Gain scheduling control for electro-hydraulic servo system considering time-delay modeling error

Electro-hydraulic servo system has been used in many industrial applications for high power in size, high response and fine repeatability. But, load variation causes a degradation of control characteristic. We introduce a scheduling parameter which is a function of hydraulic force against load, and apply it for gain scheduled controller design to maintain steady control performance under comparatively large load variation. Furthermore, we take time-delay into consideration as modeling error so that achieve desirable follow-up performance. Usefulness of this approach is confirmed by experiments.