The objective of this study is to propose an observer design for nonlinear systems by using an augmented linear system derived by application of a formal linearization method. A given nonlinear differential equation is linearized by the formal linearization method which is based on Taylor expansion considering up to the higher order terms, and a measurement equation is transformed into an augme...

In this paper, a disturbance observer based controller is proposed for the compensation of nonlinear friction in a servodrive system. The designed nonlinear controller uses the estimated system states (position, velocity) and disturbance to enhance tracking performance of the servodrive using high stiff gains for the compensation of the effects of nonlinear friction. The effectiveness of this d...

pH control is a challenging problem due to its highly nonlinear nature. In this paper the performances of two different adaptive global linearizing controllers (GLC) are compared. Least squares technique has been used for identifying the titration curve. The first controller is a standard GLC based on material balances of each species. For implementation of this controller a nonlinear state...

This work studies the problem of design of discrete-time nonlinear observers in the presence of exogenous disturbances. In particular, the present work proposes a systematic design method for discrete-time nonlinear state and disturbance observers in modular form, consisting of an observer for the disturbance-free part of the system, along with a disturbance observer and a stateestimate correct...

This paper deals with the design of a nonlinear observer for the inverted pendulum. The observer uses the standard structure of the linear observer with the linear model replaced by a nonlinear model. Nominal observer gains are determined from a linearized model. This model is also used to find a compromise between robustness and performance. The stability of the observer is then discussed and ...

This paper is concerned with stability analysis problem of nonlinear observer design for a class of multilink flexible manipulators (MLFMs). Specifically, the dynamics of the MLFM is modeled by the use of a Lagrangian approach. In a unified algebraic Riccati matrix equality (ARME) framework, one corresponding error-state system is proven to be asymptotic stable in the mean square (ASMS) for a n...

The problem of estimating unmeasured state and disturbance variables for nonlinear process control applications is considered. We assume that the process model is affine with respect to the unmeasured disturbances and any unmeasured state variables. The disturbances are considered as additional state variables, and a nonlinear observer is designed for the augmented state-space system. The obser...