In this paper, we present a backstepping based fuzzy logic (FL) scheme for the active control of vehicle suspension systems using the two-degrees of freedom or 1/4 car model. The full dynamics of a novel hydraulic strut are considered. The servo-valve dynamics are also included. A fuzzy logic system is used to estimate the nonlinear hydraulic strut dynamics. The backstepping fuzzy logic scheme ...

The paper aims to develop a novel pitch control system for a large wind turbine driven by a variable-speed pump-controlled hydraulic servo system. To perform practical pitch control experiments, a full-scale test rig of the hydraulic pitch control system for a 2 MW wind turbine’s blade, including a novel pitch control mechanism, a variable-speed pump-controlled hydraulic servo system, a disturb...

This study presents application of Dynamic Programming towards finding globally optimal control policies of a new, highly-efficient hydraulic elevator architecture. The architecture employs an actuator, three accumulators, and two hydraulic circuits bridged by a hydraulic transformer. An auxiliary electric motor exists only to compensate for system losses. Prior research identified a multitude ...

Pressure pulsation, created by the operation of hydraulic pumps in a fluid power system, is one of the primary causes of noise issues from hydraulic machinery. The wave energy resulting from such pulsation propagates in both the wall and the fluid of the flow pipes associated with the fluid power systems, inducing fluid borne vibration of the pipes and the consequent noise radiated from the pip...

Abstract In general two basic methods are used for controlling the velocity of a hydraulic cylinder. First by an axial variable-displacement pump for controls flow to the cylinder. This configuration is commonly known as a hydrostatic transmission. Second by proportional valve powered by a constant-pressure source, such as a pressure compensated pump, drives the hydraulic cylinder. In this stud...

Throttling loss of a hydraulic system is a major contributor to the low system efficiency. Hydraulic transformers can potentially be used as an energy efficient, throttle-less control approach for multi-actuators systems powered by a common pressure rail (CPR). The transformer transforms the input CPR pressure to the desired pressure of the actuator instead of throttling it. Regenerative energy...

A better understanding of the mechanistic basis of stomatal control is necessary to understand why modes of stomatal response differ among individual trees, and to improve the theoretical foundation for predictive models and manipulative experiments. Current understanding of the mechanistic basis of stomatal control is reviewed here and discussed in relation to the plant hydraulic system. Analy...

Both engineered hydraulic systems and plant hydraulic systems are protected against failure by resistance, reparability, and redundancy. A basic rule of reliability engineering is that the level of independent redundancy should increase with increasing risk of fatal system failure. Here we show that hydraulic systems of plants function as predicted by this engineering rule. Hydraulic systems of...