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Hydraulic machinery

About: Hydraulic machinery is a(n) research topic. Over the lifetime, 34190 publication(s) have been published within this topic receiving 153453 citation(s). The topic is also known as: hydraulic equipment & fluid energy machine.

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01 Jan 1991
Abstract: Hydraulic Fluids. Fluid Flow Fundamentals. Hydraulic Pumps and Motors. Hydraulic Control Valves. Hydraulic Power Elements. Electrohydraulic Servovalves. Electrohydraulic Servomechanisms. Hydromechanical Servomechanisms. Nonlinearities in Control Systems. Pressure and Flow Control Valves. Hydraulic Power Supplies. Index.

2,041 citations

22 Sep 1983
Abstract: © An apparatus for applying surgical fasteners to tissue is disclosed. The apparatus includes an actuator, an applicator section for applying the fasteners and a transversely flexible shaft connecting the applicator and the actuator. The actuator and applicator preferably each contain a hydraulic fluid chamber. The chambers communicate via a hydraulic line contained in the flexible shaft. Actuation of the instrument causes movement of a piston in the applicator fluid chamber, which causes application of the fasteners. A similar second hydraulic system is preferably provided for adjusting the axial position of an anvil used to clinch the fasteners. The two hydraulic control systems are operable wholly independently of each other, permitting precise control of the anvil pressure on the tissue.

756 citations

Journal ArticleDOI
Abstract: The latest advances in electric and electronic aircraft technologies from the point of view of an "all-electric" aircraft are presented herein. Specifically, we describe the concept of a "more electric aircraft" (MEA), which involves removing the need for on-engine hydraulic power generation and bleed air off-takes, and the increasing use of power electronics in the starter/generation system of the main engine. Removal of the engine hydraulic pumps requires fully-operative electrical power actuators and mastery of the flight control architecture. The paper presents a general overview of the electrical power generation system and electric drives for the MEA, with special regard to the flight controls. Some discussion regarding the interconnection of nodes and safety of buses and protocols in distributed systems is also presented

706 citations

Journal ArticleDOI
Abstract: High-performance robust motion control of single-rod hydraulic actuators with constant unknown inertia load is considered. The two chambers of a single-rod actuator have different areas, so the dynamic equations describing the pressure changes in them cannot be combined into a single load pressure equation. This complicates controller design since it not only increases the system dimension but also brings in the stability issue of the added internal dynamics. A discontinuous projection-based adaptive robust controller (ARC) is constructed. The controller takes into account not only the effect of parameter variations coming from the inertia load and various hydraulic parameters but also the effect of hard-to-model nonlinearities such as uncompensated friction forces and external disturbances. It guarantees a prescribed output tracking transient performance and final tracking accuracy in general while achieving asymptotic output tracking in the presence of parametric uncertainties. In addition, the zero error dynamics for tracking any nonzero constant velocity trajectory is shown to be globally uniformly stable. Experimental results are obtained for the swing motion control of a hydraulic arm and verify the high-performance nature of the proposed strategy. In comparison to a state-of-the-art industrial motion controller, the proposed algorithm achieves more than a magnitude reduction of tracking errors. Furthermore, during the constant velocity portion of the motion, it reduces the tracking errors almost down to the measurement resolution level.

503 citations

Journal ArticleDOI
Abstract: The economic viability of a wave energy converter depends largely on its power take-off system. Active control of the power take-off is necessary to maximise power capture across a range of sea-states and can also improve survivability. The high force, low speed regime of wave energy conversion makes it a suitable application for high-pressure hydraulics. This paper describes the hydraulic power take-off system employed in the Pelamis wave energy converter. The process of the system's development is presented, including simulation and laboratory tests at 1/7th and fullscale. Results of efficiency measurements are also presented.

461 citations

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