Neeli Satyanarayana

Sliding mode control of uncertain systems using multirate output feedback functional observer

This paper considers the problem of designing a sliding mode control for a linear time-invariant system subject to uncertainties. The proposed technique uses the concept of functional observer and multirate sampling for computing the required control. The necessary conditions for the existence of a controller is given. The proposed controller requires less number of output samples than any other method based on multirate output sampling. A numerical example is considered to demonstrate the procedure and efficacy of the approach.

Multirate output sampling linear functional observer-based state feedback for systems with delay in state variables

In this paper the design of functional observer-based state feedback controller for linear time-invariant (LTI) systems with time-delay in state variables is addressed. To illustrate the approach we consider a dual-rate system with fast output measurements and slow control actions. Necessary and sufficient conditions are given for existence of proposed controller with minimal number of output samples than those already employed multirate output sampling (MROS) and full state observability is not a necessary condition. By the so-called lifting method, time-delay systems are transformed into delay-free systems such that simple conditions have been developed for the stability and stabilisation. Design example is given to illustrate the procedure for the design of proposed controller and to demonstrate the advantages.

Design of multirate output sampling based linear functional observer and state feedback

This paper addresses the problem of realizing a predefined linear function of a state using multirate sampling for the purpose of implementing state feedback control law. For that, the functional should be expressed as a linear combination of output vector constructed by sampling system output at faster rate. This method can also be applied for systems having unobservable modes. The proposed method has the advantage that the number of output samples required can be less than the observability index. Numerical example is considered to illustrate the procedure of proposed method.

Multirate Functional Observer Based Discrete-Time Sliding Mode Control

In this chapter, a brief introduction to the functional observer, multirate output sampling and discrete-time sliding mode control will be given. Using the concept of multirate sampling of plant output, a functional observer based sliding model controller has been designed for systems with uncertainty. The necessary and sufficient conditions are given for the design of the proposed controller using the minimal number of output samples. A numerical example is considered to demonstrate the procedure and efficacy of the approach.

Minimum variance functional filtering for multirate sampled systems

In this paper, we propose a new method of minimum-variance functional filtering for a class of sampled-data systems. The proposed method is based on multirate sampling of the plant output. This work includes the formulation of multirate output model for continuous-time system having noise in plant dynamics and measurement and necessary and sufficient conditions are given for existence of functional with minimal number of output samples. Numerical example is given to illustrate the procedure and its merits.

Multirate output functional filter design and control

The Kalman filter is a recursive estimator for a linear dynamic system with uncorrelated white process and measurement noises. In this paper, we consider the problem of unbiased minimum-variance functional estimation for linear discrete-time stochastic systems. The proposed method is based on multirate sampling of plant output. The necessary and sufficient conditions for the existence of the functional filter are given and the stability of the filter is discussed. A numerical example is considered to demonstrate the procedure and efficacy of the approach.

Design of functional observer based controller for uncertain systems

A completely new method of functional observer design based on multirate output sampling for time-invariant linear uncertain systems has been proposed. If certain conditions are satisfied, the proposed method will estimate required functional with less number of output samples than those of the previous work. Analysis are presented, if proposed functional observer is used to stabilize the plant by feedback the system. The proposed method is more practical and easy to implement as linear state feedback based controller is realized using output samples. Numerical example is considered to show the design procedure and its merits.

Multirate output functional observer in linear feedback for systems with unknown inputs

This paper proposes a new method to design a scalar dynamical functional observer based feedback control, for a class of linear sampled-data systems with additive disturbances. The control action consists of the function of system state and disturbance components. The design of the function of state is based on the pole-placement technique and the function of disturbance is for the complete disturbance-counteraction on system performance. This work is based on the combination of functional observer design and multirate output sampling technique. Necessary and sufficient conditions for existence of the proposed controller are derived and the design procedure is given. It is shown that the proposed method relaxes some of the conditions of disturbance decoupled functional observer design, provided that the variation of disturbance in the two consecutive sampling instances is not significant. Numerical example is considered to illustrate the design procedure and its simplicity.

State Based Functional Observer Design for Linear Uncertain Systems Using Multirate Output Sampling

In this paper a design of controller has been proposed for linear uncertain systems based on multirate output sampling for the purpose of state feedback and nullification of disturbance effect on system response. If certain conditions are satisfied, construction of proposed functional type controller require less number of output samples than any other method based on fast output sampling. The advantage of proposed method is that it can be extended to unobservable systems and avoids the boundedness constraint on disturbance. A numerical exam- ple demonstrates the procedure, superiority in terms number of required output samplings and application to unobservable systems.