Robust and precise control of piezoelectric actuators is quite challenging due to the existence of strong hysteresis nonlinearities. In this paper, a control strategy is proposed based on the uncertainty and disturbance estimator (UDE) to improve the performance of the positioning control of piezoelectric actuators. Compared to the existing hysteresis inversion based or other robust control strategies, the UDE-based controller can achieve excellent positioning precision without the knowledge of the bound and shape of hysteresis. Simulation results are presented to illustrate the effectiveness of the UDE-based controller, where the system dynamics of the piezoelectric actuator are characterized by a second order linear system preceded by a symmetric or an asymmetric generalized Prandtl-Ishlinskii (GPI) input hysteresis model. The extraordinary capability of the UDE-based controller is further demonstrated on other smart material-based actuators, e.g., magnetostrictive, shape memory alloys (SMA), where the hysteresis is characterized by a saturated GPI model.