The paper addresses the problem of analysis and static output feedback control synthesis for strict quadratic dissipativity of linear time-invariant systems with state-space symmetry. As a particular case of dissipative systems, we consider the mixed H∞ and positive real performance criterion and we develop an explicit expression for calculating the H∞ norm of these systems. Subsequently, an explicit parametrization of the static output feedback control gains that solve the mixed H∞ and positive real performance problem is obtained. Computational examples demonstrate the use and computational advantages of the proposed explicit solutions.

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Operation of wind turbines in the full-load region mandates that the produced power is kept at a rated value to minimize structural loads and thereby reduce fatigue damage. This is usually achieved by pitching the rotor blades in order to limit the aerodynamic torque in high wind speeds. The pitch actuators usually present a hard constraint in terms of the amplitude and rate of saturation. In this paper, we propose a method to address pitch actuator amplitude and rate saturation by designing anti-windup controllers in the linear parameter-varying framework. The proposed design method guarantees the closedloop system stability and a prescribed level of performance while it decreases the pitch activity for regulating the generated power to the nominal power during sudden wind gusts. The anti-windup controller designed to minimize the H 1 norm of the closed-loop system is gain-scheduled on the basis of the operating condition of the turbine, as well as the states of amplitude and rate saturation of the pitch actuator. The effectiveness of the proposed control design method is demonstrated using high-fidelity aeroelastic dynamic simulation tools.

Magneto-rheological (MR) dampers are a family of semi-active devices widely used for vibration attenuation in space and civil engineering structures. In this paper, we study the use of MR dampers for seismic protection of a model two-story structure in the presence of actuation saturation. A modified Bingham model is considered for linear parameter varying (LPV) modeling and control of the system. The main contribution of the paper is the design and experimental validation of a LPV anti-windup compensator to tackle the effect of actuator saturation on the control design performance. The designed LPV anti-windup control scheme is advantageous from the implementation standpoint because it can be considered as an addition to the existing control system. Experimental results demonstrate the ability of the design method to attenuate the effects of seismic excitation by controlling the MR damper and simultaneously avoid the adverse effects of actuator saturation by taking advantage of the designed anti-windup compensator and leading to savings in power consumption.