Vibration suppression of rotating arm in LED chip sorter using feedforward-feedback control with an optimal curve

Abstract The flexible vibration of a rotating arm and the control strategy are the two major sources of vibration of a rotating arm in an LED chip sorter. In this paper, the dynamic characteristics and servo control of a rotating arm are studied in order to suppress vibration. Three servo motor driving curves are designed and the modal characteristics of rotation are analyzed theoretically. The geometric stiffening phenomenon is observed, and an optimal curve is selected in theory. The servo control system adopts a feedforward-feedback control and a filter is used in the speed loop to attenuate the resonance oscillation introduced by the input signal. Then, an experimental table for the rotating arm is designed and built to study the method of vibration suppression. The experimental results show that the selected curve and the control strategy proposed can effectively suppress the vibration of the end of the rotating arm. The same methods are also applied to the LED chip sorter with the experimental results indicating that the positioning errors of LED chips are reduced.