Analysis of the Effects of Truncation on the EWMA Observer

Author

Braun, Martin W. ; Patel, Nital S.

Author_Institution

Intel Corp., Chandler

fYear

2007

fDate

22-25 Sept. 2007

Firstpage

472

Lastpage

477

Abstract

For many years the exponentially weighted moving average (EWMA) observer has been used in practice for advanced process control (APC) in the semiconductor industry. A common practice is to truncate the length of data used in creating an EWMA estimate of the system state. This practice enables easier maintenance of the installed controller, while running the risk of tighter robust stability margins. This paper provides a measure of when it may be safe to assume the stability results of a truncated EWMA are well predicted by those expressions for an infinite EWMA formulation. Additional stability criteria are provided for situations otherwise. A method for extending auto-tuning methods for use with truncated EWMA filters is also presented.

Keywords

moving average processes; observers; process control; robust control; semiconductor device manufacture; advanced process control; auto-tuning methods; exponentially weighted moving average observer; robust stability; semiconductor industry; system state estimation; truncation effect; Automation; Electronics industry; Finite impulse response filter; IIR filters; Observers; Process control; Robust stability; Signal processing; State estimation; USA Councils;

fLanguage

English

Publisher

ieee

Conference_Titel

Automation Science and Engineering, 2007. CASE 2007. IEEE International Conference on

Conference_Location

Scottsdale, AZ

Print_ISBN

978-1-4244-1154-2

Electronic_ISBN

978-1-4244-1154-2

Type

conf

DOI

10.1109/COASE.2007.4341677

Filename

4341677