Dynamics, load balancing, and modal control of piezoelectric tube actuators

In piezoelectric positioning systems the achievable bandwidth is often limited by weakly damped resonant modes. System performance may be improved by avoiding the excitation of these modes. If sufficient mechanical damping is present this can be done by shifting resonant modes towards anti-resonant modes through manipulation of the mechanical boundary conditions. In a second approach the anti-resonances may be shifted towards the resonances by the application of modal actuation. Using this method the excitation of the second and higher order modes can be avoided by adjusting the distribution of actuation forces. This paper investigates and compares the application of modal control techniques in systems that are based on piezoelectric tube actuators such as atomic force microscopes.