Spatial observer-based repetitive controller: An active disturbance rejection approach

Linear Repetitive Control has proven to be an effective strategy to compensate for periodic disturbances in mechatronic systems that operate at constant speed; however, it renders very poor performance in varying speed applications. In this work, a Repetitive Controller based on a Generalized Proportional Integral (GPI) observer under Active Disturbance Rejection approach is presented and formulated in spatial domain. The inclusion of the linear GPI observer makes possible to see the spatial non-linear system as a simplified linear one by means of an on-line estimated unified disturbance term. Experimental results show that the presented linear approach successfully rejects periodic disturbances under varying speed conditions.