In this paper we use Hamilton-Jacobi-Bellrnan theory to derive optimal nonlinear feedback control laws for a special class of nonlinear systems. The results are applied to a spacecraft angular velocity stabilization problem with two torque inputs. A family of optimal nonlinear feedback controllers that globally asymptotically stabilize angular velocity is established. Special cases of this fami...

Many of the physical phenomena, like friction, backlash, drag, and etc., which appear in mechanical systems are inherently nonlinear and have destructive effects on the control systems behavior. Generally, they are modeled by hard nonlinearities. In this paper, two different methods are proposed to cope with the effects of hard nonlinearities which exist in friction various models. Simple inver...

We present an approach for constructing optimal feedback control laws for optimal regulation of a rotating rigid spacecraft. We employ the inverse optimal control approach which circumvents the task of solving a Hamilton-Jacobi equation and results in a controller optimal with respect to a meaningful cost functional. The design reported in the paper is the rst optimal control design for attitud...

Implementation of effective control schemes for Nonlinear Systems is currently being studied comprehensively. In this paper, robust control schemes for trajectory tracking of Nonlinear Permanent Magnet Stepper Motor system has been proposed. Direct Quadrature (DQ) transformation technique has been employed to convert the system dynamics to DQ frame. Initially, a conventional PID controller alon...

In this paper, an observer based fuzzy adaptive controller (FAC) is designed fora class of large scale systems with non-canonical non-affine nonlinear subsystems. It isassumed that functions of the subsystems and the interactions among subsystems areunknown. By constructing a new class of state observer for each follower, the proposedconsensus control method solves the problem of unmeasured sta...

This thesis uses the idea of lifting (or embedding) a nonlinear controlled dynamical system into an infinite-dimensional space of measures where this system is equivalently described by a linear equation. This equation and problems involving it are subsequently approximated using well-known moment-sum-of-squares hierarchies. First, we address the problems of region of attraction, reachable set ...

A conical tank in which the diameter changes with the tank height, allows the use of feedback control used in complex nonlinear systems, such as adaptive control. This project modified an existing system of two interacting tanks by inserting a removable solid cone into one of the tanks. This modification created two new nonlinear configurations, one of which had a discontinuity. Optimal control...

Switched controller design for nonlinear continuous and discrete-time systems under an arbitrary switching signal using the gain scheduling approach is addressed in this paper. The obtained controller design procedures for continuous and discrete-time systems are in the bilinear matrix inequality form. The proposed design procedure ensures multi parameterdependent quadratic stability of the swi...