Bumpless Transfer Filter for Exogenous Feedforward Signals

This brief presents a bumpless transfer filter to attenuate signal magnitude bumps at transitions between exogenous feedforward (FF) signals in a feedback/FF control architecture. Importantly, this filter does not modify the carefully constructed exogenous FF signal at time indices away from a signal transition. Filter architecture, stability criteria, and performance considerations are detailed. An example application demonstrates filter efficacy with a piecewise iterative learning control scheme applied to a serial positioning robot. The bumpless transfer filter attenuates exogenous signal magnitude bumps at transitions between signal segments; a smoothed exogenous signal yields improved performance at transition locations and thereby decreases the 2-norm of the error signal by 12% on average.