Performance Of Vibration Control System Research Articles

Multi-Objective Robust Active Vibration Control of an Arbitrary Thick Piezolaminated Beam

A multi-objective mixed / robust output feedback control synthesis with additional regional pole placement constraints in a linear matrix inequalities (LMI) framework is adopted for active vibration suppression of a simply supported, arbitrary thick, piezolaminated beam with continuously integrated sensor and actuator layers, in the face of high frequency unmodeled dynamics (residual uncertainties) and external disturbance. The structural formulation is based on a spatial state-space approach using the exact linear two-dimensional piezoelasticity theory and involving local/global transfer matrices. To assist control system design, subspace-based multivariable system identification is carried out by using the first four modes in the frequency range of 0–4000 rad/sec for control purpose, while the remaining high frequency (residual) modes in the control bandwidth are left as the uncertainty of modeling. The dynamic performance of vibration control system is demonstrated in both frequency and time domains for a three-layered sandwich beam including three pairs of piezoelectric actuator/sensor (Ba2NaNb5O15/PZT4) segments asymmetrically collocated on both sides of an orthotropic core for two different types of loading (i.e., impulsive load and random disturbance). The accuracy of dynamic analysis is established with the aid of a commercial finite element package and the data available in the literature.

Modeling and compensation of piezoceramic actuator hysteresis for helicopter vibration control

Hysteresis in piezoceramic materials causes considerable complications in the use of piezo actuators in applications, such as vibration control. In this study, the classical Preisach model is used to characterize the hysteresis in a piezostack actuator used to move a trailing-edge flap for helicopter vibration control. The hysteresis in the actuator is primarily due to material nonlinearity and to a lesser extent due to losses in the amplification mechanism. Most helicopter vibration control studies ignore the effect of the hysteresis on the actuator performance. The desired motion of the flap for maximum reduction in vibration is determined using an aeroelastic analysis of the helicopter. Numerical results indicate that complete compensation of actuator hysteresis can result in up to 90% reduction in helicopter vibrations. The performance of the vibration control system deteriorates considerably when the actuator is represented by a linear model or when the compensator is based only on the primary material hysteresis of the actuator. Complete compensation of both material and mechanical hysteresis in the actuator is therefore critical to the performance of the trailing-edge flap vibration control system in a helicopter.