摘要:

AbstractThe stability of adaptive ARMA predictors, which present random time‐varying poles, is investigated. The updating algorithm is a suboptimal version of the stochastic gradient. For narrow‐band inputs local and quasi‐periodic instabilities occur. At those times the output error increases exponentially but has essentially the frequency of the unstable pole of the MA predictor part. This unstable error generates in the algorithm a stabilizing drift for the (unstable) MA parameters. This behaviour, called self‐stabilization (SS), is attenuated by inclusion of a (leakage) σ‐factor in the updating algorithm.The SS analysis is applied to the important application of the ADPCM encoding of speech signals. It is shown that in successive encoder/decoder connections the SS phenomenon results in the accumulation of quantization distortions at each transcoder. For a digital transmission chain this is a seriou

ISSN:0890-6327    

DOI:10.1002/acs.4480020102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe problem of designing a robustly stable pole placement indirect adaptive controller in the presence of output disturbances and unmodelled dynamics is addressed. The key features of such a design are the following. (1) The unknown parameters are estimated by a normalized least‐squares algorithm with a dead zone to provide the stability robustness with respect to bounded disturbances and ‘small’ unmodelled dynamics. (2) The estimated model controllability is ensured by modifying the control law over a finite time. The modification involved consists of adding an internal impulse excitation and ‘freezing’ the controller p

ISSN:0890-6327    

DOI:10.1002/acs.4480020103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractWe consider systems in which the plant parameters and non‐linearities can vary unpredictably within known bounds. Their variations can be arbitrarily fast, even discontinuous. The desired plant output is defined as the output response to a governing input of an appropriately selected reference model. For this class of problems the concept of stable and exponentially stable tracking is defined. The problem studied is the synthesis of an adaptive controller having adjustable parameters to guarantee (stable, exponentially stable) tracking for the plant subject to the action of external disturbances. A solution to the problem is established for a class of plants determined by a special structure. Simulation results illustrate excellent tracking behaviour for a second‐order plant with unknown parameters and non‐linearities having unpredictable varia

ISSN:0890-6327    

DOI:10.1002/acs.4480020104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0890-6327    

DOI:10.1002/acs.4480020105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0890-6327    

DOI:10.1002/acs.4480020106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0890-6327    

DOI:10.1002/acs.4480020107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0890-6327    

DOI:10.1002/acs.4480020108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0890-6327    

DOI:10.1002/acs.4480020109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0890-6327    

DOI:10.1002/acs.4480020110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0890-6327    

DOI:10.1002/acs.4480020101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY