Dynamics of parameter tracking

The paper discusses the use of a modulus error parameter tracker for estimating two unknown parameters in a simple dynamic system. The tracker dynamics are analysed in detail and the tracker is shown to be stable, but not asymptotically stable, and the existence of a circular terminal orbit is demonstrated. It is destabilised by amplifier offset, but this implementation error may be reduced by application of a high frequency perturbation. The response to certain useful test inputs is determined, and by use of involute geometry the effects of time-varying plant parameters analysed. A brief account of the tracking of lung resistance and lung elastance of artificially ventilated subjects is given.