Design and Analysis of Disturbance Force Observer for Machine Tools Application

In milling process, the quality of tracking performance is influenced by the characteristics of the cutting forces generated during the material removal process. The undesired frequency harmonics of the cutting force contributes negatively to the positioning accuracy. An effective compensation of these harmonics is desired. This paper presents and discusses a disturbance force observer as an approach to estimate and compensate effect of external disturbance forces on system performance. Knowledge of the properties of the disturbance signal is essential for the design of an observer. A Fast Fourier Transform analysis of the disturbance force reveals the harmonics content of the signal. The frequency harmonics is a function of the spindle rotational speeds. The results show effective compensation of the cutting force with reduced amplitudes of the harmonics frequency content.