| 1. |
- Bengtsson, Johan, et al.
(author)
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Modeling of HCCI Engine Combustion for Control Analysis
- 2004
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In: Proceedings 43rd IEEE Conference on Decision and Control. - 0191-2216. - 0780386825 ; 2, s. 1682-1687
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Conference paper (peer-reviewed)abstract
- Operation of homogeneous charge compression ignition (HCCI) enginesare very sensitive to timing variations in the combustion of theair-fuel charge mixture and require precise control of the ignitioninstant to run properly. It is therefore essential to understand thecharacteristics of timing variations under various operatingconditions in order to find suitable control strategies. This paperpresents a first step towards the construction of an HCCI enginemodel aimed at studies on timing control strategies. The goal is to(qualitatively) reproduce the timing effects that may be observed ona real engine. The proposed model includes a lumped chemical kineticmodel for hydrocarbon fuels to predict autoignition. Single-cyclesimulations are compared with experimental results from a realengine to validate the model.
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| 2. |
- Calugi, Francesco, et al.
(author)
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An Adaptive Observer for Dynamical Ship Position Control Using Vectorial Observer Backstepping
- 2003
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In: Proceedings. 42nd IEEE Conference on Decision and Control, 2003.. - 0191-2216. - 0780379241 ; 4, s. 3262-3267
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Conference paper (peer-reviewed)abstract
- In this paper, we propose an adaptive observer for dynamically positioned ships, that can be used together with the controller shown by Fossen and Grovlen, to design an observer-based adaptive control scheme. The resulting closed-loop system is globally asymptotically stable with respect to the ship positions and velocities, and globally stable with respect to adaptation to unknown parameters. A discrete-time approximation scheme is presented.
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| 3. |
- Christiansson, Anna-Karin, 1947-, et al.
(author)
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Continuous-, discrete- and sampled-data- H∞ˆž control - a unified framework
- 2000
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In: IEEE Proceedings. - 0191-2216. ; 2, s. 1936-1941
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Journal article (peer-reviewed)abstract
- We present a unified and general framework for H∞-control in both continuous time, discrete time and combinations of these. The general result is a hybrid continuous-/discrete-time H∞ˆž-controller. Using a compact hybrid notation, the work shows a close relationship between the continuous-and discrete-time solutions. In fact, the pure continuous and discrete time equations may be obtained as two similar interpretations of the general result. There are no assumptions made on certain system matrices being zero or normalised, e.g. D11 = 0. The method is Riccati equation (RE) based, and it is shown how the continuous REs can be "lifted" into discrete ones reflecting the system behaviour during the period. Typical applications are control of continuous-time or discrete-time periodic systems, as well as multirate and sampled-data control, including mixed continuous and sampled-data measurements.
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| 4. |
- Como, Giacomo, et al.
(author)
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Robust distributed routing in dynamical flow networks
- 2011
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In: 2011 50th IEEE Conference on Decision and Control and European Control Conference, CDC-ECC 2011. - 0191-2216. - 9781612848006 ; , s. 6290-6295
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Conference paper (peer-reviewed)abstract
- Robustness of distributed routing policies is studied for dynamical flow networks, with respect to adversarial disturbances that reduce the link flow capacities. A dynamical flow network is modeled as a system of ordinary differential equations derived from mass conservation laws on a directed acyclic graph with a single origin-destination pair and a constant inflow at the origin. Routing policies regulate the way the inflow at a non-destination node gets split among its outgoing links as a function of the current particle density, while the outflow of a link is modeled to depend on the current particle density on that link through a flow function. The robustness of distributed routing policies is evaluated in terms of the network's weak resilience, which is defined as the infimum sum of link-wise magnitude of disturbances under which the total inflow at the destination node of the perturbed dynamical flow network is positive. The weak resilience of a dynamical flow network with arbitrary routing policy is shown to be upper-bounded by the network's min-cut capacity, independently of the initial flow conditions. Moreover, a class of distributed routing policies that rely exclusively on local information on the particle densities, and are locally responsive to that, is shown to yield such maximal weak resilience. These results imply that locality constraints on the information available to the routing policies do not cause loss of weak resilience.
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| 7. |
- Giselsson, Pontus
(author)
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Execution time certification for gradient-based optimization in model predictive control
- 2012
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In: [Host publication title missing]. - 0191-2216. ; , s. 3165-3170
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Conference paper (peer-reviewed)abstract
- We consider model predictive control (MPC) problems with linear dynamics, polytopic constraints, and quadratic objective. The resulting optimization problem is solved by applying an accelerated gradient method to the dual problem. The focus of this paper is to provide bounds on the number of iterations needed in the algorithm to guarantee a prespecified accuracy of the dual function value and the primal variables as well as guaranteeing a prespecified maximal constraint violation. The provided numerical example shows that the iteration bounds are tight enough to be useful in an inverted pendulum application.
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| 8. |
- Gros, Sébastien, 1977, et al.
(author)
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A Real-time MHE and NMPC Scheme for Wind Turbine Control
- 2013
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In: 52nd IEEE Conference on Decision and Control, CDC 2013, Florence, Italy, 10-13 December 2013. - 0191-2216. ; , s. 1017-1022
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Conference paper (peer-reviewed)abstract
- Among the several problems arising in the Airborne Wind Energy paradigm, an essential one is the control of the tethered airfoil trajectory during power generation. Tethered flight is a fast, strongly nonlinear, unstable and constrained process, motivating control approaches based on fast Non-linear Model Predictive Control. In this paper, a computationally efficient model is proposed, based on Differential-Algebraic equations. A control scheme based on Nonlinear Model Predictive Control (NMPC) and an estimator based on Moving Horizon Estimation (MHE) is proposed to handle the wind turbulences. In order to make a real-time application of Non-linear Model Predictive Control possible, a Real-Time Iteration scheme is proposed.
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| 9. |
- Gros, Sébastien, 1977
(author)
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An Economic NMPC Formulation for Wind Turbine Control
- 2013
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In: 52nd IEEE Conference on Decision and Control, CDC 2013, Florence, Italy, 10-13 December 2013. - 0191-2216. - 9781467357173
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Conference paper (peer-reviewed)abstract
- Model Predictive Control (MPC) is a strong candidate for the control of large Multi-MegaWatt Wind Turbine Generators. Several MPC and some Nonlinear MPC scheme have been proposed in the literature, based on reference-tracking objective functions. While the resulting schemes offer very promising results, the difficulty of tuning a reference-tracking NMPC scheme for performance is likely to be a hindrance to the industrial success of NMPC-based WTG control. Because they directly maximize the system performance, economic NMPC schemes are more straightforward to tune. Economic NMPC schemes present, however, some known difficulties that are a serious obstacle to their real-time deployment. This paper presents an economic NMPC formulation for maximizing the generated power of wind turbine generators, which does not suffer from such difficulties. The relationship between the proposed and more classical reference-tracking approaches is formally established.
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| 10. |
- Grussler, Christian, et al.
(author)
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A Symmetry Approach for Balanced Truncation of Positive Linear Systems
- 2012
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In: IEEE Control Systems Society Conference 2012, Maui. - 0191-2216. ; , s. 4308-4313
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Conference paper (peer-reviewed)abstract
- We consider model order reduction of positive linear systems and show how a symmetry characterization can be used in order to preserve positivity in balanced truncation. The reduced model has the additional feature of being symmetric.
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