Research on Base-acceleration-integral Feedback Skyhook Control Algorithm for Active Isolation System of Equipment

The high-tech factory buildings in Taiwan often adopts seismic resistant design due to micro-vibration requirements. Although the safety of the building structure is guaranteed by proper seismic resistant design, the equipment inside the structure might still have a large base excitation induced by floor acceleration. Therefore, the seismic isolation system that can protect the internal equipment is an important issue. In addition, many small to medium-scale earthquakes occur in Taiwan every year. Although those earthquakes will not damage high-tech factories, the seismic force might be amplified by the building structure, so the equipment often requires to be shut down for inspection and even cause some losses. In view of this, this research aims to develop an active isolation system for equipment that can effectively isolate small to medium earthquakes without being damaged due to excessive design earthquake levels. When subjected to an earthquake, the movement of the isolation sliding is controlled by the actuator, so that the seismic impact can be isolated. And the developed active isolation system can be used in combination with some commonly used micro-vibration isolation devices, so it is also suitable for non-rigid equipment. In this study, an easy-to-implement control algorithm based on the principle of skyhook isolation control is developed to realize a skyhook active isolation system. Furthermore, the required digital integral filter can be incorporated in the model, so the direct output feedback and parameter iterative update method can be applied to optimaldesign the control law and the stability is ensured. Because the active control can adopt displacement or speed servo control to overcome the friction, it can more effectively control the absolute acceleration level of the equipment for small to medium-scale earthquakes. Moreover, the developed active control law measures the input acceleration of the base excitation, the damping ratio of the system can be greatly increased by the control law without affecting the isolation effect. So the active isolation system will not easily react by unexpected external forces. In addition, if the displacement or speed of the active isolation layer is too large, the control law can be adjusted in real time to reduce the active vibration isolation effect. The speed of the isolation system is then immediately reduced to limit the travel of the stroke of active isolation layer, thereby avoiding collision failure. Finally, the active isolation system will be developed into bi-directional for practical use. After this project, it is expected to provide an effective solution for high-tech factory equipment to overcome earthquake hazards.