Abstract
Self-contained hydraulic cylinders have gained popularity in the recent years but have not been implemented for high power articulated hydraulic manipulators. This paper presents a novel concept for an electro-hydrostatic actuator applicable to large hydraulic manipulators. The actuator is designed and analyzed to comply with requirements such as load holding, overload handling, and differential flow compensation. The system is analyzed during four quadrant operation to investigate energy efficiency and regenerative capabilities. Numerical simulation is carried out using path control and 2DOF anti-swing of a hydraulic crane as a load case to illustrate a real world scenario. A comparison with traditional valve-controlled actuators is conducted, showing significantly improved efficiency and with similar dynamic response, as well as the possibility for regenerating energy.
Highlights
There has been a trend in the recent years of replacing hydraulic drives with electric drive systems. This more-electric approach expects to deliver higher efficiencies with similar or better dynamic performance, and it has been driven by the decreasing cost of variable frequency drives (VFDs), development of high torque permanent magnet synchronous motors (PMSMs), and advanced motor control
The purpose of this paper is to present a novel concept for an electro-hydrostatic actuators (EHAs) as an alternative design to what is found in the provided references
While not exclusive to EHAs, the use of one servomotor per actuator eliminates the problem of flow sharing typically found in valve-controlled systems, meaning each actuator can run at full power at all times
Summary
There has been a trend in the recent years of replacing hydraulic drives with electric drive systems. This more-electric approach expects to deliver higher efficiencies with similar or better dynamic performance, and it has been driven by the decreasing cost of variable frequency drives (VFDs), development of high torque permanent magnet synchronous motors (PMSMs), and advanced motor control. Traditional hydraulic systems are often driven by a constant speed induction motor and use hydraulic valves to control the motion of the system. While some of the performance gain of electro-hydrostatic actuators (EHAs) comes from replacing the large size, high inertia, direct-on-line induction motor with an inverter driven high performance. The EHAs require electric power and are applicable in the following use cases:
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