Publications (6)0 Total impact
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Article: Predictive Control for Polynomial Systems Subject to State and Input Constraints.
Automatisierungstechnik. 01/2011; 59:479-488. -
Conference Proceeding: MPC with one Free Control Action for Constrained LPV Systems.
Proceedings of the IEEE International Conference on Control Applications, CCA 2010, Yokohama, Japan, September 8-10, 2010; 01/2010 -
Chapter: Spacecraft Rate Damping with Predictive Control Using Magnetic Actuators Only
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ABSTRACT: A nonlinear model predictive control (NMPC) approach for rate damping control of a low Earth orbit satellite in the initial acquisition phase is proposed. The only available actuators are magnetic coils which impose control torques on the satellite in interaction with the Earth’s magnetic field. In the initial acquisition phase large rotations and high angular rates, and therefore strong nonlinearities must be dealt with. The proposed NMPC method, which is shown to guarantee closed-loop stability, efficiently reduces the kinetic energy of the satellite while satisfying the constraints on the magnetic actuators. Furthermore, due to the prediction of future trajectories, the negative effect of the well-known controllability restriction in magnetic spacecraft control is minimized. It is shown via a simulation example that the obtained closed-loop performance is improved when compared to a classical P-controller.05/2009: pages 511-520; -
Chapter: Enlarging the Terminal Region of NMPC with Parameter-Dependent Terminal Control Law
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ABSTRACT: Nominal stability of a quasi-infinite horizon nonlinear model predictive control (QIH-NMPC) scheme is obtained by an appropriate choice of the terminal region and the terminal penalty term. This paper presents a new method to enlarge the terminal region, and therefore the domain of attraction of the QIH-NMPC scheme. The proposed method applies a parameter-dependent terminal controller. The problem of maximizing the terminal region is formulated as a convex optimization problem based on linear matrix inequalities. Compared to existing methods using a linear time-invariant terminal controller, the presented approach may enlarge the terminal region significantly. This is confirmed via simulations of an example system.05/2009: pages 69-78; -
Article: Offline NMPC for continuous-time systems using sum of squares
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ABSTRACT: An offline nonlinear model predictive control (NMPC) approach for continuous time nonlinear systems sub-ject to input and state constraints is presented. The approach deals with nonlinear systems which can be represented by polynomial parameter-varying systems. Since the applicability of NMPC is often limited by the speed at which an optimization problem can be solved online, we propose an NMPC scheme with drastically reduced online computational burden. The basic idea involves the offline computation of nested invariant sets and associated feedback laws by solving a convex optimiza-tion problem subject to sum of squares (SOS) constraints via semidefinite programming (SDP). Online, a search algorithm is executed to determine the feedback law suitable for the current state. The resulting offline NMPC controller guarantees stability and constraint satisfaction. Its applicability and effectiveness is shown by means of simulation of an example system. -
Article: Stability analysis of periodically time-varying systems using periodic Lyapunov functions
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ABSTRACT: This paper proposes a novel approach to stability analysis of discrete-time nonlinear periodi-cally time-varying systems. The contributions are as follows. Firstly, a relaxation of standard Lyapunov conditions is derived. This leads to a less conservative Lyapunov function that is required to decrease at every period rather than at each time instant. Secondly, for linear periodic systems with constraints, we show that compared to standard Lyapunov theory, the novel stability concept yields a larger estimate of the region of attraction. An example illustrates the effectiveness of the developed theory.
