Multi-axis vibration isolation using different active techniques of frequency reduction

This paper demonstrates a new idea for vibration isolation. Two different techniques of frequency reduction are presented here; the first technique depends on using an active embedded control system with proportional plus integral compensator to reduce the stiffness and corner frequency of the isolator in an active state while keeping high rigidity in a passive state. This type of isolation has proven the ability to reduce the frequency modes to about 50% of the natural frequencies in a passive state. The second technique is based on using phase lead and lag compensators on the unity gain points of the open-loop transfer function. This document will concentrate on single axis isolation although the mentioned isolator can be used as one active leg (strut) in six-axis isolators (Stewart platforms). The experimental results show as well as the simulation ones that these frequency reduction techniques have high performance on the discussed single-axis systems which makes it promising to be applied on multi-axis systems.