Designing and tuning robust feedforward controllers

A model-based design and tuning procedure is proposed for feedforward controllers, which accounts for model uncertainties in SISO systems. Proper relationships for the analysis of feedforward–feedback control systems show that tuning the feedforward controller is not completely independent from the feedback-loop spectral characteristics. Similarly, fine tune of the associated feedback controller requires to be based on the residual disturbance remaining after the feedforward control action. Consequently, the simultaneous tuning is proposed for efficiently solving disturbance-rejection problems. Two application examples show that the robust combined tuning gives satisfactory results for different dynamics and different tuning requirements.