Takashi Kitahara

Active microvibration control of precision manufacturing factories with smart structure using piezoelectric actuators

In order to achieve more perfect vibration-free environment in precision manufacturing facilities such as semiconductor manufacturing factories, and apply steel frame structures to semiconductor manufacturing factories of the next generation, a smart structure was tested for active microvibration control of a 2-story steel frame building model of a 5 X 3 X 4H m outer size and a 2,500 kg total weight which was excited by ambient ground vibration. In the structure, piezoelectric actuators attached to the columns and the beams were used for the microvibration control by bending moment control of them. The controller was designed using the H-infinity control theory. The tests showed that the smart structure could effectively reduce the 3D microvibration of the building model, and its applicability to floors and even entire buildings of semiconductor manufacturing factories having steel frame structures.

Calculation Approach of Optimum Cutting Surfaces of Extra Length of Pipe Spools

To connect a pipe spool between existing pipes with high accuracy for power plant constructions, a calculation approach which figures out appropriate cutting positions and angles of extra length areas of the spool has been developed. In this approach, center positions and axes of end surfaces are modeled numerically based on three-dimensional measurement of each pipe, and the appropriate cutting surfaces are calculated by geometric analysis of the models with considering for ease of cutting work at the construction site.This paper described a modeling method of pipes, a calculation algorithm of the proper cutting surfaces of the spool, and a verification result of the calculation.Copyright

Comprehensive Active Microvibration Control Systems Using Piezoelectric Actuators for Base-Isolated Precision Manufacturing Facilities

Active microvibration control is expected to be applied to floors and even entire buildings of precision manufacturing facilities to meet requirements for more perfect vibration-free environment in the facilities. It is desirable that such facilities are effectively protected from earthquake attacks by using seismic isolation. For base-isolated precision manufacturing facilities, comprehensive active microvibration control systems were studied to control both of microvibrations born in the inside due to equipment and human walks and microvibrations coming from the outside due to ground vibrations and winds. A base-isolated 2-story building model of a 3m×5m×4mH external size and a 6.9t total mass was used for experiments, in which 4 multistage rubber bearings and a viscous shear damper were installed for the seismic isolation, while 20 piezoelectric actuators were attached to the columns and the beams and 8 piezoelectric actuator units were installed in the seismic isolation layer for the active control. The tests showed that the system consisting of the passive base-isolation system and the piezoelectric actuators attached to the columns and the beams could most effectively control the three-dimensional microvibrations due to the external and the internal disturbances.