Design and identification of a double-acting piezoelectric-hydraulic hybrid actuator

Abstract

Traditional single-acting piezoelectric-hydraulic hybrid actuators usually have the problem of inertial force caused by flow pulsation of the liquid, which degrades their output performance. To suppress or solve the associated inertial force and enhance its output capabilities, this paper proposes a new type of double-acting piezoelectric-hydraulic hybrid actuator with four check valves acting as mechanical diodes. The new hybrid actuator was fabricated and its output performance was tested. When the voltage is 700 Vp-p and the bias pressure is 2 MPa, the pulsation rates δ of the new actuator at 400 Hz, 500 Hz and 600 Hz are 2.29, 2.08 and 1.78, respectively, while δ of the single-acting hybrid actuator under the same conditions are 10.98, 11.05 and 17.12. Therefore, the liquid pulsation rate of the new hybrid actuator is significantly reduced, which is beneficial for improving the flow uniformity and weakening the influence of inertial force on the hybrid actuator. This strategy ultimately leads to a maximum no-load velocity of 168.1 mm/s at 600 Hz and a maximum blocking force of 141 N at 450 Hz for the new hybrid actuator. In addition, this strategy has the potential to be used in other electrohydrostatic actuators to improve their performance.