In order to study the numerical control (NC) servo press hydraulic control system and its control algorithm. The numerical control servo press performance and control principle of hydraulic control system are analyzed. According to the flow equation of the hydraulic control valve, hydraulic cylinder flow continuity equation and the force balance equation of the hydraulic cylinder with load pres...

This paper details the new design and dynamic simulation of an electro-hydraulic camless engine valve actuator (EH-CEVA) and experimental verification with lift position sensors. In general, camless engine technologies have been known for improving fuel efficiency, enhancing power output, and reducing emissions of internal combustion engines. Electro-hydraulic valve actuators are used to elimin...

In mobile hydraulic machines, like excavators, backhoe loaders, wheel loaders, and forklift trucks, haptic human-machine interfaces are not in use. Today, the machines are operated with mechanical-hydraulic joysticks. Each joystick axis controls a single hydraulic actuator. This leads to not very easy to use operational concepts. Since electrohydraulic systems with electronic joysticks are avai...

This paper describes the development of linear parameter varying (LPV) models and an LPV-H∞ controller for one degree of freedom (DoF) electro-hydraulic systems. A virtual set-up consists of a hydraulic actuator driven by a servovalve and supplied from a constant-pressure power unit. The LPV models are derived based on two techniques: black-box modeling and the analytical description of the sys...

The present hydraulic variable-pitch mechanism of wind turbine uses three hydraulic cylinders to drive three crank and connecting rod mechanisms respectively; the blades are moved with the cranks. The hydraulic variable-pitch mechanism has complex structure, occupies a lot of space and its maintenance is trouble. In order to make up for the shortcomings of hydraulic cylinder variable-pitch syst...

This paper presents a unified and systematic assessment of ten position control strategies for a hydraulic servo system with single-ended cylinder driven by a proportional directional control valve. We aim at identifying those methods that achieve better tracking, have a low sensitivity to system uncertainties, and offer a good balance between development effort and end results. A formal approa...

This paper studies the energy-saving adaptive robust motion control of a single-rod hydraulic cylinder through the use of programmable valves—a unique combination of five proportional cartridge valves. The programmable valves decouple the meter-in and meter-out flows and provide true cross port regeneration flow which in turn allows tremendous control flexibility. Although at the expense of con...

This paper presents the theoretical and experimental researches performed by the authors in order to design a digital control system for electrohydraulic servomotors. The system contains a digital control module and two position servomechanisms. A mathematical approach was developed for obtaining a mathematical model describing the whole control system. The dynamic performance of this system wa...

Development of reliable power-by-wire actuation systems for both aeronautical and space applications has been sought recently to eliminate hydraulic systems from aircraft and spacecraft and thus improve safety, efficiency, reliability, and maintainability. The Electrically Powered Actuation Design (EPAD) program was a joint effort between the Air Force, Navy, and NASA to develop and fly a serie...