps thedensity of all segments around a desired value by the useof ramp metering.
4.	Gupta, Ankit, 1988, et al. (author) Computation of low-complexity control-invariant sets for systems with uncertain parameter dependence 2019 In: Automatica. - : Elsevier BV. - 0005-1098. ; 101, s. 330-337 Journal article (peer-reviewed)abstract This paper considers the problem of computing a low-complexity robust control-invariant (LC-RCI) set for uncertain systems, along with a static linear state-feedback law. The LC-RCI set, assumed to be symmetric around the origin and described by the same number of affine inequalities as twice the dimension of the state vector, is the result of an iterative procedure, where semi-definite programs (SDPs) are solved at each step. The SDPs are formulated to increase the LC-RCI volume at each step, subject to tractable reformulations of the system constraints as well as the invariance condition (in the form of standard or dilated LMIs), and a new approach to determinant maximization. The two proposed algorithms are applicable to systems with rational parameter dependence, which cannot be handled with the existing similar approaches without introducing additional conservatism.
5.	Gupta, Ankit, 1988, et al. (author) Computation of Robust Control Invariant Sets with Predefined Complexity for Uncertain Systems 2021 In: International Journal of Robust and Nonlinear Control. - : Wiley. - 1099-1239 .- 1049-8923. ; 31:5, s. 1674-1688 Journal article (peer-reviewed)abstract This paper presents an algorithm that computes polytopic robust control-invariant (RCI) sets for rationally parameter-dependent systems with additive disturbances. By means of novel LMI feasibility conditions for invariance along with a newly developed method for volume maximization, an iterative algorithm is proposed for the computation of RCI sets with maximized volumes. The obtained RCI sets are symmetric around the origin by construction and have a user-defined level of complexity. Unlike many similar approaches, fixed state feedback structure is not imposed. In fact, a specific control input is obtained from the LMI problem for each extreme point of the RCI set. The outcomes of the proposed algorithm can be used to construct a piecewise-affine controller based on offline computations.
6.	Gupta, Ankit, 1988, et al. (author) Restricted-Complexity Characterization of Control-Invariant Domains with Application to Lateral Vehicle Dynamics Control 2017 In: IEEE Conference on Decision and Control. - 9781509028733 ; 2018-January, s. 4946-4951 Conference paper (peer-reviewed)abstract This paper proposes two algorithms to find a restricted-complexity robust control invariant (RCI) set along with a state-feedback gain. These algorithms are applicable to a linear system with additive disturbances subject to found polytopic state and input constraints. The RCI set is a polytope with restricted complexity, symmetric around the origin. Using a state transformation, novel LMI conditions are derived for the system constraints and invariance condition. Moreover, a new approach is proposed to iteratively increase the volume of the computed RCI set. The effectiveness of the proposed algorithm is illustrated by using lateral vehicle dynamics control example.
7.	Hosseini, Seyed Mehrdad, 1977, et al. (author) Estimation of parameters and delay in driver models using L1-regularization 2016 In: Proceedings of 2016 European Control Conference, ECC2016; Aalborg, Denmark; 29 June - 1 July 2016. - 9781509025909 ; , s. 945-950 Conference paper (peer-reviewed)abstract A new method is proposed for driver reaction time(delay) and parameter estimation using a generic lateral model that is expressed in terms of the steering angle, yaw rate and lateral lane offset. The idea behind the presented method is to reformulate the original driver model with an overparametrized one and then use the L1-regularization method to enforce sparsity and thereby estimate the delay together with the parameters of the original model. A sequential algorithm is then presented to obtain better estimates of the parameters with a model in which the delay is fixed.
8.	Köroglu, Hakan, 1971, et al. (author) Controller Synthesis for a Homogenous Platoon under Leader and Predecessor Following Scheme 2014 In: American Control Conference. - 0743-1619. - 9781479932726 ; , s. 1463-1468 Conference paper (peer-reviewed)abstract Synthesis of dynamic output-feedback controllers is considered in a homogenous platoon operating under the leader and predecessor following scheme. The problem is formulated as a multi-objective H∞-type synthesis in which the goal is to keep the worst-case spacing error variations induced by the maneuvers of the leader as small as possible, while also avoiding excessively large control inputs. Concerns about possible communication problems are also reflected in the problem formulation. Sufficient solvability conditions are then derived in the form of linear matrix inequalities, which also depend on a scalar parameter over which a line search has to be performed. It is also described how the transient behavior of the platoon can be shaped by a simple additional condition. The procedure is illustrated by some sample designs and simulations in the longitudinal control of vehicle platoons.
9.	Köroglu, Hakan, 1971 (author) H Infinity Synthesis with Unstable Weighting Filters: An LMI Solution 2013 In: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. - 9781467357142 ; , s. 2429-2434 Conference paper (peer-reviewed)abstract Synthesis of a controller is considered for achievinga desired level of guaranteed worst-case energy gain performance in the case of unstable (input and output) weighting filters. The solution of this problem is shown to require a proper replication of the unstable filter dynamics accompanied by a controller of free structure. By merging the replicated filter dynamics with the plant, the problem is reformulated as the design of the free part of the controller in a way to stabilize an extended plant and ensure the considered performance objective. A solution is then provided based on LMI conditions accompanied by affine equation constraints. A procedure is also outlined for the synthesis of a controller whose order is equal to the order of the plant plus the orders of the filters.
10.	Köroglu, Hakan, 1971 (author) Improved Conditions for Observer-Based LPV Control with Guaranteed L2-Gain Performance 2014 In: American Control Conference. - 0743-1619. - 9781479932726 ; , s. 3760-3765 Conference paper (peer-reviewed)abstract Synthesis of observer-based LPV controllers is considered with a guaranteed upper bound on the worst-case energy gain from the disturbance input to the performance output. A potentially conservative solution was derived for this problem before based on LMI optimization accompanied with a line search over a scalar variable. A new solution is provided in this paper based on a similar optimization problem, which has a comparable level of off-line computational complexity. It is shown that the new method cannot be any more conservative than the existing one. It is also verified by an example that the new solution can actually provide less conservative results. Another desirable feature of the new solution is that it is bettersuited for multi-objective synthesis.
11.	Köroglu, Hakan, 1971, et al. (author) Joint Synthesis of Dynamic Feed-Forward and Static State Feedback for Platoon Control 2014 In: Proceedings of the IEEE Conference on Decision and Control. - 0743-1546 .- 2576-2370. ; , s. 4503-4508 Conference paper (peer-reviewed)abstract Joint synthesis of static state-feedback and dynamic feed-forward is considered for a homogenous platoon operating under the leader and predecessor following scheme. The problem is formulated with two H-infinity type performance objectives. The first objective requires the first vehicle to respond in a desirable way to the maneuvers of the leader and it is to be realized by a joint synthesis of the feed-forward filter together with a state feedback gain. Novel LMI conditions are derived for this objective by fixing the order and the poles of the filter. The second objective aims at preventing the amplification of the errors backward along the platoon, while also maintaining robustness against communication problems with the leader. New sufficient LMI conditions are provided for this objective, based on which leader and predecessor feedback gain matrices can be constructed.
12.	Köroglu, Hakan, 1971, et al. (author) New LMI Conditions for Static Output Feedback Synthesis with Multiple Performance Objectives 2014 In: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. ; , s. 866-871 Conference paper (peer-reviewed)abstract The static output feedback synthesis problem is considered with H-infinity and generalized H-two performance objectives. New sufficient LMI conditions are derived for guaranteeing the required performance objectives. These conditions also depend on scalar parameters that need to be fixed beforehand. The output feedback gain matrix is computed from the involved matrix variables without the use of system matrices. Hence the conditions can directly be used to solve the multi-objective synthesis problem also for parameter-dependent systems with constant or parameter-dependent gain matrices. The method is illustrated in the adaptive cruise control problem.
13.	Köroglu, Hakan, 1971 (author) Observer-based linear parameter-varying control with guaranteed L2-gain and H2-type performance objectives 2014 In: International Journal of Robust and Nonlinear Control. - : Wiley. - 1099-1239 .- 1049-8923. ; 24:14, s. 2000-2017 Journal article (peer-reviewed)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.
14.	Köroglu, Hakan, 1971, et al. (author) Platoon Control based on Predecessor and Delayed Leader Information 2016 In: Reglermöte 2016. Conference paper (other academic/artistic)abstract The platoon control problem is considered with a leader and predecessor following scheme. A novel velocity-dependent spacing policy is integrated into this scheme in order to improve robustness against the communication delay with the leader. The velocity dependence is adjusted in this scheme with a scalar parameter that appears as the constant time headway in the standard predecessor following scheme. The design problem is considered with a first-order vehicle model and a simple PD-type controller. It is shown that formation stability can always be ensured with sufficient emphasis on the predecessor information. On the other hand, string stability can be achieved only when the headway parameter is chosen larger than the communication delay. It is also outlined how the feedback gains and the emphasis on the leader can be adjusted for desirable performance.
15.	Köroglu, Hakan, 1971, et al. (author) Platoon Control based on Predecessor and Delayed Leader Information via Minimized Headway Times 2020 In: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. ; 2020-December, s. 2857-2862 Conference paper (peer-reviewed)abstract The platoon control problem is considered under a recently proposed leader and predecessor following scheme with a third-order vehicle dynamics. The scheme is investigated with a simple PD-type controller in the face of delayed leader information. It is shown that string stability can be achieved only when the headway parameter is chosen larger than the communication delay. The use of larger headway parameters is also shown to be necessary to avoid the amplification of the acceleration signals backward along the platoon. Guidelines are given for the choice of controller gains and the headway parameter in a way to achieve desirable platoon behavior.
16.	Köroglu, Hakan, 1971, et al. (author) Platoon Control under a Novel Leader and Predecessor Following Scheme with the Use of an Advanced Aerodynamic Model 2018 In: Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME. - : ASME International. - 0022-0434 .- 1528-9028. ; 140:4 Journal article (peer-reviewed)abstract The longitudinal platoon control problem is considered under a leader and predecessor following scheme with a novel velocity-dependent spacing policy. With this spacing policy, the steady-state inter-vehicle distances increase with increasing cruise velocity and more so for vehicles that are closer to the leader.} Since significant changes might be encountered in inter-vehicle distances during the travel due to the variations in the velocity of the leader, the problem is studied together with a more accurate modeling of aerodynamic effects within a platoon formation. Based on a standard feedback linearization approach, a dynamic output feedback synthesis problem is formulated with two H_infinity performance objectives. One of the performance objectives is linked to the string stability of the platoon formation, while the other can be shaped in a way to maintain small spacing errors without aggressive vehicle maneuvers. A synthesis procedure is then outlined based on linear matrix inequality optimization. The new control scheme is investigated for a three-vehicle platoon by using an advanced aerodynamic model developed based on extensive fluid dynamics simulations. It is observed in this investigation that a desirable platoon operation can be achieved even with a simple aerodynamic model, provided that the controller is designed in a way to ensure good disturbance attenuation. Nevertheless an accurate modeling of aerodynamic disturbances might be needed especially for the first vehicle after the leader when the cruising velocity varies over a wide range.
17.	Köroglu, Hakan, 1971, et al. (author) Robust static output feedback synthesis for platoons under leader and predecessor feedback 2017 In: International Journal of Robust and Nonlinear Control. - : Wiley. - 1099-1239 .- 1049-8923. ; 27:10, s. 1726-1756 Journal article (peer-reviewed)abstract A multi-objective static output feedback synthesis problem is considered for the control of vehicle platoonsunder leader and predecessor feedback. Sufficient linear matrix inequality conditions are derived for thesolvability of the problem in a way to facilitate static feed-forward as well. A novel velocity-dependent spacingpolicy is integrated into the control scheme together with a platoon model in which the emphasis on thepredecessor information can be adjusted by a normalized scalar weight. It is shown that the string stability ofthe spacing errors and the acceleration signals can always be guaranteed by choosing this weight sufficientlysmall. Moreover, provided that the time headway is chosen sufficiently large, the synthesis can be performedin a way to avoid the amplification of acceleration energies if compared with the leader. As a particularlyconvenient feature, the target spacing between the vehicles becomes smaller when moving backward alongthe platoon. The total increase in the platoon length caused by the introduction of the velocity-dependentscheme is shown to be bounded and decreasing with decreasing predecessor weight. It is also establishedthat the predecessor weight can be adjusted smoothly over time without endangering the formation stability.In addition to the optimization of the parameters of common fixed-structure controllers for general vehicle models, the proposed synthesis procedure provides various tools for improving robustness against measurement noise, communication delay, and model uncertainty.
18.	Köroglu, Hakan, 1971, et al. (author) Robust Static Output Feedback Synthesis under an Integral Quadratic Constraint on the States 2015 In: Proceedings of 2015 European Control Conference. - 9783952426944 ; , s. 3208-3213 Conference paper (peer-reviewed)abstract The static output feedback synthesis problem is considered under an integral quadratic constraint on the states. The problem is formulated as a multi-objective synthesis in which an H-infinity performance objective is to be guaranteed in addition to the integral quadratic constraint. Sufficient LMI conditions are then derived for the solvability of the problem. Extension to parameter-dependent systems is also discussed briefly. The developed method is then applied to the control of a heterogenous platoon formed by three vehicles.
19.	Köroglu, Hakan, 1971, et al. (author) State Feedback Synthesis for Homogenous Platoons under the Leader and Predecessor Following Scheme 2014 In: Proceedings of European Control Conference, June 24-27, 2014, Strasbourg, France. - 9783952426913 ; , s. 2655-2660 Conference paper (peer-reviewed)abstract Synthesis of state-feedback controllers is considered for a homogenous platoon operating under the leader and predecessor following scheme. The problem is formulated as a multi-objective H-infinity type synthesis. The performance specifications are shaped by the string stability objective and prevention of extensive control effort, as well as by the concerns about the communication problems with the leader. Sufficient LMI conditions are then provided for the synthesis of common statefeedback gains. Some aspects of the developed approach are illustrated in the longitudinal control of a vehicle platoon.
20.	Sadeghi Kati, Maliheh, 1979, et al. (author) H ∞ Static Output Feedback Synthesis under an Integral Quadratic Constraint with Application to High Capacity Transport Vehicles 2016 In: In proceedings of European Control Conference, ECC 16. ; , s. 1999-2004 Conference paper (peer-reviewed)abstract This paper proposes a new linear matrix inequality (LMI) approach for H ∞ static output feedback synthesis under an integral quadratic constraint (IQC) on the states. The proposed approach is applicable to a wider class of systems if compared to the relevant previous work. The new sufficient LMI condition for the IQC constraint might also preferable to work with when considering systems that have affine parameter dependence in the descriptor form. As a particularly relevant application, the proposed approach is then considered for the control of a high capacity transport vehicle to enhance itslateral performance. The verification results confirm significant reductions in rearward amplification of yaw rates and high speed transient offtracking for the nominal system.
21.	Sadeghi Kati, Maliheh, 1979, et al. (author) ROBUST CONTROL OF AN A-DOUBLE WITH ACTIVE DOLLY BASED ON STATIC OUTPUT FEEDBACK AND DYNAMIC FEED-FORWARD 2016 In: 14th International Heavy Vehicle Transport Technology Symposium. Conference paper (peer-reviewed)abstract A steering-based control is proposed for improving the lateral performance of anA-double combination with an active dolly. The controller is based on static outputfeedback combined with dynamic feed-forward and is designed to ensure an H ∞performance objective in the face of parametric uncertainty. The synthesis is per-formed via linear matrix inequality (LMI) optimizations. Two feed-forward designmethods are proposed and one of them is highlighted as the more rigorous approachfor dealing with parametric uncertainty. The verification results confirm a significantreduction in rearward amplification of yaw rates and high speed transient off-trackingeven when the dynamic feed-forward from the tractor steering angle accompaniesthe static feedback only from the articulation angles.
22.	Sadeghi Kati, Maliheh, 1979, et al. (author) Robust Lateral Control of an A-double combination via H∞ and Generalized H2 Static Output Feedback 2016 In: IFAC-PapersOnLine. - : Elsevier BV. - 2405-8963. ; 49:11, s. 305-311 Conference paper (peer-reviewed)abstract A robust static output feedback controller is developed for improving the high speed lateral performance of an A-double combination by active steering of the dolly unit. The controller is designed to be robust against the uncertainty in the cornering stiffness parameters of the tires in the semitrailers. Both H∞ and generalized H2 synthesis approaches are discussed together with their solutions in the form of linear matrix inequality (LMI) optimizations. The control syntheses are then applied to both a fixed system and an uncertain parameter-dependent system. The verification results confirm a significant reduction in rearward amplification of yaw rates and high speed transient off-tracking. To validate the simulation results, an advanced high-fidelity vehicle model is used.
23.	Sadeghi Kati, Maliheh, 1979, et al. (author) Robust Lateral Control of long-combination vehicles under Moments of Inertia and Tire Cornering Stiffness Uncertainties 2019 In: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 52:12, s. 1847-1873 Journal article (peer-reviewed)abstract A robust steering-based controller synthesis is presented for an A-double combination vehicle with a steerable dolly. The controller ensures robust stability and performance in the face of uncertainties in the cornering stiffness of the tyres and the moments of inertia of the semitrailers, which are treated as time-varying and time-invariant parameters respectively. A descriptor-type representation of the system is employed since a standard state-space model depends rationally on the moments of inertia. The controller synthesis is formulated as an Hinfinity-type static output feedback, which uses information from only one articulation angle. The driver steering input is also used by including a static feed-forward. The proposed synthesis method is based on linear matrix inequality (LMI) optimisation. The controller is verified based on the simulation results obtained from both (approximate) linear and (high-fidelity) nonlinear vehicle models. The results indicate significant improvement in the high-speed lateral performance of the A-double in the presence of parametric uncertainties.
24.	Veenman, Joost, et al. (author) Robust stability and performance analysis based on integral quadratic constraints 2016 In: European Journal of Control. - : Elsevier BV. - 0947-3580. ; 31, s. 1-32 Journal article (peer-reviewed)abstract The integral quadratic constraints (IQC) approach facilitates a systematic and efficient analysis of robust stability and performance for uncertain dynamical systems based on linear matrix inequality (LMI) optimization. With the intention to make the IQC analysis tools more accessible to control scientists and engineers, we present in this paper a tutorial overview in three main parts: i) the general setup and the basic IQC theorem, ii) an extensive survey on the formulation and parametrization of multipliers based on LMI constraints, and iii) a detailed illustration of how the tools can be applied.

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