  An adaptive system for the suppression of vibration transmission using a
single piezoelectric actuator shunted by a negative capacitance circuit is
presented. It is known that using negative capacitance shunt, the spring
constant of piezoelectric actuator can be controlled to extreme values of zero
or infinity. Since the value of spring constant controls a force transmitted
through an elastic element, it is possible to achieve a reduction of
transmissibility of vibrations through a piezoelectric actuator by reducing its
effective spring constant. The narrow frequency range and broad frequency range
vibration isolation systems are analyzed, modeled, and experimentally
investigated. The problem of high sensitivity of the vibration control system
to varying operational conditions is resolved by applying an adaptive control
to the circuit parameters of the negative capacitor. A control law that is
based on the estimation of the value of effective spring constant of shunted
piezoelectric actuator is presented. An adaptive system, which achieves a
self-adjustment of the negative capacitor parameters is presented. It is shown
that such an arrangement allows a design of a simple electronic system, which,
however, offers a great vibration isolation efficiency in variable vibration
conditions.
