Papers by Keyword: Sinusoidal Excitation

Abstract: For nano-positioning systems with piezoelectric actuators used for dynamic grinding control, sinusoidal command signals will used and will give additional problems compared with the commonly used step signals because of the hysteresis effects, which require a good modeling approach. The proposed approach of multiple polynomial regression with first order continuity gives a relative modeling error of 2.65%. The method reduces the error by 26.3-80.2% in comparison with the methods using the single, dual, and multiple polynomial regression with zero order continuity.

Abstract: The controllability of a magnetorheological(MR) fluid squeeze film damper under a sinusoidal magnetic field was experimentally studied on a flexible rotor. It is shown that the frequency of the excitation magnetic field has a great effect on the controllability of the MR fluid damper. As the magnetic field frequency increases, the controllability of the MR fluid damper significantly reduces. There is a maximum frequency of the magnetic field for a given magnetic field strength or a minimum strength of the magnetic field for a given magnetic field frequency to make the dynamic behavior of the MR damper be controllable. When the magnetic field frequency is over the maximum one or the magnetic field strength is less than the minimum one, the controllability of the MR fluid damper almost completely disappears and the dynamic behavior of the MR fluid damper with the sinusoidal magnetic field is the same as that without the magnetic field.

Abstract: For micro-positioning systems using piezoelectric actuators for precision grinding process control, sinusoidal command signals will be used and will give additional problems in comparison with the commonly used step signals due to the hysteresis effects, which require a good modeling approach. In order to avoid the discontinuity problem in obtaining the values of the piezoelectric constant, a new approach of direct mapping with polynomial fit is proposed. Theoretical and experimental studies are conducted and comparative studies are made. Compared with the single polynomial approach, the proposed method of direct mapping with polynomial fit is able to reduce the modeling error to 12.5%, which is 6.5% lower, and the problems in obtaining the values of the piezoelectric constant are avoided. The proposed approach is shown advantageous. Further studies are necessary to significantly reduce the modeling error.