Abstract-This paper extends the LTI anti-windup compensator scheme proposed in [6] to linear parameter-varying (LPV) systems. Following the MRAW concept, the dynamical part of the compensator is formed by the exact copy of the plant. The design procedure is thus simplified to the construction of a parameter-dependent state feedback, which stabilizes the plant's copy and determines the performance and the domain of applicability of the compensator. To decrease the conservatism, the presented method applies parameter-dependent Lyapunov function and embeds the saturation (dead-zone) in a parameterdependent sector. The design is formulated as an LMI-based convex optimization problem.The paper also investigates the possibility of eliminating certain free variables in order to reduce the complexity of the synthesis procedure. It is shown that an elimination procedure similar to that in [6] can be carried out, but with LPV systems the reconstruction of the compensator gain is not so straightforward. To overcome the difficulty a novel method is proposed, which is based on a closed formula parameterizing all solutions of the synthesis LMIs. Both of the fully parameterized and the reduced complexity syntheses are presented and their properties are analyzed. The applicability of the methods is demonstrated on a simple LPV plant.
I. INTRODUCTIONControl input limitations are always present in real physical systems. If the controller is designed irrespective of these limitations, the later appearance of a saturation may cause undesired behavior in the closed loop: it leads to performance degradation or even instability. This effect is called controller windup.One possible way to minimize the undesired effects of controller windup is using an anti-windup compensator. The concept is simple ([17], [21]): the controller is designed irrespective of the saturation and then a a static or dynamic compensator is designed so that the following three criteria are fulfilled: (1) the closed loop is (locally) stable; (2) if there is no saturation, the nominal performance is guaranteed; (3) in case of saturation the system is driven by the compensator so that the signals leave the saturating domain and the nominal performance is recovered as quickly as possible.There are two large groups of model-based anti-windup solutions ([21], [8]): Direct Linear Anti-Windup (DLAW) and Model Recovery Anti-Windup (MRAW) methods. The direct method considers the unconstrained feedback loop as a special plant and the compensator as a special controller. The compensator construction is then reformulated as a control design problem for which the existing synthesis algorithms -LTI [12] or LPV [2] -can be easily adapted. Since the plant in the compensator design consists of the original plant and the controller, the LMIs are formulated in the extended (plant+controller dimensional) space. If the plant is a high dimensional system and the unconstrained controller inherits this complexity, the optimization problem may become large and computationally demanding. O...