| 1. |
- Bao, Lei, et al.
(author)
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Encoder-decoder design for event-triggered feedback control over bandlimited channels
- 2006
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In: 2006 American Control Conference. - : IEEE. - 1424402093 ; , s. 4183-4188
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Conference paper (peer-reviewed)abstract
- Bandwidth limitations and energy constraints set severe restrictions on the design of control systems that utilize wireless sensor and actuator networks. It is common in these systems that a sensor node needs not be continuously monitored, but communicates to the controller only at certain instances when it detects a disturbance event. In this paper, such a scenario is studied and particular emphasis is on efficient utilization of the shared communication resources. Encoder-decoder design for an event-based control system with the plant affected by pulse disturbances is considered. A new iterative procedure is proposed which can jointly optimize encoder-decoder pairs for a certainty equivalent controller. The goal is to minimize a design criterion, in particular, a linear quadratic cost over a finite horizon. The algorithm leads to a feasible design of time-varying non-uniform encoder-decoder pairs. Numerical results demonstrate significant improvements in performance compared to a system using uniform quantization.
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| 2. |
- Glad, Torkel, 1947-, et al.
(author)
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Hamilton-Jacobi Equations for Nonlinear Descriptor Systems
- 2006
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In: Proceedings of the 2006 American Control Conference. - 1424402107 - 1424402093 ; , s. 1027-1031
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Conference paper (peer-reviewed)abstract
- Optimal control problems for nonlinear descriptor systems are considered. Anapproach where the descriptor system is conceptually reduced to a state spaceform is compared to an approach where the Hamilton-Jacobi equation is directly formulated for the descriptor system. The two approaches are shown to give essentially the same systems of equations to be solved. A certain unknown function is present only in the second approach but is shown to be computable from the quantities common to both approches.
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| 3. |
- Jönsson, Ulf
(author)
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A sector condition for local robustness of limit cycles
- 2006
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In: 2006 American Control Conference, Vols 1-12. - 1424402093 ; , s. 5014-5019
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Conference paper (peer-reviewed)abstract
- Robustness of periodic oscillations in autonomous feedback systems are considered for systems with separable nonlinearities. Local quadratic separation of the nonlinear dynamics from the linear part of the dynamics is used to characterize a set of systems that exhibit periodic oscillation in a bounded frequency and amplitude range. The main analysis condition can be formulated as a feasibility problem for linear matrix inequalities.
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| 4. |
- Rotkowitz, Michael
(author)
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Information structures preserved under nonlinear time-varying feedback
- 2006
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In: 2006 American Control Conference, Vols 1-12. - 1424402093 ; , s. 4207-4212
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Conference paper (peer-reviewed)abstract
- The problem of parameterizing all stabilizing controllers subject to constraints is considered. A new condition relating the plant and the constraints is introduced, and it is shown that when it holds, the constraints are invariant under feedback. There is no assumption of linearity or time-invariance on either the plant or the admissible controllers, only causality. There is also no assumption that the constraint set be a subspace, only that it is closed. The results hold in continuous time or discrete time. When the condition holds, we then obtain a parameterization of all stabilizing controllers subject to the specified constraints, which is a convex parameterization as long as the desired constraint set is convex.
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| 5. |
- Sjöberg, Johan, 1978-, et al.
(author)
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Computing the Controllability Function for Nonlinear Descriptor Systems
- 2006
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In: Proceedings of the 2006 American Control Conference. - 1424402107 - 1424402093 ; , s. 1027-1031
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Conference paper (peer-reviewed)abstract
- The computation of the controllability function for nonlinear descriptor systems is considered. Three different methods are derived. The first method is based on the necessary conditions for optimality from the Hamilton-Jacobi-Bellman theory for descriptor systems. The second method uses completion of squares to find the solution. The third method gives a series expansion solution, which with a finite number of terms can serve as an approximate solution.
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| 6. |
- Stocks, Mikael, et al.
(author)
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Experimental validation of idealized two-axis models of faulty induction machines
- 2006
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In: 2006 American Control Conference. - Piscataway, NJ : IEEE Communications Society. - 1424402093 - 1424402107 ; , s. 1845-1850
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Conference paper (peer-reviewed)abstract
- In this paper, two dynamical models of the induction machine (IM) subject to electrical faults in the stator and rotor respectively are validated against experimental data. The considered stator faults are inter-turn short circuit in one of the phases and increased phase winding resistance. The rotor model is validated against an IM with one broken rotor bar, but otherwise healthy. The model parameters are estimated by the Gauss-Newton method and the obtained estimates are compared and discussed. The validation results show, for each of the considered faults, very good agreement between simulations and experiments. This makes the models promising in various applications involving asymmetric IM such as fault tolerant motor drives and motor condition monitoring.
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