Performance of piezo-stacks for a piezoelectric hybrid actuator by experiments

Abstract

Piezoelectric-hydraulic actuator is a hybrid device that consists of a hydraulic pump driven by piezoelectric stacks coupled with a conventional hydraulic cylinder and a set of fast-acting valves. Nowadays, such hybrid actuators are being researched and developed actively in many developed countries by requirement of high performance and compact flight system. In this research, operation principle and performance testing of the hybrid actuator were introduced. Two types of piezo-stacks are selected for experimental performance testing to identify the factors of piezo-stack which affect the performance of the hybrid actuator. The performance of piezo-stacks due to electrical power supply and self-heating was considered. Output no-load velocities and blocked force were measured on performance testing. The results showed that the maximum blocked force was 346 N and no-load velocity was 101 mm/s, resulting in maximum output power of 8.74 W at 1000 V applied voltage and 250 Hz pumping frequency.

Experimental Study on the Performance of a Bidirectional Hybrid Piezoelectric-Hydraulic Actuator

“…The reason for the poor performance was found to be the result of a vacuum problem. The system of the bidirectional piezoelectric hybrid actuator is more complicated than the unidirectional actuator system [7]. When the bias pressure was included, an air bubble developed in the oil.…”

“…However, a high bias pressure disturbs the performance of the actuator, so it should be added moderately. In this study, the bulk modulus was chosen as 0.2GPa with the assumption of 2MPa bias pressure and 1% air contents [7].…”

“…Therefore, the correct selection of a smart structure for an actuator depends on the purpose of attaining a maximum blocking force or maximum output velocity. In our previous study, the PZT was used as a driving material for a unidirectional hybrid actuator to obtain a high blocking force [7]. However, the blocking force was not as high as expected.…”

“…In this research, the aim was to develop a bidirectional piezoelectric-hydraulic actuator with a large blocking force based on the design of a unidirectional hybrid actuator [7]. In order to improve the blocking force, the dimensions of the pump chamber and cylinder were redesigned.…”

“…The no-load testing of this actuator showed that the maximum output velocity was 330mm/s at 700Hz driving frequency. In a recent study, Zhefeng Xuan et al developed an integrated hybrid hydraulic actuator driven by piezo-stacks [7]. Two types of piezo-stacks, P-025.40P of PI, Inc. and PSt 1000/25/80 of Piezomechanik, were tested.…”