The main objective of applying robust active control to base-isolated structures is to protect them in the event of an earthquake. Taking advantage of discontinuous control theory, a static discontinuous active control is developed using as a feedback only the measure of the velocity at the base. Moreover, due to that in many engineering applications, accelerometers are the only devices that pr...

It is a pleasure to help honor my friends and former colleagues Dale Henderson, Dick Porter, and Peter Tinsley, by discussing Williams' fine paper and the important ongoing research program to which it contributes, all of which is very much in the Henderson-Porter-Tinsley tradition of path-breaking application of optimal control methods to the conduct of monetary policy. The recent robust contr...

In this paper we will show that contouring performance can be viewed as a regulation problem in a curvilinear task coordinate frame that is attached to the desired contour. By transforming the machine tool feed drive dynamics to this task coordinate frame, an adaptive robust control (ARC) law is derived to improve the contouring performance under system parameter variation and bounded disturban...

This paper solves the stabilization problem for positive linear discrete-time systems subject to time-delays, under state and control constraints. The synthesis of state-feedback stabilizing controllers is solved in terms of Linear Programming. The proposed approach deals with the stabilization with bounded controls and states, in the presence of possibly unknown delays. Also, the robust contro...

A second order sliding mode control algorithm is presented for robust control of the liquid level in a pair of interconnected tanks. The controller is implemented on a laboratory rig. The implementation results show robustness to parameter variations such as tank area, the admittance coefficients of various pipes, leakage in the tanks and uncertainty in the pump dynamics. The potential of secon...

An application is presented of1 synthesis to the robust control of a large  exible space structure experimental testbed called Daisy. A perturbed left-coprime factorization of Daisy’s dynamics is used to capture the uncertainty in the modes. Designs of the 1 synthesis controller based on left-coprime factorizations of 46th-order collocated and noncollocatedmodels of Daisy are presented togethe...

We develop control laws for the pendular motion of a spinning tethered satellite system. The control laws are developed using a simplified system model that contains unknown disturbance terms that account for unmodeled dynamics in the simplified model. Principles of sliding mode and adaptive nonlinear control design are used to develop control laws that drive the pendular motion to a desired re...

Observer design is classically considered as a dual problem to state feedback. But very few results address this issue in the context of uncertain system, at least in comparison of robust state-feedback design. This fact has motivated us for studying robust design of both state-feedback gains and Luemberger-like observers and we in particular show that in case of uncertain systems these two des...

Moat realistic control problems involve both some type of time-domain constraints and model uncertainty. However, there presently exist few design methods capable of simultaneously addressing both issues. We recently proposed to address this class of problem by using a "constrained robustness measure", generated by a constraint-set induced operator norm, to assess the stability ptoperties of a ...