| 1. |
- Almér, Stefan, et al.
(författare)
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Hybrid control techniques for switched-mode DC-DC converters part I : The step-down topology
- 2007
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Ingår i: 2007 American Control Conference. - : IEEE. - 1424409888 - 9781424409884 ; , s. 5450-5457
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Konferensbidrag (refereegranskat)abstract
- Several recent techniques from hybrid and optimal control are evaluated on a power electronics benchmark problem. The benchmark involves a number of practically interesting operating scenarios for a fixed-frequency synchronous step-down dc-dc converter. The specifications are defined such that good performance only can be obtained if the switched and nonlinear nature of the problem is respected during the design phase.
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| 2. |
- Beccuti, A. G., et al.
(författare)
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Hybrid control techniques for switched-mode DC-DC converters part II : The step-up topology
- 2007
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Ingår i: 2007 American Control Conference, Vols 1-13. - 1424409888 - 9781424409884 ; , s. 5464-5471
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Konferensbidrag (refereegranskat)abstract
- Several recent techniques from hybrid and optimal control are evaluated on a power electronics benchmark problem. The benchmark involves a number of practically interesting operating scenarios for a fixed-frequency step-up dc-dc converter. The specifications are defined such that good performance can only be obtained if the switched and nonlinear nature of the problem is respected during the design phase.
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| 3. |
- Gattami, Ather, et al.
(författare)
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Minimax Team Decision Problems
- 2007
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Ingår i: ; , s. 4333-4338, s. 766-771
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Konferensbidrag (refereegranskat)abstract
- We consider the problem of distributed decision making in a quadratic game between a "team" of players and nature. Each player has limited information that could be different from the other players in the team. We show that if there is a solution to the minimax team problem, then the linear policies are optimal, and we show how to find the linear optimal solution by solving a linear matrix inequality. The result is used to solve the distributed H infinity control problem. It shows that the information structure restricted to exchange information with neighbours only, is enough to obtain a linear optimal feedback law.
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| 4. |
- Kao, C. -Y, et al.
(författare)
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Characterization of robust stability of a class of interconnected systems
- 2007
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Ingår i: American Control Conference, 2007. ACC '07. - 1424409888 - 9781424409884 ; , s. 784-789
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Konferensbidrag (refereegranskat)abstract
- We consider robust stability analysis of a class of spatially interconnected systems. The individual subsystems may be different but they are assumed to share some properties that can be characterized by an integral quadratic constraint. The main contribution of the paper is to show that, for the case where the network interconnection matrix is normal, (robust) stability verification can be simplified to a simple problem of checking the location of the eigenvalues of the interconnection matrix. Most interestingly, we also identify a class of networks for which this characterization on eigenvalues is necessary and sufficient for robust stability.
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| 5. |
- Bao, Lei, et al.
(författare)
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A scheme for joint quantization, error protection and feedback control over noisy channels
- 2007
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Ingår i: 2007 AMERICAN CONTROL CONFERENCE, VOLS 1-13. - : IEEE. - 9781424409884 ; , s. 2456-2461
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Konferensbidrag (refereegranskat)abstract
- We study a closed-loop scalar control system with feedback transmitted over a discrete noisy channel. For this problem, we propose a joint design of the state measurement quantization, protection against channel errors, and control. The goal is to minimize a linear quadratic cost function over a finite horizon. In particular we focus on a special case where we verify that certainty equivalence holds, and for this case we design joint source-channel encoder and decoder/estimator pairs. The proposed algorithm leads to a practically feasible design of time-varying non-uniform quantization and control. Numerical results demonstrate the promising performance obtained by employing the proposed iterative optimization algorithm.
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| 6. |
- Dahl, Ola, et al.
(författare)
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Nonlinear and Adaptive Observers for Perspective Dynamic Systems
- 2007
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Ingår i: Proceedings American Control Conference. - : IEEE. - 0743-1619. - 9781424409884 ; , s. 2230-2235
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Konferensbidrag (refereegranskat)abstract
- Estimation of 3D structure and motion from 2D images in computer vision systems can be performed using a dynamic system, often referred to as a perspective dynamic system. This paper presents a novel parametrization of the nonlinear perspective dynamic system, from which different estimators for rigid body structure as well as motion can be derived in a straightforward manner. The parametrization allows a structure estimator to be formulated as a nonlinear observer which estimates 3D position, assuming knowledge of angular and linear velocities. The observer performance is demonstrated using simulation examples, where it is also shown how a time scaling parameter can be used to tune the transient response. The parametrization also allows a motion estimator to be formulated as an adaptive observer, estimating angular velocity and 3D position assuming knowledge of the linear velocity. This is demonstrated by deriving an estimator and illustrating its performance in a simulation example. The presented investigations and simulations indicate that the parametrization has a potential for future development of estimators for structure as well as motion in perspective dynamic systems, and for the investigation of similarities and differences in comparison to discrete, projective geometry based, methods.
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| 7. |
- Dahl, Ola, et al.
(författare)
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On Observer Error Linearization for Perspective Dynamic Systems
- 2007
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Ingår i: Proceedings American Control Conference. - : IEEE. - 1424409888
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Konferensbidrag (refereegranskat)abstract
- State estimation in perspective dynamic systems can be performed using different kinds of nonlinear observers. In this paper we investigate observer error linearization for perspective dynamic systems, where the goal is to find a coordinate transformation that results in a system for which a linear observer can be constructed. We present preliminary results in this direction, showing that such linearizing coordinate transformations indeed exist, subject to certain constraints on the angular and linear velocities. Specifically, it is shown that in many situations a linearizing coordinate transformation can be found only when additional states are added to the original system. This results in what is referred to as dynamic observer error linearization. Our investigations further provide additional insight into observability issues for perspective dynamic systems by showing how an observability condition can be interpreted in terms of the focus of expansion, and how the condition is related to the derivation of appropriate coordinate transformations.
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| 8. |
- Nilsson, Magnus, 1978, et al.
(författare)
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Nonlinear Adaptive Feedforward in a Two-Degrees-of-Freedom Controller
- 2007
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Ingår i: American Control Conference. - 0743-1619. - 1424409888 ; , s. 3979-3984
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Konferensbidrag (refereegranskat)abstract
- An adaptive feedforward steady-state gain in a two-degrees-of-freedom controller for a nonlinear SISO plant is investigated. The examination of a less complicated structure gives hints to how an update law may be constructed in the nonlinear case. Stability is shown in the simpler case for an update law based on an estimation error using projection, and simulations show that Altering may lead to improved performance. By using an adaptive feedforward function inspired by gain-scheduling techniques, a simulation example for the nonlinear structure is also shown. The conclusions are that the scheme has potential but that more research is needed for the nonlinear setup.
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| 9. |
- Rojas, Cristian R., 1980-, et al.
(författare)
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A Receding Horizon Algorithm to Generate Binary Signals with a Prescribed Autocovariance
- 2007
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Ingår i: 2007 AMERICAN CONTROL CONFERENCE, VOLS 1-13. - 9781424409884 ; , s. 122-127
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Konferensbidrag (refereegranskat)abstract
- Optimal test signals are frequently specified in terms of their second order properties, e.g. autocovariance or spectrum. However, to utilize these signals in practice, one needs to be able to produce realizations whose second order properties closely approximate the prescribed properties. Of particular interest are binary waveforms since they have the highest form-factor in the sense that they achieve maximal energy for a given amplitude. In this paper we utilize ideas from model predictive control to generate a binary waveform whose sampled autocovariance is as close as possible to some prescribed autocovariance. Several simulated examples are presented verifying the veracity of the algorithm. Also, a proof of convergence is given for the special case of bandlimited white noise. This proof is based on expressing the system in the form of a switched linear system.
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| 10. |
- Sandberg, Henrik, et al.
(författare)
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Frequency-Weighted Model Reduction with Applications to Structured Models
- 2007
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Ingår i: 2007 AMERICAN CONTROL CONFERENCE, VOLS 1-13. - 9781424409884 ; , s. 941-946
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Konferensbidrag (refereegranskat)abstract
- In this paper, a frequency-weighted extension of a recently proposed model reduction method for linear systems is presented. The method uses convex optimization and can be used both with sample data and exact models. We also obtain bounds on the frequency-weighted error. The method is combined with a rank-minimization heuristic to approximate multi- input-multi-output systems. We also present two applications - environment compensation and simplification of interconnected models - where we argue the proposed methods are useful.
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