The computation of optimal H∞ controllers with a prescribed order is important for their real-time implementation. This problem is well-known to be non-convex, and only algorithms that compute upper bounds on the global optimal value are known. We present a method to compute lower bounds by re-formulating the problem as a robust analysis problem, where the controller variables are the “uncertai...

The development of an innovative controller for looper and tension control in hot strip finishing mills is traced based on the combination of H∞ and ISMC (integral sliding mode control) approaches. First, an H∞ controller is designed to robustly attenuate the unmatched disturbances in the angle and tension loops. Then, ISMC is used to overcome the matched disturbances in the actuators which gua...

The design of a robust nonlinear H∞ static output feedback controller for parameter dependent polynomial systems is a hard problem. This paper presents a computational relaxation in form of an iterative design approach. The proposed controller guarantees the L2-gain of the mapping from exogenous input noise to the controlled output is less than or equal to a prescribed value. The sufficient con...

We study the H control problem for an a$ne singularly perturbed system, which is nonlinear in the state variables. Under suitable assumptions on the linearized problem, we construct -independent composite and linear controllers that solve the local H control problem for the full-order system for all small enough . These controllers solve also the corresponding problem for the descriptor system....

This paper presents the H∞ control of a pressure swing adsorption process. This separation process is characterized by periodic operations. The objective of the control is to assign the trajectory of the output system purity and to reject the perturbation on the inlet composition. The control design is synthetized from some Hammerstein model that approximates the cyclic process. The control sch...

A new method for robust fixed-order H∞ controller design for uncertain time-delayed MIMO systems is presented. It is shown that the H∞ robust performance condition can be represented by a set of convex constraints with respect to the parameters of a linearly parameterized primary controller in the Smith predictor structure. Therefore, the parameters of the primary controller can be obtained by ...

Abstract: In this paper a state feedback controller is designed to stabilize a discrete-time nonlinear and uncertain system. The Takagi Sugeno (TS) fuzzy model with norm-bounded uncertainties is considered for modelling the nonlinear system. Beyond stability, a mixed (LQ/H∝) index is also considered, which simultaneously guarantees an upper bound of LQ cost and is robust for unknown external di...

In this paper, the problem of designing fixed-order robustH∞ controllers is considered for linear systems affected by polytopic uncertainty. A polynomial method is employed to design a fixed-order controller that guarantees that all the closed-loop poles reside within a given region of the complex plane. In order to utilise the freedom of the controller design, an H∞ performance specification i...

In order to control a single quadcopter with a cable-suspended payload to follow the desired trajectory, a mixed H2/H∞ controller with constraints is developed. Firstly, the EulerLagrange dynamic model is built and linearized. Then the extended model for path tracking problem is designed. Based on linear matrix inequality (LMI), state feedback controller H2 and H∞ with constraints is illustrate...

This paper proposes a new technique to design a fixed-structure robust loop shaping controller for the pneumatic servosystem. In this paper, a new method based on a particle swarm optimization (PSO) algorithm for tuning the weighting function parameters to design an H∞ controller is presented. The PSO algorithm is used to minimize the infinity norm of the transfer function of the nominal closed...