Abstract : This paper deals with design, performances comparison and experimental validation of H-infinity (H∞) and discrete time RST position controllers for a Traveling Wave Ultrasonic Motor (TWUM) which is dedicated to robotic applications. The proposed positioning system shows high precision levels of piezoelectric motor without additional hysteresis and dead zone compensation systems. Moreover, the perturbation rejection capability and the robustness to motor parameters variation are guaranteed. The synthesis procedure of robust H∞ and RST position controllers is detailed. The performances of the proposed controllers are validated by simulation and experimental results.