Shinji Mitsuta

Vibration Reduction of Transfer Feeder by Active Vibration Control.

Recently, transfer feeders, which are conveyance equipment for large-size press machines, have become larger in size and faster in speed for the elevation of productivity. For this reason, the stiffness of the structure has decreased, causing various vibration problems. To solve this problem, we proposed a method where the dynamic damper is located on the vibration transmission path from the objective vibration system to the vibration source. But the effect is not always sufficient to make the machine more accurate. Therefore we developed the active vibration control system, using the actuator located on the motion transmission path. The validity of this method is shown in the simulation and the result of the application to transfer feeder.

Vibration and Motion Control of Flexible Structures by Hybrid Dynamic Absorber.

Recently, the necessity of lighting and high-speed for the machines is increasing. This paper concerns the vibration and motion control by the the control system which combined a servo controller with a hybrid dynamic absorber. In our method, the vibration control and the servo control are designed independently. Firstly, the dynamics of the tower structure and the servo motor are modeled. It is shown experimentally that although vibration control by the servo controller alone causes the instability due to nonlinear elements such as the friction or the rattle, the hybrid dynamic absorber is hard to cause this sort of the instability. On the comparison of the vibration control effect and the control force, the hybrid dynamic absorber needs the less force. Finally, to know its effect we evaluated the motion (triangle wave, sine wave) of the flexible structure. Effectiveness of this vibration and motion control method to the flexible structure is demonstrated by simulation and experiment.

Vibration Control of Moving Flexible Structure by LMS Adaptive Control

In this study, we considered that vibration is actively reduced by arranging an actuator on the motion transmission path from the drive system to the flexible structure. Generally, we often reduce the vibration of a flexible structure by feedback control, by which it is possible to obtain good effects for reducing the residual vibration. But the vibration of a moving flexible structure is forced vibration which is caused by motion acceleration, so it is not possible to reduce the vibration effectively by means of the state feedback control using the LQ control theory. Thus, for vibration during motion, we use the adaptive control with the LMS (least-mean-square) algorithm. With the proposed method, the forced vibration component for the disturbance can be reduced effectively, making use of the fact that the disturbance of the vibration system is motion acceleration. Therefore, LMS adaptive control is made use of during flexible structure motion, and feedback control is made use of after interruption. We proposed a method that reduces not only the vibration peak during motion but also the residual vibration after interruption effectively, changing these two control methods according to the motion of the flexible structure. Furthermore, in this study, the validity of this method is examined by simulation and experiment.