An almost Anti-Windup scheme for plants with magnitude, rate and curvature saturation

peer reviewedWe address the anti-windup augmentation problem for plants with saturations on the magnitude, rate and curvature of the control input. To this aim, given an unconstrained closed-loop, we generate a slightly modified strictly proper controller for which the derivatives of the control signal are available and we solve the anti-windup problem for this modified control scheme (namely, an almost anti-windup for the original closed-loop). Based on this “almost” approach, we revisit an existing Model Recovery anti-windup solution for rate and magnitude saturated plants and then we extend the results to the case of rate, magnitude and curvature saturation, by providing a Model Recovery solution to this additional problem. An example illustrates the peculiarities and the effectiveness of the proposed solutions

Model based, gain-scheduled anti-windup control for LPV systems

peer reviewedIn this paper we show that a recently proposed technique for anti-windup control of exponentially unstable plants can be easily extended to solve the corresponding robust anti-windup problem for linear parameter varying systems, for which the time varying parameters are measured online. For this class of plants, it is shown that the proposed technique is minimally conservative with respect to the size of the resulting operating region: in particular, such a region is (up to an arbitrarily small quantity) exactly the largest set on which asymptotic stability can be guaranteed for the considered plant, for the given saturation level and uncertainty characteristics

Model recovery anti-windup for continuous-time rate and magnitude saturated linear plants

In this paper two approaches are given for anti-windup design for nonlinear control systems with linear plants subject to limitations both in the magnitude and the rate of variation of the control input. Both approaches are based on the so-called Model Recovery Anti-windup (MRAW) framework. The first approach is built by treating the rate+magnitude saturation as a single dynamic nonlinearity, while in the second one, the dynamic compensator dynamics is extended with extra states to treat the two saturations separately. Both approaches lead to global stability with exponentially stable plants and local stability in all other cases. For both approaches, stability and performance guarantees are proven, numerical recipes are given and the relative merits are comparatively highlighted on a simulation example.MIUR and PRIN project

Gain-scheduled, model-based anti-windup for LPV systems

The aim of this paper is to show that a recently proposed technique for anti-windup control of exponentially unstable plants can be easily extended to solve the corresponding robust anti-windup problem for linear parameter varying systems, for which the time varying parameters are measured online. The proposed technique is minimally conservative with respect to the size of the resulting operating region (which coincides, up to an arbitrarily small quantity, with the largest set on which asymptotic stability can be guaranteed for the considered plant with the given saturation level and uncertainty characteristics), and is not limited to plants having only small uncertainties or being open-loop stable.MIUR under PRIN project

Francis Equations vs Invariant Subspace Algorithm for Hybrid Output Regulation

In this paper, we deal with the output regulation problem for linear hybrid systems in the presence of unpredictable jumps, hence with arbitrary time domains. In particular we provide necessary and sufficient conditions for the solvability of the hybrid regulation problem, which non-trivially extend the classical conditions of regulation for LTI non-hybrid systems. Interestingly, differently from the latter, the former conditions are intrinsically nonlinear, since the dynamics of the interconnected system restricted to the error-zeroing invariant subspace may not be limited, as in the non-hybrid case, to those of the exosystem E. Then, we explore the relation between the discussed necessary and sufficient conditions and the constructive approach provided by the subspace invariant algorithm

Globally stabilizing quasi time-optimal control of planar saturated linear systems

peer reviewe

Output invisible control allocation with asymptotic optimization for nonlinear systems in normal form

We consider the problem of control allocation for weakly redundant nonlinear plant models, that is, input redundant systems possessing a maximum rank control distribution. Attention is focused on nonlinear models that admit a special global normal form, which subsumes the case of systems with globally-defined vector relative degree. It is shown how the availability of a set of suitably defined redundant input leads (under some technical conditions) to the definition of different static and dynamic strategies for steady-state optimization within a given set-point regulation problem