On/Off Valves Synchronization and Reliability Evaluation of a Digital Hydraulic Actuator

2020 ◽  
Author(s):  
Ivan J. Mantovani ◽  
Heitor A. Kagueiama ◽  
Artur T. de C. Gama ◽  
Alessandro Dell' Amico ◽  
Petter Krus ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Flight Control ◽  
Response Times ◽  
Reliability Evaluation ◽  
Similar Response ◽  
Efficiency Gain ◽  
Hydraulic Systems ◽  
Hydraulic Actuator ◽  
Opening And Closing ◽  
Control Surfaces

Abstract The development of actuators for flight control surfaces based on electrical technologies had a breakthrough in the last decade. Nevertheless, servo-hydraulic systems are still widely used. Servo Hydraulic Actuators (SHA) have the advantages of precise positioning, high dynamic response and being a jam-free solution in case of failures, but they present low energy efficiency. Digital hydraulics has become a topic of interest in improving energy efficiency in the fluid power community. A Digital Hydraulic Actuator (DHA) for aircraft is being developed to be used in primary flight control surfaces. The DHA concept is based on secondary control with multi-chamber cylinders and shows an energy efficiency gain with a similar response when compared to SHA. However, the opening and closing times of on/off valves are different and uncertain. These aspects may result in short circuits, bringing energy losses, or in blocked chambers, which may cause pressure peaks or cavitation. Consequently, the DHA system may have a lower energy efficiency or presents vibration due to fluid blocking. The present paper presents a solution for these issues and the reliability evaluation of the DHA. The opening and closing times issues are addressed using the synchronization between on/off valves through a method to find the correct time for valve opening control. As a result, the synchronization of pressure shifting without knowledge of the response times of on/off valves was accomplished. Moreover, when used periodically, this method can estimate future failures in valves due to a change of the required time delay. In order to evaluate the system reliability, FTA models were developed considering valve and pressure line failures, modelling how the failures affect force availability to move the control surfaces. The resulting FTAs were reduced to the minimum cut-sets that lead to force profiles that are insufficient for a safe flight and also may lead to an aircraft crash. Considering that the on/off valves have similar failure rates to those of servo valves, the results show that DHA and SHA have comparable reliability levels.

Modeling and Analysis of a Digital Hydraulic Actuator for Flight Control Surfaces

2021 ◽  
Author(s):  
R. S. Lopes ◽  
M. P. Nostrani ◽  
L. A. Carvalho ◽  
A. Dell’Amico ◽  
P. Krus ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Flight Control ◽  
Data Model ◽  
Flight Performance ◽  
Hydraulic Actuator ◽  
Hydraulic Power ◽  
Fighter Aircraft ◽  
Modeling And Analysis ◽  
Modeling Process ◽  
Control Surfaces

Abstract This paper presents the design and modeling process of a flight control actuator using digital hydraulics and a performance analysis that compares the proposed solution and the Servo Hydraulic Actuator (SHA) on a fighter aircraft model. The proposed solution is named Digital Hydraulic Actuator (DHA) and comprises the use of a multi-chamber cylinder controlled by on/off valves and different pressures sources provided by a centralized hydraulic power unit, as proposed in the Fly-by-Wire (FbW) concept. The analyses were carried out using the Aero-Data Model in a Research Environment (ADMIRE), which was developed for flight performance analysis. The actuators were modeled using the software Matlab/Simulink® and Hopsan. They were applied to control the aircraft elevons in a flight mission close to the aircraft limits, to evaluate the actuator’s behavior and energy efficiency. The results show a reduction in energy dissipation up to 22.3 times when comparing the DHA with the SHA, and despite the overshooting and oscillations presented, the aircraft flight stability was not affected.

A New Type of Hydraulic Actuator Using Electrorheological Fluids

1999 ◽  
Vol 13 (14n16) ◽  
pp. 2176-2182 ◽  
Author(s):  
Eckhard Wendt ◽  
Klaus W. Büsing
Keyword(s):  
Silicone Oil ◽  
Response Times ◽  
Electrical Signal ◽  
Electrorheological Fluids ◽  
Shear Stresses ◽  
Hydraulic Fluid ◽  
High Shear ◽  
Hydraulic Systems ◽  
Hydraulic Actuator ◽  
Inorganic Particles

Electrorheological Fluids (ERF) are usually used in semi active damping elements, e.g. shock absorbers or engine mounts because of their continuously controllable shear stress. A totally new field of application may be achieved, if an ERF is used as a hydraulic fluid and not only as a control medium. In this case a fundamental need is the capability to produce a volume flow by using normal hydraulic pumps, e.g. gear pumps. The ERF and the hydraulic components both must have a long lifetime without unusual wear. Bayer AG has developed an ERF based on soft crosslinked PU-particles dispersed in silicone oil. These ERF are characterised by a low basic viscosity, a high ER-effect and a moderate conductivity. Compared with previous ERF where hard inorganic particles were used, the new fluid is not abrasive. It is foremostly this characteristic which gives the possibility of using the ERF in hydraulic systems with high shear rates and high shear stresses. The usage of ERF as hydraulic fluid allows the construction of proportional valves without mechanically driven parts. The control of the pressure drop over the valves is realised directly by an electrical signal. It is possible to realise actuators with very fast response times since the reaction time of ERF is within milliseconds. For demonstration purpose Bayer AG has built an actuator which is controlled by an electrorheological valve-block. The calculation of the dimension of this actuator and the valves will be shown and the realised response time will be demonstrated.

scholarly journals User Clustering and Power Allocation for Energy Efficiency Maximization in Downlink Non-Orthogonal Multiple Access Systems

2021 ◽  
Vol 11 (2) ◽  
pp. 716
Author(s):  
Ruibiao Chen ◽  
Fangxing Shu ◽  
Kai Lei ◽  
Jianping Wang ◽  
Liangjie Zhang
Keyword(s):  
Energy Efficiency ◽  
Power Allocation ◽  
Multiple Access ◽  
Spectrum Efficiency ◽  
Lagrangian Multiplier ◽  
Efficiency Gain ◽  
Optimal Power Allocation ◽  
Optimal Power ◽  
User Clustering ◽  
Cluster Dynamic

Non-orthogonal multiple access (NOMA) has been considered a promising technique for the fifth generation (5G) mobile communication networks because of its high spectrum efficiency. In NOMA, by using successive interference cancellation (SIC) techniques at the receivers, multiple users with different channel gain can be multiplexed together in the same subchannel for concurrent transmission in the same spectrum. The simultaneously multiple transmission achieves high system throughput in NOMA. However, it also leads to more energy consumption, limiting its application in many energy-constrained scenarios. As a result, the enhancement of energy efficiency becomes a critical issue in NOMA systems. This paper focuses on efficient user clustering strategy and power allocation design of downlink NOMA systems. The energy efficiency maximization of downlink NOMA systems is formulated as an NP-hard optimization problem under maximum transmission power, minimum data transmission rate requirement, and SIC requirement. For the approximate solution with much lower complexity, we first exploit a quick suboptimal clustering method to assign each user to a subchannel. Given the user clustering result, the optimal power allocation problem is solved in two steps. By employing the Lagrangian multiplier method with Karush–Kuhn–Tucker optimality conditions, the optimal power allocation is calculated for each subchannel. In addition, then, an inter-cluster dynamic programming model is further developed to achieve the overall maximum energy efficiency. The theoretical analysis and simulations show that the proposed schemes achieve a significant energy efficiency gain compared with existing methods.

Research on the ELAC Systems of A320 Family Aircrafts

2012 ◽  
Vol 546-547 ◽  
pp. 1562-1567
Author(s):  
Kai Yin ◽  
Gang Yin ◽  
Qin Zhen Li
Keyword(s):  
Computer System ◽  
Basic Principle ◽  
Flight Control ◽  
On Line ◽  
Control Surfaces ◽  
Driving Circuit

This document introduces the basic principle of the ELAC System (Elevator Aileron Computer System) working of A320 aircrafts, and mainly, analyzes the driving circuit of the ELAC computer for the flight control surfaces. Furthermore, introduces a real fault on line maintenance, analyze it and find out the reason, give some useful advice on A320 aircraft line maintenance.

Simulacija i odstranjivanje stick-slip efekta servosistema sprovodnog aparata hidraulične turbine

2021 ◽  
Vol 23 (1) ◽  
pp. 37-41
Author(s):  
Darko Babunski ◽  
◽  
Emil Zaev ◽  
Atanasko Tuneski ◽  
Laze Trajkovski ◽  
...  
Keyword(s):  
Hydraulic Cylinder ◽  
Friction Model ◽  
Slip Effect ◽  
Hydraulic Systems ◽  
Hydraulic Actuator ◽  
Stick Slip ◽  
Hydro Turbine ◽  
Servo Mechanism ◽  
The Mathematical Model ◽  
Slip Phenomenon

Friction is a repeatable and undesirable problem in hydraulic systems where always has to be a tendency for its removal. In this paper, the friction model is presented through which the most accurate results are achieved and the way of friction compensation, approached trough technique presented with the mathematical model of a hydraulic cylinder of a hydro turbine wicket gate controlled by a servomechanism. Mathematical modelling of a servo mechanism and hydraulic actuator, and also the simulation of hydraulic cylinder as a part of a hydro turbine wicket gate hydraulic system where the stick-slip phenomenon is present between the system components that are in contact is presented. Applied results in this paper and the theory behind them precisely demonstrate under what circumstances the stick-slip phenomenon appears in such a system. The stick-slip effect is simulated using Simulink and Hopsan software and the analysis of the results are given in this paper. Removal of the stick-slip effect is presented with the design of a cascade control implemented to control the behaviour of the system and remove the appearance of a jerking motion.

scholarly journals A Self-Contained Electro-Hydraulic Cylinder with Passive Load-Holding Capability

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 292 ◽  
Author(s):  
Damiano Padovani ◽  
Søren Ketelsen ◽  
Daniel Hagen ◽  
Lasse Schmidt
Keyword(s):  
Energy Efficiency ◽  
Cost Efficiency ◽  
Tracking Error ◽  
Hydraulic Cylinder ◽  
Position Tracking ◽  
Hydraulic Systems ◽  
Practical Applications ◽  
Hydraulic Cylinders ◽  
External Loads ◽  
Boom Crane

Self-contained electro-hydraulic cylinders have the potential to replace both conventional hydraulic systems and the electro-mechanical counterparts enhancing energy efficiency, plug-and-play installation, and reduced maintenance. Current commercial solutions of this technology are limited and typically tailor-made, whereas the research emphasis is primarily on cost efficiency and power applications below five [kW]. Therefore, there is the need of developing more flexible systems adaptable to multiple applications. This research paper offers a contribution in this regard. It presents an electro-hydraulic self-contained single-rod cylinder with passive load-holding capability, sealed tank, capable of recovering energy, and scalable up to about eighty [kW]. The system implementation on a single-boom crane confirms its feasibility: The position tracking error remains well within ±2 [mm], oscillations are limited, and the overall energy efficiency is about 60 [%] during actuation. Concerning the passive load-holding devices, it is shown that both vented and non-vented pilot-operated check valves achieve the desired functioning and can hold the actuator position without consuming energy. Additional observations about the size and the arrangement of the load-holding valves are also provided. In conclusion, this paper demonstrates that the proposed self-contained cylinder can be successfully extended to several practical applications, especially to those characterized by overrunning external loads and the need of securing the actuator position.

Real Time Loading Test Rig for Flight Control Actuators Under PHM Experimentation

2018 ◽  
Author(s):  
P. Chiavaroli ◽  
A. De Martin ◽  
G. Evangelista ◽  
G. Jacazio ◽  
M. Sorli
Keyword(s):  
Flight Control ◽  
Linear Models ◽  
Angular Position ◽  
Experimental Tests ◽  
Hydraulic Actuator ◽  
Loading Test ◽  
Pressure Transducers ◽  
Non Linear ◽  
Flight Controls ◽  
Servo Actuator

The article deals with the architecture, performance, and experimental tests of a test bench for servo-actuators used in flight controls. After the state of the art on the subject, the innovative architecture of the built bench is described, in which flight control actuator under test and load actuator are not in line but mounted perpendicularly. The model of the bench actuating systems is then presented, consisting of the servo-controlled hydraulic actuator, load cell, speed transducer, angular position transducer of the coupling and pressure transducers. For each of these components the nonlinear multi-physics mechatronic model is described, according to the adopted solutions. The adopted force control algorithm is discussed, showing the integrative compensation on the action line and proportional-derivative on the feedback, with speed feedforward. The experimental tests carried out on the bench under stalled conditions are also presented, whose results concerning time and frequency responses are compared with those obtained through the linearized and non-linear numerical model. Finally, the non-linear models of the flight control actuator under test, controlled in position, and of the loading servo-actuator of the bench are joined together, and the results of various simulations are described.

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