Gain-scheduled Output Feedback Research Articles

Humidity and Pressure Regulation in a PEM Fuel Cell Using a Gain-Scheduled Static Feedback Controller

In this paper, the pressure difference between the anode and cathode compartments of a polymer electrolyte membrane (PEM) fuel cell stack is regulated along with the anode and cathode humidities using an anode recirculation system. The pressure regulation requirement stems from membrane safety considerations. The regulation of average humidities in the two compartments is a necessary (although not a sufficient) requirement for stack water management. Two actuators in the anode recirculation system are considered, namely the dry hydrogen flow and the anode back pressure valve. These actuators are adjusted using a static output feedback controller that relies on pressure and humidity measurements on the anode side of the fuel cell stack. As the water mass dynamics and the characteristics of the water transport through the PEM are significantly different between subsaturated conditions (water is present only in vapor phase) and saturated conditions (liquid water along with water vapor), we show that the performance of the static output feedback controller with a fixed set of gains for subsaturated condition deteriorates significantly under a saturated condition. A gain-scheduled controller is therefore developed to compensate for a water-vapor saturated cathode condition. Analysis and simulation provide insights on some of the design and implementation issues for the gain-scheduled output feedback system.

Formula omitted] and [formula omitted] performance analysis and gain-scheduling synthesis for parameter-dependent systems

This paper focuses on quadratic performance analysis and output feedback gain-scheduling synthesis for parameter-dependent systems with linear fractional representations (LFRs). New quadratic H 2 and L 2 performance analysis results based on full-block multipliers are given. A novel gain-scheduling output feedback synthesis, which can be regarded as a natural extension of the loop shaping design procedure of McFarlane and Glover to parameter-dependent systems, is proposed. This gain-scheduling technique is computationally attractive and yields a simple and transparent control structure that can be easily implemented. Its effectiveness is illustrated on a benchmark missile autopilot example.

Robust and gain-scheduling control of LFT systems through duality and conjugate Lyapunov functions

In this paper, we study stability and performance properties of linear fractional transformation (LFT) parameter-dependent systems using duality theory and tools from convex analysis. A pair of conjugate functions, the convex hull and the maximum of a family of quadratic functions, are used for analysis and synthesis of LFT systems. Sufficient synthesis conditions for both robust state feedback and gain-scheduling output feedback control problems are formulated as a set of linear matrix inequalities (LMIs) with linear search over scalar variables. Finally, a numerical example is used to demonstrate the advantages of the proposed approaches.

GAIN-SCHEDULING IN THE l1 FRAMEWORK: A FLIGHT CONTROL EXAMPLE

This paper describes the synthesis of l1-optimal gain-scheduled outputfeedback controllers for linear parameter-varying plants. It is shown how a recently developed synthesis method can be applied to a standard example from flight control. In particular, different ways for obtaining discrete-time models of the continuous-time plant with low-dimensional parameter-dependence are described. Moreover, some insight is given into weight and performance specifications in l1 control. Simulation results of the sampled-data closed-loop system confirm the applicability and performance of the proposed control method.

Gain Scheduled Output Feedback Control Based on LTI Controller Interpolation that Preserves LPV H Performance

A new approach to the design of a gain scheduled output feedback controller based on linear time-invariant (LTI) controller interpolation that preserves H∞ performance without a varying-parameter rate feedback is proposed. After the controller design is translated into parameterized linear matrix inequalities about parameter matrices based on a parameter-dependent Lyapunov function, the sufficient condition is given for the partition of the varying-parameter set based on the concept of “H∞ performance covering”. The varying-parameter set is thus partitioned into sufficiently small subsets. After the constant matrices are found for each of the subsets, the required continuous parameter matrices are obtained by using interpolation. The proposed controller overcomes the drawback that the gain scheduled controller may not be found by using the existing gain scheduled linear parameter varying (LPV) controller synthesis. Moreover, the varying-parameter rate feedback is eliminated and the conservatism of the controller design is reduced by means of limiting the upper bound of the varying-parameter rate. Simulation and experiment results prove the effectiveness of the proposed controller.

Robust Finite-Time Stabilization via Dynamic Output Feedback: An LMI Approach

In this paper we consider the finite-time stabilization problem for a linear system subject to parametric time-varying uncertainties. The main result of this work is a sufficient condition for the design of a dynamic gain scheduled output feedback controller which renders the closed loop system finite-time stable for all possible time realizations of the parameters. Such sufficient condition is given in terms of an LMI optimization problem; this gives the opportunity of fitting the finite-time control problem in the general framework of the LMI approach to the multiobjective synthesis. In this context an example illustrates the design of a controller which guarantees, at the same time, finite-time specifications and some pole placement requirements.

Robust finite-time stabilization of linear uncertain systems via gain-scheduled output feedback

Abstract In this paper we consider the finite-time stability problem for linear systems subject to time-varying parametric uncertainties. First we provide a sufficient condition for robust finite-time stabilization via state feedback in terms of a Linear Matrix Inequalities (LMI's) feasibility problem; such condition is shown to be less conservative than those proposed in the previous literature. Then we consider the output feedback case; sufficient condition for robust finite-time stabilization are given for different kinds of controllers: static, dynamic, dynamic and gain-scheduled with the parameters. Although the output feedback problem cannot be reduced to an LMI's based feasibility problem, we provide an iterative algorithm which has proved to be efficient in most cases. A detailed example illustrates the effectiveness of the proposed technique.

L2 Bibo Output Feedback Stabilization With Saturated Control

For the problem of stabilization of mildly nonlinear systems with saturated control, a simple and computationally attractive method of designing a stabilizing gain scheduled output feedback is proposed. The resulting controller is supplied with rigorously proven input/output performance bounds. For the case of stabilization of a linear time invariant system without exponentially unstable modes, the closed-loop map from the plant disturbances and state estimation noise to the state and control variables is shown to be L2-bounded. For an exponentially unstable open-loop plant, the asymptotic stability is guaranteed in the case of disturbances which do not affect the exponentially unstable states of the system directly. In particular, for the reference tracking problems with actuator rate saturation, stability with respect to the reference input takes place.

Design and robustness analysis of gain-scheduled control system for parabolic flight

The problem of designing a flight control system for the tracking of parabolic trajectories to guarantee microgravity conditions within the aircraft cabin is considered. The proposed control action consists of two parts. The first one is a feedforward control guaranteeing good tracking of the desired parabola in the absence of environmental disturbances. The second part is a gain-scheduled output feedback to counteract possible misalignments between the desired output trajectory and the actual one. An estimation of the maximum output displacement in the presence of uncertainties and disturbances (wind gusts) is carried out. Simulation results are provided for a remotely piloted vehicle.