| 1. |
- Andersson, Alina, et al.
(författare)
-
Analytic Parameterization of Stabilizing Controllers for the Surge Subsystem of the Moore-Greitzer Compressor Model
- 2013
-
Ingår i: Proc. 2013 American Control Conference (ACC2013). - 0743-1619. - 9781479901777 ; , s. 5257-5262
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Konferensbidrag (refereegranskat)abstract
- This paper is based on a new procedure for dynamic output feedback design for systems with nonlinearities satisfying quadratic constraints. The new procedure is motivated by the challenges of output feedback control design for the 3-state Moore-Greitzer compressor model. First, we use conditions for stability of a transformed system and the associated matching conditions to find the data of the stabilizing controllers for the surge subsystem. Second, using the set of stabilizing controllers satisfying the given constraints for the closed-loop system with the dynamic output feedback controller we made optimization over the parameter set. We present the data of the stabilizing controllers and the new constraints for the corresponding parameters. The contributions in this paper are simplified conditions for the synthesis and optimization over the control parameter set.
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| 2. |
- Berntorp, Karl, et al.
(författare)
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Models and Methodology for Optimal Vehicle Maneuvers Applied to a Hairpin Turn
- 2013
-
Ingår i: 2013 American Control Conference. - 0743-1619. - 9781479901777 ; , s. 2139-2146
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Konferensbidrag (refereegranskat)abstract
- There is currently a strongly growing interest in obtaining optimal control solutions for vehicle maneuvers, both in order to understand optimal vehicle behavior and to devise improved safety systems, either by direct deployment of the solutions or by including mimicked driving techniques of professional drivers. However, it is nontrivial to find the right mix of models, formulations, and optimization tools to get useful results for the above purposes. Here, a platform is developed based on a state-of-the-art optimization tool together with adoption of existing vehicle models, where especially the tire models are in focus. A minimum-time formulation is chosen to the purpose of gaining insight in at-the-limit maneuvers, with the overall aim of possibly finding improved principles for future active safety systems. We present optimal maneuvers for different tire models with a common vehicle motion model, and the results are analyzed and discussed. Our main result is that a few-state single-track model combined with different tire models is able to replicate the behavior of experienced drivers. Further, we show that the different tire models give quantitatively different behavior in the optimal control of the vehicle in the maneuver.
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| 3. |
- Luspay, T., et al.
(författare)
-
Mean-square optimal control of Linear Parameter Varying systems
- 2013
-
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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| 4. |
- Stotsky, Alexander, 1960, et al.
(författare)
-
Control of wind turbines: A tutorial on proactive perspectives
- 2013
-
Ingår i: American Control Conference. - : IEEE. - 0743-1619. - 9781479901777 ; , s. 3429-3436
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Konferensbidrag (refereegranskat)abstract
- Recent achievements in the proactive turbine control1, based on the upwind speed measurements are described in a unified tutorial fashion (as an extension of the tutorial [1]), that in turn represents a systematic view of the control activity carried out within the Swedish Wind Power Technology Center (SWPTC). A new turbine control problem statement with constraints on blade loads is reviewed. This problem statement allows the design of a new class of simultaneous speed and pitch control strategies based on the preview measurements and look-ahead calculations. A generation of a piecewise constant desired pitch angle profile which is calculated using the turbine load prediction is reviewed in this paper as one of the most promising approaches. This in turn allows the reduction of the pitch actuation and the design of the collective pitch control strategy with the maximum possible actuation rate.
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| 5. |
- Ali, Mohammad, 1982, et al.
(författare)
-
Model-Based Threat Assessment for Lane Guidance Systems
- 2011
-
Ingår i: American Control Conference. - 0743-1619. - 9781457700804 ; , s. 4586-4591
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Konferensbidrag (refereegranskat)abstract
- This paper considers a threat assessment problem in a lane guidance application for semi-autonomous vehicles. In particular, in order to issue an autonomous assisting intervention, we assess the vehicle’s ability to safely travel along a path subject to limitations arising from the vehicle’s dynamics and the driver’s ability.We first introduce a set of constraints describing “safedriving”. For the specific lane guidance application considered in this paper, the constraints are set by the lane boundaries and the vehicle’s stability limits. We then formulate the threat assessment problem as a constraints satisfaction problem over a finite time horizon, solved by resorting to reachabililty analysisand invariant set theory.Validation with experimental data demonstrates the capability of the proposed threat assessment method of predicting vehicle instability or crossing of the lane boundaries.
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| 6. |
- Berntorp, Karl, et al.
(författare)
-
Path Tracking with Obstacle Avoidance for Pseudo-Omnidirectional Mobile Robots Using Convex Optimization
- 2014
-
Ingår i: [Host publication title missing]. - 0743-1619. ; , s. 517-524
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Konferensbidrag (refereegranskat)abstract
- We consider the problem of trajectory generation for time-optimal path tracking for the class of pseudo-omnidirectional mobile robots. An Euler-Lagrange model of the robot dynamics is derived, and by writing it on special form a convex reformulation of the path-tracking problem can be utilized. This enables the use and regeneration of time-optimal trajectories during runtime. The proposed approach also incorporates avoidance of moving obstacles, which are unknown a priori. Using sensor data, objects along the desired path are detected. Subsequently, a new path is planned and the corresponding time-optimal trajectory is found. The robustness of the method and its sensitivity to model errors are analyzed and discussed with extensive simulation results. Moreover, we verify the approach by successful execution on a physical setup.
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| 7. |
- Chasparis, Georgios, et al.
(författare)
-
Distributed Management of CPU Resources for Time-Sensitive Applications
- 2013
-
Ingår i: [Host publication title missing]. - 0743-1619. ; , s. 5305-5312
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Konferensbidrag (refereegranskat)abstract
- The number of applications sharing the same embedded device is increasing dramatically. Very efficient mechanisms (resource managers) for assigning the CPU time to all demanding applications are needed. Unfortunately, existing optimization-based resource managers consume too much resource themselves. In this paper, we address the problem of distributed convergence to fair allocation of CPU resources for time-sensitive applications. We propose a novel resource management framework where both applications and the resource manager act independently trying to maximize their own performance measure according to a utility-based adjustment process. Contrary to prior work on centralized optimization schemes, the proposed framework exhibits adaptivity and robustness to changes both in the number and nature of applications, while it assumes minimum information available to both applications and the resource manager. It is shown analytically that fair resource allocation can be achieved through the proposed adjustment process when the CPU is overloaded. Experiments using the TrueTime Matlab toolbox show the validity of the proposed approach.
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| 8. |
- Durr, H. -B, et al.
(författare)
-
Obstacle avoidance for an extremum seeking system using a navigation function
- 2013
-
Ingår i: Proceedings of the American Control Conference 2013. - : AACC American Automatic Control Council. - 9781479901777 ; , s. 4062-4067
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Konferensbidrag (refereegranskat)abstract
- The problem of autonomously steering a vehicle to a destination point, while avoiding obstacles, is considered. The vehicle is modeled as a single-integrator in the plane and it is assumed that the obstacles are unknown a priori. The control law is an extremum seeking algorithm, which steers the vehicle to the minimum of a navigation function. In this framework, obstacle avoidance and practical uniform convergence to a destination point for almost all initial conditions is proven. The theoretic results are illustrated using numerical examples.
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| 9. |
- Farokhi, Farhad, 1987-, et al.
(författare)
-
Complexity Reduction for Parameter-Dependent Linear Systems
- 2013
-
Ingår i: 2013 American Control Conference (ACC). - : American Automatic Control Council. - 9781479901777 ; , s. 2624-2630
-
Konferensbidrag (refereegranskat)abstract
- We present a complexity reduction algorithm for a family of parameter-dependent linear systems when the system parameters belong to a compact semi-algebraic set. This algorithm potentially describes the underlying dynamical system with fewer parameters or state variables. To do so, it minimizes the distance (i.e., $H_\infty$-norm of the difference) between the original system and its reduced version. We present a sub-optimal solution to this problem using sum-of-squares optimization methods. We present the results for both continuous-time and discrete-time systems. Lastly, we illustrate the applicability of our proposed algorithm on numerical examples.
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| 10. |
- Giselsson, Pontus
(författare)
-
A generalized distributed accelerated gradient method for distributed model predictive control with iteration complexity bounds
- 2013
-
Ingår i: [Host publication title missing]. - 0743-1619. ; , s. 327-333
-
Konferensbidrag (refereegranskat)abstract
- Most distributed optimization methods used for distributed model predictive control (DMPC) are gradient based. Gradient based optimization algorithms are known to have iterations of low complexity. However, the number of iterations needed to achieve satisfactory accuracy might be significant. This is not a desirable characteristic for distributed optimization in distributed model predictive control. Rather, the number of iterations should be kept low to reduce communication requirements, while the complexity within an iteration can be significant. By incorporating Hessian information in a distributed accelerated gradient method in a well-defined manner, we are able to significantly reduce the number of iterations needed to achieve satisfactory accuracy in the solutions, compared to distributed methods that are strictly gradient-based. Further, we provide convergence rate results and iteration complexity bounds for the developed algorithm.
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| 11. |
- Giselsson, Pontus
(författare)
-
Optimal preconditioning and iteration complexity bounds for gradient-based optimization in model predictive control
- 2013
-
Ingår i: [Host publication title missing]. - 0743-1619. ; , s. 358-364
-
Konferensbidrag (refereegranskat)abstract
- In this paper, optimization problems arising in model predictive control (MPC) and in distributed MPC aresolved by applying a fast gradient method to the dual of the MPC optimization problem. Although the development of fast gradient methods has improved the convergence rate of gradient-based methods considerably, they are still sensitive to ill-conditioning of the problem data. Since similar optimization problems are solved several times in the MPC controller, the optimization data can be preconditioned offline to improve the convergence rate of the fast gradient method online. A natural approach to precondition the dual problem is to minimize the condition number of the Hessian matrix. However, in MPC the Hessian matrix usually becomes positive semi-definite only, i.e., the condition number is infinite and cannot be minimized. In this paper, we show how to optimally precondition the optimization data by solving a semidefinite program, where optimally refers to the preconditioning that minimizes an explicit iteration complexity bound. Although the iteration bounds can be crude, numerical examples show that the preconditioning can significantly reduce the number of iterations needed to achieve a prespecified accuracy of the solution.
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| 12. |
- Giselsson, Pontus
(författare)
-
Output feedback distributed model predictive control with inherent robustness properties
- 2013
-
Ingår i: [Host publication title missing]. - 0743-1619. ; , s. 1691-1696
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Konferensbidrag (refereegranskat)abstract
- We consider robust output feedback distributed model predictive control (DMPC). The proposed controller is based on the results in [8] in which nominal stability and feasibility was proven for a DMPC-formulation without terminal constraint set or terminal cost in the optimization. We extend these results to show robust stability under state feedback as well as output feedback when dynamics and measurements are affected by bounded noise. The provided numerical example suggests that the region of attraction without terminal constraint set may be significantly larger than if a terminal constraint set is used.
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| 13. |
- Grip, H. F., et al.
(författare)
-
Output synchronization for heterogeneous networks of non-introspective, non-right-invertible agents
- 2013
-
Ingår i: Proceedings of the American Control Conference 2013. - : American Automatic Control Council. - 9781479901777 ; , s. 5791-5796
-
Konferensbidrag (refereegranskat)abstract
- We consider the output synchronization problem for a heterogeneous network of linear agents. The agents are non-introspective, meaning that they do not have access to their own state or output; the only information available to each agent comes from the network, in the form of a linear combination of its output relative to that of neighboring agents. The basis for our study is a design previously presented by the authors, which was based on an additional assumption requiring the agents to be right-invertible. Here we dispense with the assumption of right-invertibility and instead introduce a new assumption based on solvability of a particular set of regulator equations.
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| 14. |
- Hedegärd, Marcus, 1979, et al.
(författare)
-
Convex identification of models for asymmetric hysteresis
- 2014
-
Ingår i: American Control Conference. - 0743-1619. - 9781479932726 ; , s. 4753-4758
-
Konferensbidrag (refereegranskat)abstract
- The generalized Prandtl-Ishlinskii model (GPI) of hysteresis has a wide applicability, partly because of its capability of modelling highly asymmetric hysteresis. A disadvantage of the GPI models compared to, for example the Modified Prandtl-Ishlinskii models, has been that they have had to be identified using parametric non convex methods. Recently though, a method for non-parametric convex identification for an extended and more general GPI model was described, giving all model functions. Here, the method, which was based on input discrete equations, is briefly presented in terms of the corresponding input continuous equations. This extended model corresponds to a Preisach model and an explicit expression for this relation is derived. The method is directly applicable to data consisting of first order reversal curves, but in an application to an electrical substation equipment, it is shown that other kinds of data can also be used. The method gives significantly closer fit to this data than previous studies, and it demonstrates that non-equal left and right envelope functions are optimal.
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| 15. |
- Henningsson, Maria, et al.
(författare)
-
Dynamic Mapping of Diesel Engine through System Identification
- 2010
-
Ingår i: Proceedings of the 2010 American Control Conference. - 2378-5861 .- 0743-1619. - 9781424474264 - 9781424474271 ; , s. 3015-3020
-
Konferensbidrag (refereegranskat)abstract
- From a control design point of view, modern diesel engines are dynamic, nonlinear, MIMO systems. This paper presents a method to find low-complexity black-box dynamic models suitable for model predictive control (MPC) of NOx and soot emissions based on on-line emissions measurements. A four-input-five-output representation of the engine is considered, with fuel injection timing, fuel injection duration, exhaust gas recirculation (EGR) and variable geometry turbo (VGT) valve positions as inputs, and indicated mean effective pressure, combustion phasing, peak pressure derivative, NOx emissions, and soot emissions as outputs. Experimental data were collected on a six-cylinder heavy-duty engine at 30 operating points. The identification procedure starts by identifying local linear models at each operating point. To reduce the number of dynamic models necessary to describe the engine dynamics, Wiener models are introduced and a clustering algorithm is proposed. A resulting set of two to five dynamic models is shown to be able to predict all outputs at all operating points with good accuracy.
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| 16. |
- Ishizaki, T., et al.
(författare)
-
Structured model reduction of interconnected linear systems based on singular perturbation
- 2013
-
Ingår i: Proceedings of the American Control Conference 2013. - : American Automatic Control Council. - 9781479901777 ; , s. 5524-5529
-
Konferensbidrag (refereegranskat)abstract
- This paper proposes a singular perturbation approximation that preserves system passivity and an interconnection topology among subsystems. In the first half of this paper, we develop a singular perturbation approximation valid for stable linear systems. Using the relation between the singular perturbation and the reciprocal transformation, we derive a tractable expression of the error system in the Laplace domain, which provides a novel insight to regulate the approximating quality of reduced models. Then in the second half, we develop a structured singular perturbation approximation that focuses on a class of interconnected systems. This structured approximation provides a reduced model that not only possesses fine approximating quality, but also preserves the original interconnection topology and system passivity.
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| 17. |
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| 18. |
- Katselis, Dimitrios, et al.
(författare)
-
Efficient OOK/DS-CDMA Detection Threshold Selection
- 2013
-
Ingår i: 2013 American Control Conference (ACC). - : American Automatic Control Council. - 9781479901777 ; , s. 3523-3528
-
Konferensbidrag (refereegranskat)abstract
- A major constraint in deployments of wireless sensor networks (WSNs) is the energy consumption related to the battery lifetime of the network nodes. To this end, power efficient digital modulation techniques such as On-Off keying (OOK) are highly attractive. However, the OOK detection thresholds, namely the thresholds against which the received signals are compared to detect which bit is transmitted, must be carefully selected to minimize the bit error rate. This is challenging to accomplish in resource-limited nodes with constrained computational capabilities. In this paper, the system scenario considers simultaneously transmitting nodes in Rayleigh fading conditions. Various iterative algorithms to numerically select the detection thresholds are established. Convergence analysis accompanies these algorithms. Numerical simulations are provided to support the derived results and to compare the proposed algorithms. It is concluded that OOK modulation is beneficial in resource constrained WSNs provided that efficient optimization algorithms are employed for the threshold selection.
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| 19. |
- Kjaer, Martin Ansbjerg, et al.
(författare)
-
Analysis of Buffer Delay in Web-Server Control
- 2010
-
Ingår i: 2010 American Control Conference. - 0743-1619. ; , s. 1047-1052
-
Konferensbidrag (refereegranskat)abstract
- This paper addresses a problem related to control of web servers. Due to architectual issues, relevant measurements can only be taken over a limited part of the server system, which leaves the controller unaware of what happens in buffers proceeding the actual web-server (for instance, in the TCP/IP layers). In earlier presented work we modeled such a system and proved that the unmeasured buffering turned a measurement of an input disturbance into a state-dependent variable. In this paper we investigate how these new properties effect a traditional control design consisting of feedback in combination with a feed-forward mechanism. The stability analysis suggests that under certain circumstances, the system enters limit cycles due to the feedback mechanism introduced by the designed feed-forward controller. We verify the analysis by both simulations and experiments.
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| 20. |
- Kozma, A., et al.
(författare)
-
An improved distributed dual newton-CG method for convex quadratic programming problems
- 2014
-
Ingår i: American Control Conference. - 0743-1619. - 9781479932726 ; , s. 2324-2329
-
Konferensbidrag (refereegranskat)abstract
- This paper considers the problem of solving Programs (QP) arising in the context of distributed optimization and optimal control. A dual decomposition approach is used, where the QP subproblems are solved locally, while the constraints coupling the different subsystems in the time and space domains are enforced by performing a distributed non-smooth Newton iteration on the dual variables. The iterative linear algebra method Conjugate Gradient (CG) is used to compute the dual Newton step. In this context, it has been observed that the dual Hessian can be singular when a poor initial guess for the dual variables is used, hence leading to a failure of the linear algebra. This paper studies this effect and proposes a constraint relaxation strategy to address the problem. It is both formally and experimentally shown that the relaxation prevents the dual Hessian singularity. Moreover, numerical experiments suggest that the proposed relaxation improves significantly the convergence of the Distributed Dual Newton-CG.
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| 21. |
- Köroglu, Hakan, 1971, et al.
(författare)
-
Controller Synthesis for a Homogenous Platoon under Leader and Predecessor Following Scheme
- 2014
-
Ingår i: American Control Conference. - 0743-1619. - 9781479932726 ; , s. 1463-1468
-
Konferensbidrag (refereegranskat)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.
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| 22. |
- Köroglu, Hakan, 1971
(författare)
-
Improved Conditions for Observer-Based LPV Control with Guaranteed L2-Gain Performance
- 2014
-
Ingår i: American Control Conference. - 0743-1619. - 9781479932726 ; , s. 3760-3765
-
Konferensbidrag (refereegranskat)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.
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| 23. |
- Larsson, Christian, et al.
(författare)
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Generation of excitation signals with prescribed autocorrelation for input and output constrained systems
- 2013
-
Ingår i: 2013 American Control Conference (ACC). - : American Automatic Control Council. - 9781479901777 ; , s. 3918-3923
-
Konferensbidrag (refereegranskat)abstract
- This paper considers the problem of realizing an input signal with a desired autocorrelation sequence satisfying both input and output constraints for the system it is to be applied to. This is a important problem in system identification. Firstly, the properties of the identified model are highly dependent on the used excitation signal during the experiment and secondly, on real processes, due to actuator saturation and safety considerations, it is important to constrain the inputs and outputs of the process. The proposed method is formulated as a nonlinear model predictive control problem. In general this corresponds to solving a non-convex optimization problem. Here we show how this can be solved in one particular case. For this special case convergence is established for generation of pseudo-white noise. The performance of the algorithm is successfully verified by simulations for a few different autocorrelation sequences, with and without input and output constraints.
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| 24. |
- Larsson, Viktor, 1984, et al.
(författare)
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Benefit of Route Recognition in Energy Management of Plug-in Hybrid Electric Vehicles
- 2012
-
Ingår i: Proceedings of the American Control Conference. - : IEEE. - 0743-1619. - 9781457710940 ; , s. 1314-1320
-
Konferensbidrag (refereegranskat)abstract
- This paper investigates the benefit of an energymanagement system that autonomously can recognize when aplug-in hybrid electric vehicle is driven along known commutingroutes. The presented route recognition algorithm comparesthe GPS trajectory of the ongoing trip with stored commutingroutes using the well known cross-correlation operation. If aroute is recognized the energy management system switchesfrom a charge depleting charge sustaining discharge strategyto a strategy where the battery discharge rate is adapted to thelength of the recognized route, thereby decreasing the averagedischarge current and the resistive losses.The proposed system is evaluated using simulations onone month of logged commuter driving data. The resultsfor an energy management system based on the equivalentconsumption minimization strategy indicate an overall fuel costreduction of 1.5% compared to an system that only utilize acharge depleting charge sustaining strategy.
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| 25. |
- Lessard, Laurent, et al.
(författare)
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Optimal controller synthesis for the decentralized two-player problem with output feedback
- 2012
-
Ingår i: American Control Conference (ACC), 2012. - 0743-1619. - 9781457710957 ; , s. 6314-6321
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Konferensbidrag (refereegranskat)abstract
- In this paper, we present a controller synthesis algorithm for a decentralized control problem. We consider an architecture in which there are two interconnected linear subsystems. Both controllers seek to optimize a global quadratic cost, despite having access to different subsets of the available measurements. Many special cases of this problem have previously been solved, most notably the state-feedback case. The generalization to output-feedback is nontrivial, as the classical separation principle does not hold. Herein, we present the first explicit state-space realization for an optimal controller for the general two-player problem.
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| 26. |
- Lewander, Magnus, et al.
(författare)
-
Steady state fuel consumption optimization through feedback control of estimated cylinder individual efficiency
- 2012
-
Ingår i: Proceedings of the 2012 American Control Conference. - 0743-1619 .- 2378-5861. - 9781457710957 - 9781457710964 ; , s. 4210-4214
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Konferensbidrag (refereegranskat)abstract
- Engine efficiency is often controlled in an indirectway through combustion timing control. This requires a prioriknowledge of where to phase the combustion for differentoperating points and conditions. With cylinder individual efficiencyestimation, control strategies aiming directly at fuelconsumption optimization can be developed. It has previouslybeen shown that indicated efficiency can be estimated using thecylinder pressure trace. This paper presents a method to usethe estimated efficiency as a feedback variable in an extremumseeking control strategy for online steady state fuel consumptionoptimization. The experimental results show that the controllermanages to find the maximum brake torque region at the givenoperating point both with and without external excitation.
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| 27. |
- Luspay, T., et al.
(författare)
-
Freeway ramp metering: an LPV set theoretical analysis
- 2011
-
Ingår i: American Control Conference. - 0743-1619. - 9781457700804 ; , s. 733-738
-
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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| 28. |
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| 29. |
- Oomen, T., et al.
(författare)
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Iteratively learning the H∞-norm of multivariable systems applied to model-error-modeling of a vibration isolation system
- 2013
-
Ingår i: Proceedings of the American Control Conference 2013. - : American Automatic Control Council. - 9781479901777 ; , s. 6703-6708
-
Konferensbidrag (refereegranskat)abstract
- The aim of this paper is to develop a new data-driven approach for learning the H∞-norm of multivariable systems that can be used for model-error-modeling in robust feedback control. The proposed algorithm only requires iterative experiments on the system. Especially for the multivariable situation that is considered in this paper, these experiments have to be judiciously chosen. The proposed algorithm delivers an estimate of the H ∞-norm of an unknown multivariable system, without the need or explicit construction of a (parametric or non-parametric) model. The results are experimentally demonstrated on model-error-modeling of a multivariable industrial active vibration isolation system. Finally, connections to learning control algorithms are established.
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| 30. |
- 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
-
Ingår i: American Control Conference. - : IEEE. - 0743-1619. - 9781457710957 ; , s. 1543-1548
-
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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| 31. |
- Romero Segovia, Vanessa, et al.
(författare)
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Noise filtering in PI and PID Control
- 2013
-
Ingår i: American Control Conference, 2013. - 0743-1619. ; , s. 1763-1770
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Konferensbidrag (refereegranskat)abstract
- Control design is a rich problem which requires a compromise between performance and robustness. This paper explores how filtering of the measured signal influences the undesirable control actions generated by measurement noise, the load disturbance response, and the robustness to process uncertainty. The analysis is condensed to design rules.
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| 32. |
- Shi, Guodong, et al.
(författare)
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Convergence of Distributed Averaging and Maximizing Algorithms : Part II: State-dependent Graphs
- 2013
-
Ingår i: 2013 American Control Conference. - : American Automatic Control Council. - 9781479901777 ; , s. 6859-6864
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Konferensbidrag (refereegranskat)abstract
- In this paper, we formulate and investigate a generalized consensus algorithm which makes an attempt to unify distributed averaging and maximizing algorithms considered in the literature. Each node iteratively updates its state as a time-varying weighted average of its own state, the minimal state, and the maximal state of its neighbors. In Part I of the paper, time-dependent graphs are studied. This part of the paper focuses on state-dependent graphs. We use a μ-nearest-neighbor rule, where each node interacts with its μ nearest smaller neighbors and the μ nearest larger neighbors. It is shown that μ+1 is a critical threshold on the total number of nodes for the transit from finite-time to asymptotic convergence for averaging, in the absence of node self-confidence. The threshold is 2μ if each node chooses to connect only to neighbors with unique values. The results characterize some similarities and differences between distributed averaging and maximizing algorithms.
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| 33. |
- Shi, Guodong, et al.
(författare)
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Convergence of distributed averaging and maximizing algorithms : Part I: Time-dependent graphs
- 2013
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Ingår i: 2013 American Control Conference (ACC). - : American Automatic Control Council. - 9781479901777 ; , s. 6096-6101
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Konferensbidrag (refereegranskat)abstract
- In this paper, we formulate and investigate a generalized consensus algorithm which makes an attempt to unify distributed averaging and maximizing algorithms considered in the literature. Each node iteratively updates its state as a time-varying weighted average of its own state, the minimal state, and the maximal state of its neighbors. This part of the paper focuses on time-dependent communication graphs. We prove that finite-time consensus is almost impossible for averaging under this uniform model. Then various necessary and/or sufficient conditions are presented on the consensus convergence. The results characterize some similarities and differences between distributed averaging and maximizing algorithms.
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| 34. |
- Soltesz, Kristian, et al.
(författare)
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Transfer Function Parameter Identification by Modified Relay Feedback
- 2010
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Ingår i: 2010 American Control Conference. - 0743-1619. - 9781424474264 ; , s. 2164-2169
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a transfer function parameter identification method, applicable to SISO systems of any order. Parameter identification is posed as a (non-convex) squared output error minimization problem, numerically solved utilizing Newton-Raphson iteration with back tracking line search. Focus lies on computing the cost function gradient and Hessian with respect to the parameter vector and on finding a feasible start point. The method is demonstrated for FOTD model identification. A modified relay non-linearity is utilized in order to obtain most input signal energy at a predefined phase, without a priori system information. The identification method is evaluated on a batch of common process industry processes. Finally, conclusions and suggestions on future work are provided.
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| 35. |
- Sou, Kin Cheong, et al.
(författare)
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A Singular Value Decomposition Based Closed Loop Stability Preserving Controller Reduction Method
- 2010
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Ingår i: 2010 AMERICAN CONTROL CONFERENCE. - 0743-1619. - 9781424474264 ; , s. 1079-1084
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Konferensbidrag (refereegranskat)abstract
- In this paper a controller reduction method whichpreserves closed loop stability is described. A Lyapunov inequalitybased sufficient condition is proposed in the search ofthe reduced controller. The reduced controller leads to a stableclosed loop system with guaranteed approximation quality. Furthermore,the proposed problem can be formulated as a matrixapproximation problem which can be solved efficiently usingsingular value decomposition. Numerical application examplesare shown in the end to evaluate the generality of the proposedreduction method.
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| 36. |
- Yang, Tao, et al.
(författare)
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Output synchronization for heterogeneous networks of discrete-time introspective right-invertible agents with uniform constant communication delay
- 2013
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Ingår i: 2013 American Control Conference (ACC). - : American Automatic Control Council. - 9781479901777 ; , s. 516-521
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Konferensbidrag (refereegranskat)abstract
- In this paper, we consider synchronization problems for heterogeneous networks of introspective, right-invertible, discrete-time linear agents with uniform constant communication delay. We first design decentralized controllers for solving the output synchronization problem for a set of network topologies under arbitrary bounded delay. We then apply the proposed scheme to solve the formation problem with arbitrarily given formation vectors. Finally, we consider the output regulation problem, where the output of each agent has to track an a prior specified reference trajectory, generated by an exosystem. In this case, we assume that the common root agent has access to its own output relative to the reference trajectory. We then solve the problem for a set of network topologies with delay whose upper bound depends exosystem and some characteristic of network topologies.
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