| 1. |
- Andersson, Martin, et al.
(författare)
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Simulation of Wireless Networked Control Systems
- 2005
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Ingår i: Proceedings of the 44th IEEE Conference on Decision and Control and the 2005 European Control Conference. - 0780395689 ; , s. 476-481
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Konferensbidrag (refereegranskat)abstract
- Embedded systems are becoming increasingly networked and are deployed in application areas that require close interaction with their physical environment. Examples include distributed mobile agents and wireless sensor/actuator networks. The complexity of these applications make co-simulation a necessary tool during system development. This paper presents a simulation environment that facilitates simulation of computer nodes and communication networks interacting with the continuous-time dynamics of the real world. Features of the simulator include interrupt handling, task scheduling, wired and wireless communication, local clocks, dynamic voltage scaling, and battery-driven operation. Two simulation case studies are presented: a simple communication scenario and a mobile robot soccer game.
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| 2. |
- Byrnes, C. I., et al.
(författare)
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The covariance extension equation revisited
- 2005
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Ingår i: Proceedings of the 44th IEEE Conference on Decision and Control, and the European Control Conference, CDC-ECC '05. - 0780395689 - 9780780395688 ; , s. 7924-7930
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Konferensbidrag (refereegranskat)abstract
- In this paper we study the steady state form of a discrete-time matrix Riccati-type equation, connected to the rational covariance extension problem and to the partial stochastic realization problem. This equation, however, is non-standard in that it lacks the usual kind of definiteness properties which underlie the solvability of the standard Riccati equation. Nonetheless, we prove the existence and uniqueness of a positive semidefinite solution. We also show that this equation has the proper geometric attributes to be solvable by homotopy continuation methods, which we illustrate in several examples.
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| 3. |
- Fujioka, H., et al.
(författare)
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Sampled-data H∞ control design for a class of PWM systems
- 2005
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Ingår i: Proceedings of the 44th IEEE Conference on Decision and Control, and the European Control Conference, CDC-ECC '05. - 0780395689 - 9780780395688 - 0780395670 ; , s. 4499-4504
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Konferensbidrag (refereegranskat)abstract
- Robust control of a class of switched dynamical systems is considered. The switching is controlled by pulse-width modulation (PWM). This idea is used, for example, in power electronics for power conversion. The class of systems considered includes digitally controlled power converters of many different types. The traditional approach to control design for power converters rely on an averaged model that ignores the high frequency behavior and the inherent time delay due to sampling. In contrast, the method presented here is based on a sampled-data model which takes the switched nature of the system into account. The sampled-data model is approximated by a linear quadratic model to which sampled-data H∞ theory can be extended. The approach is applied to a bidirectional boost converter which is subjected to a large load disturbance.
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| 4. |
- Gerencsér, Laszlo, et al.
(författare)
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Adaptive input design in system identification
- 2005
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Ingår i: 2005 44TH IEEE CONFERENCE ON DECISION AND CONTROL & EUROPEAN CONTROL CONFERENCE. - Seville. - 0780395689 - 9780780395688 - 0780395670 ; , s. 4988-4993
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Konferensbidrag (refereegranskat)abstract
- Recently there have been significant developments in re-casting experiment design problems in system identification as convex optimization problems. The practical implementation of these methods is hampered by the fact that typically the "data" in the optimization problem depend on the to be identified system. In this contribution we propose an adaptive certainty equivalence solution based on a recursively identified model. The input design is adapted by taking one Newton step using data from the last identified model.
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| 5. |
- Haugwitz, Staffan, et al.
(författare)
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Anti-windup in mid-ranging control
- 2005
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Ingår i: Proceedings of the 44th IEEE Conference on Decision and Control and the 2005 European Control Conference. - 0780395689 ; , s. 7570-7575
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Konferensbidrag (refereegranskat)abstract
- The implementation of anti-windup methods in mid-rangingcontrol needs further attention. It is demonstrated how use of standard anti-windup schemes may give unnecessary performance degradation during saturation. The problem isillustrated for two separate systems, control of oxygen concentration in a bio-reactor and temperature controlof a cooling system. In the paper, guidelines are derived for how to design the standard anti-windup scheme to recover performance. As an alternative a modified anti-windup scheme for mid-ranging control is presented that minimizes the performance degradation during saturation.
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| 6. |
- Henriksson, Dan, et al.
(författare)
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Optimal On-line Sampling Period Assignment for Real-Time Control Tasks Based on Plant State Information
- 2005
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Ingår i: Proceedings of the 44th IEEE Conference on Decision and Control and the 2005 European Control Conference. - 0780395689 ; , s. 4469-4474
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Konferensbidrag (refereegranskat)abstract
- The paper presents a feedback scheduling strategy for multiple control tasks that uses feedback from the plant states to distribute the computing resources optimally among the tasks. Linear-quadratic controllers are analyzed, and expressions relating the expected cost to the sampling period and the plant state are derived and used for on-line sample-rate adjustments. In the case of minimum-variance control of multiple integrator processes, an exact expression for the optimal sampling periods is obtained. For the general case, an on-line optimization procedure is developed. The approach is exemplified on a set of controllers for first-order systems. The issues of computational delay and the choice of the feedback scheduler period are also discussed.
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| 7. |
- Möller, Niels, et al.
(författare)
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Using radio network feedback to improve TCP performance over cellular networks
- 2005
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Ingår i: Proceedings of the 44th IEEE Conference on Decision and Control, and the European Control Conference 2005. - : IEEE. - 0780395689 ; , s. 7434-7439
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Konferensbidrag (refereegranskat)abstract
- A new control structure is proposed to improve user experience of wireless Internet. Information on radio bandwidth and queue length available in the radio network controller (RNC), close to the base station, is used in a proxy that resides between the Internet and the cellular system. The control algorithm in the proxy sets the window size according to event-triggered information on radio bandwidth changes and time-triggered information on the queue length of the RNC. A stability analysis of the hybrid control system is performed. In a number of realistic use cases evaluated in ns-2, the new control structure is compared to a nominal one that employs end-to-end TCP Reno. It is shown that the proposed solution reduces the time to serve users, increases the radio link utilization, and decreases the required buffer size in the RNC.
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| 8. |
- Prajna, S., et al.
(författare)
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On Model Reduction of Polynomial Dynamical Systems
- 2005
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Ingår i: 2005 44th IEEE Conference on Decision and Control & European Control Conference, Vols 1-8. - 0780395689 ; , s. 1666-1671
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Konferensbidrag (refereegranskat)abstract
- In this paper, we develop a computational method for model reduction of polynomial dynamical systems. This is achieved using sum of squares relaxations on certain Lyapunov inequalities, which are the nonlinear counterparts of the Lyapunov controllability and observability linear matrix inequalities for linear systems. In our model reduction procedure, we use notions of balanced realization and balanced truncation for a polynomial model. In addition, we derive an a-priori error bound on the approximation error for balanced truncation.
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| 9. |
- Rantzer, Anders
(författare)
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On Approximate Dynamic Programming in Switching Systems
- 2005
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Ingår i: Proceedings of the 44th IEEE Conference on Decision and Control and the 2005 European Control Conference. - 0780395689 ; , s. 1391-1396
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Konferensbidrag (refereegranskat)abstract
- In order to simplify computational methods based on dynamic programming, an approximative procedure based on upper and lower bounds of the optimal cost was recently introduced. The convergence properties of this procedure are analyzed in this paper. In particular, it is shown that the computational effort in finding an approximately optimal control law by relaxed value iteration is related to the polynomial degree that is needed to approximate the optimal cost. This gives a rigorous foundation for the claim that the search for optimal control laws requires complex computations only if the optimal cost function is complex. A computational example is given for switching control on a graph with 60 nodes, 120 edges and 30 continuous states.
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| 10. |
- Shiriaev, Anton, et al.
(författare)
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Output feedback stabilization of the Moore-Greitzer compressor model
- 2005
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Ingår i: 2005 44th IEEE Conference on Decision and Control & European Control Conference, Vols 1-8. - 0780395670 - 0780395689 ; , s. 1102-1107
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Konferensbidrag (refereegranskat)abstract
- This paper presents a number of facts related to the output feedback stabilization of the Moore-Greitzer compressor model. We show that quadratic feedback stabilization of the surge subsystem of the three-state Moore-Greitzer compressor model, which ensures absence of additional equilibria and cycles in the closed-loop system augmented with stall dynamics, implies convergence of all solutions to the unique equilibrium at the origin. Then some steps in developing such output feedback controller for surge subsystem are discussed.
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| 11. |
- Shiriaev, Anton S, et al.
(författare)
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Periodic motion planning for virtually constrained (hybrid) mechanical systems
- 2005
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Ingår i: 2005 44th IEEE conference on decision and control & European control conference, vols 1-8. - New York : IEEE conference proceedings. - 0780395670 - 0780395689 ; , s. 4035-4040
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Konferensbidrag (refereegranskat)abstract
- The paper presents sufficient and almost necessary conditions for the presence of periodic solutions for zero dynamics of virtually constrained under-actuated Euler-Lagrange system. This result is further extended to detect periodic solutions for a class of hybrid systems in the plane and analyze their orbital stability and instability. Illustrative examples are given.
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| 12. |
- Wernrud, Andreas, et al.
(författare)
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On approximate policy iteration for continuous-time systems
- 2005
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Ingår i: Proceedings of the 44th IEEE Conference on Decision and Control and the 2005 European Control Conference. - 0780395689 ; , s. 1453-1458
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Konferensbidrag (refereegranskat)abstract
- We propose a new algorithm for feedback nonlinear synthesis. The algorithm computes suboptimal solutions, with bounds on suboptimality, to the Hamilton-Jacobi-Bellman equation. For systems that are modeled with polynomials the computations can be done efficiently via semidefinite programming. To illustrate the strength of the proposed method, we computesmooth stabilizing feedback controllers for several problems.
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