2017 Volume 6 Issue 5 Pages 320-327
Electro-hydrostatic actuators (EHAs) are hydraulic actuators with high power-to-weight ratios that exhibit low energy loss. Thus far, methods for determining the characteristics and parameters of EHAs have not been fully established. Therefore, modeling methods for EHA are in demand. EHAs are driven by servomotors on the motor-side and hydraulic motors on the load-side, and therefore, the actuators are expected to experience sympathetic vibrations. Thus, EHAs can be considered as systems in which two rigid objects are connected to one another with a low-rigidity shaft such as a spring. The occurrence of resonance in EHAs has not yet been discussed because of difficulties with hydraulic systems. One major problem is the large friction in hydraulic motors. We apply a feedback modulator for friction compensation to enable the experimental identification of characteristics. Assuming that EHAs experience two-inertia resonance, the parameters of the motors can be calculated. In addition, vibration-suppression techniques for two-inertia systems can be applied to EHAs. This study proposes the application of a two-inertia model to suppress vibrations in EHAs and verify their dynamic characteristics.
