A smart structure plays a vital role in aerospace applications and robotics and other applications. It presents many challenging control problems due to their non-linear dynamic behavior. The Objective of this work is to design a controller that minimizes the structural vibration using H∞ controller. Vibration as a measured parameter has been used to evaluate model of a nonlinear process (piezoelectric actuator and sensor) at different modes .The model was generated using an ARMAX technique. By selecting appropriate weighting functions