Relay test for anisochonic models - time domain solution

Abstract

Anisochronic models are characteristic for containing state delays. These models have some practical and attractive features; e.g. they enable to fit the dynamics of systems with very high order. This contribution utilizes an idea of anisochronic models identification based on limit cycle information obtained from relay feedback test is investigated. Unlike conventional approaches connected with the frequency analysis of a plant transfer function, the proposed alternative methodology is based on computation with functional differential equation only, i.e. in time domain. Plant parameters to be identified are obtained analytically. In addition, parameter estimation is also improved using autotune variable (ATV+) technique which required an additional delay element. An illustrative example where parameters of a tenth order system are approximated by a first order anisochronic model is presented.