A method of precisely controlling the position of a hydraulic actuator using an on/off valve is developed. Since valves exhibit little power loss when they are fully open or fully closed, the proposed system is more efficient than throttling valve control and can achieve flow variation without the expense or bulk of a variable displacement pump. Mating a pulse-width-modulated (PWMed) on/off valve with a fixed displacement pump and a smoothing accumulator creates a software enabled variable displacement pump. A drawback of using digital valve control for hydraulic systems is that the relatively low speed of the currently available switching valves results in a significant ripple in the pressure and flow rate. We propose a solution to this problem by using a throttling valve to shield the actuator from the ripple in the output. This creates an effective load sensing system with the throttling valve used only to provide a small known pressure drop between the supply and the load. This approach is significantly more efficient than the conventional technique of using throttling to vary the full flow. This paper presents an averaged model of the system, a nonlinear controller to achieve position control of an actuator and a simulation based study of the effectiveness of the controller.
|Original language||English (US)|
|Title of host publication||Design, Analysis, Control and Diagnosis of Fluid Power Systems|
|Publisher||American Society of Mechanical Engineers (ASME)|
|Number of pages||9|
|State||Published - 2007|
|Event||ASME 2007 International Mechanical Engineering Congress and Exposition, IMECE 2007 - Seattle, United States|
Duration: Nov 11 2007 → Nov 15 2007
|Name||ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)|
|Other||ASME 2007 International Mechanical Engineering Congress and Exposition, IMECE 2007|
|Period||11/11/07 → 11/15/07|
Bibliographical notePublisher Copyright:
Copyright © 2007 by ASME.