Kirthi Walgama

Inherent observer property in a class of anti-windup compensators

Owing to the types of non-linearities involved, the analysis and the comparison of different anti-windup compensators that are available in the literature become difficult. Towards achieving a better understanding of the mechanisms of these anti-windup compensators, we here expose the observer property inherent in a class of anti-windup compensators. This observer property allows us to unify these anti-windup compensators as special cases of the generalized anti-windup compensator due to Astrom and Wittenmark (1984), and provides a general framework to investigate their performance.

Repetitive Control Theory and Applications - A Survey

Abstract The aim of this paper is to present repetitive control, controllers for rejecting periodic disturbances or tracking periodic reference signals, This survey covers both continuous and discrete time theory, together with a number of applications

Speed controller strategies for distributed motion control via Ethernet

Investigations on adapting Ethernet for distributed control systems is an interesting topic in the motion control industry, due to its commercially off the shelf hardware availability and compatibility at a comparatively lower price. Conversely, the communication through shared media in standard Ethernet is non-deterministic resulting in stochastic delays of data transfer. This paper experiments the solutions, through a control engineering perspective, for the time delay problem encountered in distributing the speed control loop of a Brushless DC motor via an Ethernet network. The mean of the control delay (T) is used in standard controller strategies modified for time delayed systems.

On the convergence properties of adaptive pole-placement controllers with antiwindup compensators

To avoid the windup problem in adaptive pole-placement controllers in the presence of a saturating input, an antiwindup compensator based on a generalization to the conditioning technique is introduced to the controller. This modification to the controller also provides a unified approach to investigate the asymptotic properties of the adaptive controllers with a class of antiwindup compensators, at least, when applied to stable processes. >

A feedforward controller design for periodic signals in non-minimum phase processes

A novel feedforward controller is derived in this paper for asymptotic decoupling of measurable conf disturbances and asymptotic tracking of conf setpoints, when the process is non-minimum phase. The resulting controller, which provides necessary amplitude phase precompensation, is a finite impulse response (FIR) filter and hence the problem of non-minimum phase zero cancellation is avoided. The controller can be designed by solving a diophantine identity, in which the parametric model of the process and the model of the conf signal are involved. However, in the presence of process model uncertainties, the controller can instead be designed by using only the frequency response of the process at the frequencies defined by the conf signals. The proposed controller can be useful in a two-degree of freedom controller design, to avoid the introduction of the internal model of the conf signal in the feedback loop which may give rise to stability robustness problems.

Sensorless adaptive control of permanent-magnet synchronous motors based on a voltage error vector

There has been significant development in and attention to sensorless control (i.e. measurement is replaced by estimation) of permanent magnet synchronous machines (PMSM) of various types. We present some intermediate results obtained with a position (and speed) estimation method based on a voltage error vector for PMSMs. The results mainly focus on the cancellation of periodic disturbances that appear in the real system, which causes instabilities in the estimation algorithm.

Dempster–Shafer Information Filtering Framework: Temporal and Spatio-Temporal Evidence Filtering

This paper presents an information processing framework for distributed sensor networks. The framework is capable of directly processing temporally and spatially distributed multimodality sensor data to extract information buried in the noise clutter. Moreover, we introduce distributed algorithms to implement spatio-temporal filtering applications in grid sensor networks within the context of the framework. The proposed framework is based on the belief notions in Dempster-Shafer (DS) evidence theory and evidence filtering method. Further analysis is done by exploiting a fire propagation scenario when high noise is present in the sensed data. We compare intuitively appealing results against DS fusion method to grant further credence to the proposed framework.