STACIS
2100 Piezoelectric Isolation System - Installation & Operation Manual
P/N 96-28765-01
Page 5 of 43
1 Principle of Operation
STACIS
is a high-bandwidth, high-gain active vibration isolation system. It provides very high vibration
isolation performance without introducing a low-stiffness isolation system (such as traditional air
isolators). The high-stiffness “hard mount” feature of STACIS
provides excellent position stability and
low susceptibility to external noise forces, giving facility engineers and researchers flexibility in locating
equipment in the manufacturing and laboratory area.
The STACIS
system is based on a central controller with three or more individual isolators. Each
isolator contains three axes of active isolation (X, Y, and Z). When three or more isolators are combined,
the result is full six degree-of-freedom vibration isolation for the supported payload. Although at first
glance the system seems over-constrained, the patented topology of STACIS
allows the isolators to act
independently of each other without conflict. Installation generally requires no special tuning, and once
installed the system is maintenance-free.
Each STACIS
isolator contains a small “intermediate mass” supported in three axes by a set of five
piezoelectric (PZT) actuators. Three seismic sensors measure the translational motions of this mass.
This signal is filtered and fed back to the PZTs by a high voltage amplifier (HVA). A ~20Hz, highly
damped rubber isolator (also internal to the isolator) couples the intermediate mass to the supported
payload. The active feedback loop provides isolation between 0.6 and 150Hz, with a peak in isolation
around 10Hz. As the active isolation starts to reduce above 10Hz, the passive isolator takes over. An
example of the resulting vibration isolation performance is shown below
1
:
Figure 1: Vertical and Horizontal Transmissibility for STACIS
2100
TMC’s DC-2000 Digital Controller is used to implement sophisticated non-linear feedback algorithms.
These ensure the isolation system performs well in extreme circumstances such as deep saturation and
1
The horizontal and vertical transmissibility was measured on a special shaker table with micron-level input. The isolated mass
was granite. Actual performance will vary depending on the nature of the floor and payload.
