Research ArticleGeneralized proportional integral control for periodic signals under active disturbance rejection approach

- This work proposes a GPI control scheme for rejection/tracking of periodic signals.
- Repetitive control and GPI control provide comparable performance at nominal speed.
- GPI control shows good results against periodic disturbances of varying frequency.
- GPI observer-based control keeps a simple structure without adaptive mechanisms.

Conventional repetitive control has proven to be an effective strategy to reject/track periodic signals with constant frequency; however, it shows poor performance in varying frequency applications. This paper proposes an active disturbance rejection methodology applied to a large class of uncertain flat systems for the tracking and rejection of periodic signals, in which the possibilities of the generalized proportional integral (GPI) observer-based control to address repetitive control problems are studied. In the proposed scheme, model uncertainties and external disturbances are lumped together in a general additive disturbance input that is estimated and rejected on-line. An illustrative case study of mechatronic nature is considered. Experimental results show that the proposed GPI observer-based control successfully rejects periodic disturbances even under varying speed conditions.