Design and experiments for model-free PI control of DC drives

This paper proposes the model-free PI control design for direct current (DC) drives. A model-free PI control system structure is considered in the framework of reference tracking control using a first-order nonlinear dynamic system as a local approximation of the process model. The derivatives are estimated numerically using a Savitzky-Golay filter that solves the differentiation and also the smoothing. The model-free PI control system structure is applied to the speed control of a laboratory nonlinear DC drive as a representative mechatronics application. The experimental results for three different reference input shapes show the very good performance in model reference tracking, reference trajectory tracking and numerical differentiation.