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.

A Novel Trans-Scale Precision Positioning Stage Based on the Stick-Slip Effect

2012 ◽  
Vol 2 (2) ◽  
pp. 1-14 ◽  
Author(s):  
Bowen Zhong ◽  
Liguo Chen ◽  
Zhenhua Wang ◽  
Lining Sun
Keyword(s):  
Friction Model ◽  
Slip Effect ◽  
Precision Positioning ◽  
Stick Slip ◽  
Kinematics Model ◽  
Lugre Friction Model ◽  
Positioning Stage ◽  
Simulation Results ◽  
Relationship Of ◽  
The Relationship

This article focuses on developing a novel trans-scale precision positioning stage based on the stick-slip effect. The stick-slip effect is introduced and the rigid kinematics model of the stick-slip driving is established. The forward and return displacement equations of each step of the stick-slip driving are deduced. The relationship of return displacement and the acceleration produced by friction are obtained according to displacement equations. Combining with LuGre friction model, the flexible dynamics model of the stick-slip driving is established and simulated by using Simulink software. Simulation results show that the backward displacement will reduce with the acceleration of the slider produced by dynamic friction force, the rigid kinematics model is also verified by simulation results which are explained in further detail in the article.

scholarly journals Development and Evaluation of Energy-Saving Electro-Hydraulic Actuator

Actuators ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 302
Author(s):  
Triet Hung Ho ◽  
Thanh Danh Le
Keyword(s):  
Mathematical Model ◽  
Energy Consumption ◽  
Energy Saving ◽  
Energy Recovery ◽  
Hydraulic Systems ◽  
Hydraulic Actuator ◽  
High Effectiveness ◽  
Simulation Results ◽  
The Mathematical Model ◽  
Insight Into

This paper will develop a novel electro-hydraulic actuator with energy saving characteristics. This system is able to work in differential configurations through the shifting algorithm of the valves, meaning that this developed system can be adjusted flexibly to obtain the desirable working requirements including the high effectiveness of energy recovery from the load, high velocity or torque. Instead of establishing the mathematical model for the purpose of the dynamic analysis, a model of the developed actuator is built in AMESim software. The simulation results reveal that the system is able to save approximately 20% energy consumption compared with a traditional without energy recovery EHA. Furthermore, to evaluate the accuracy of the model, experiments will be performed that prove strongly that the experimental results are well matched to the results attained from the simulation model. This work also offers a useful insight into designing and analyzing hydraulic systems without experiments.

Compensation of Stick-Slip Phenomenon in an Electrical Actuator

2003 ◽  
Vol 15 (4) ◽  
pp. 398-405 ◽  
Author(s):  
R. Merzouki ◽  
◽  
J. C. Cadiou ◽  
N. K. M'Sirdi
Keyword(s):  
Friction Force ◽  
Static Friction ◽  
Adaptive Controller ◽  
Nonlinear Observer ◽  
Convergence To Equilibrium ◽  
Dynamic Friction ◽  
Slip Effect ◽  
Stick Slip ◽  
Electrical Actuator ◽  
Slip Phenomenon

In mechanical systems involving low-speed motion, consisting of a succession of jumps and stops, as in trained wagons or manipulated robots, control usually exhibits error when the static friction force exceeds the dynamic friction force in what is known as the stick-slip effect. We developed a nonlinear observer to determine the friction force of contact during motion and to compensate for its effect. Simulation and experimental results show global convergence to equilibrium and good performance by the adaptive controller.

Movement Modeling and Testing of a Novel Trans-Scale Precision Positioning Stage Based on the Stick-Slip Effect

2011 ◽  
Vol 225-226 ◽  
pp. 684-687 ◽  
Author(s):  
Bo Wen Zhong ◽  
Li Guo Chen ◽  
Zhen Hua Wang ◽  
Li Ning Sun
Keyword(s):  
Simulation Analysis ◽  
Friction Model ◽  
Reverse Direction ◽  
Slip Effect ◽  
Precision Positioning ◽  
Movement Model ◽  
Stick Slip ◽  
Model And Simulation ◽  
Positioning Stage ◽  
The Difference

A novel trans-scale precision positioning stage based on the stick-slip effect was developed. Combining with LuGre friction model, the flexible movement model of the stick-slip driving was established and simulated in Simulink software. Simulation analysis got the displacement and speed curve of slider and the net displacement of each step was calculated. The movement of slider lags behind the PZT actuator. The testing prototype of the stage driving by stick-slip effect was designed and the movement parameters of forward and reverse direction was tested, the results of movement model and simulation was verified by the testing datas. The problem of the difference of forward and reverse movement was proposed.

scholarly journals The effect of laser surface texturing to inhibit stick-slip phenomenon in sliding contact

2019 ◽  
Vol 11 (9) ◽  
pp. 168781401987463
Author(s):  
Hao Wang ◽  
Xuan Xie ◽  
Xijun Hua ◽  
Bifeng Yin ◽  
Hang Du ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Friction Coefficient ◽  
Machine Tools ◽  
Laser Surface Texturing ◽  
Lubricating Oil ◽  
Textured Surface ◽  
Slip Effect ◽  
Stick Slip ◽  
Adequate Amount ◽  
Slip Phenomenon

Stick-slip phenomenon in some mechanical structures, especially in machine tools, should be eliminated or inhibited, otherwise the vibration will occur and the position error will inevitably be obtained. In this study, different kinds of surface textures were carried out on the lower samples of the pin-on-disk contact. The starting process of the machine tools was simulated on an Rtec-Multi-Function Tribometer. The stick-slip phenomenon was observed in each kind of samples. However, the stick-slip phenomenon of smooth sample is larger than that of the textured samples. The bulge-textured surface shows excellent anti-stick-slip effect, and the critical stick-slip speed of bulge-textured surface is 95.9% lower than that of the smooth surface. Simultaneously, the anti-stick-slip effect of bulge-textured surface is superior to that of the dent-shaped texturing surface. What’s more, when the amount of lubricating oil is 15 mL, the standard deviation values of friction coefficient and critical speed of stick-slip phenomena (rotational speed when the standard deviation of friction coefficient is abrupt) are the lowest at different rotational speeds. It can be predicted that the bulge textures and adequate amount of lubricating oil (15 mL) can eliminate stick-slip phenomenon when processed in the surface of the machine tool because the bulge textures and adequate amount of lubricating oil can improve frictional state effectively and avoid the slip of the contact surface.

Finite Element Formulation for Prediction and Quantification of Stick-Slip Phenomenon in Down-Hole Tubular Expansion

2013 ◽  
Author(s):  
Omar S. Al-Abri ◽  
Tasneem Pervez ◽  
Sayyad Z. Qamar ◽  
Rashid Khan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Oil And Gas ◽  
Element Model ◽  
Friction Model ◽  
Stick Slip ◽  
Premature Failure ◽  
Horizontal Drilling ◽  
Finite Element Software ◽  
Slip Phenomenon

The challenges in exploration and development of unconventional oil and gas resources are enormous. The complex reservoir characteristics, and oil and gas flow regimes introduce difficulty in predicting the oil and gas in-place, recovery and production profiles, and wells placement, design and completion. Horizontal drilling and completion using centuries-old manufacturing process of tube forming resulted in producing oil and gas from large areas with smaller footprint on the surface. Though expensive but it optimizes the recovery. The in-situ diametral expansion of tubular using a solid mandrel causes permanent deformation in which the system experiences large frictional forces at mandrel/tubular interface resulting in stick-slip phenomenon. It results in varying tubular thickness and diametral eccentricity which causes structural instability in wells leading to premature failure. A finite element model describing the dynamics of stick-slip phenomenon in down-hole tubular expansion was developed. Three different set of equations; one each for stick, slip and transition phases were derived using equilibrium equations, time-dependent static friction model and velocity-dependent kinetic friction model. A switch model utilizing the zero velocity interval criterion was used to define stick, slip and transition phases. The newly developed model was implemented in the finite element model by means of two user-defined subroutines namely VFRIC and VDLOAD in commercial finite element software ABAQUS. Experimental and simulation results agree well for expansion force, wall thickness reduction and tubular length shortening. It was found that the thickness variation is the most critical parameter due to its effect in lowering collapse strength of expanded tubular. Parametric study investigations showed that the effect of this phenomenon may possibly be minimized by manipulating mandrel geometry, contact conditions, and/or mandrel speed.

Investigation of the Helmholtz Motion of a Violin String: A Finite Element Approach

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Özge Akar ◽  
Kai Willner
Keyword(s):  
Finite Element ◽  
Slip Effect ◽  
Friction Characteristic ◽  
Stick Slip ◽  
Characteristic Curves ◽  
Finite Element Approach ◽  
Element Approach ◽  
The Impact ◽  
Slip Phenomenon

Abstract In the context of this work, a violin string motion is examined using a finite element approach. The string is formulated via ideal string elements and is bowed at one point on the string; hence, there is a nodal contact between the bow and the string. The bow movement induces the stick-slip effect, which is the cause for the violin string sound. The present paper aims at the investigation of the stick-slip phenomenon of bowed strings, considering well-known bowed string effects like the Helmholtz corner modulation, the Schelleng ripples, and the flattening effect. One key element that is used in this work is the Schelleng diagram, which indicates the “perfect” bow force depending on the bowing position. Within these parameters, the Helmholtz motion is carried out. Additionally, different friction characteristic curves are applied in order to study the impact of the rosin on the string motion.

Theoretical and Experimental Investigation of Hydraulic Actuator Interaction in the Dynamics of a Rotating Flexible Beam

1994 ◽  
Vol 116 (1) ◽  
pp. 113-119 ◽  
Author(s):  
M. J. Panza ◽  
R. W. Mayne
Keyword(s):  
Mathematical Model ◽  
System Dynamics ◽  
Dynamic Performance ◽  
Hydraulic Cylinder ◽  
Flexible Beam ◽  
Hydraulic Actuator ◽  
Dimensionless Parameters ◽  
Beam Equations ◽  
The Mathematical Model

The dynamic interaction between a rotating flexible beam and a hydraulic cylinder actuator driving the beam along its length is presented. A mathematical model is developed combining the dynamics of a continuous beam, discretized by modal analysis, to the system dynamics of the actuator. Fully coupled actuator and beam equations are generalized by introducing dimensionless parameters. The interaction between actuator and flexible beam is investigated via a reduced order model, eigenvalue analysis, and numerical simulations. Experimental results are presented to show the quality of the mathematical model and the effect of actuator parameter selection on system dynamics and beam vibration. Actuator selection concepts based on dimensionless parameters are given to provide systems with desirable dynamic performance and suppressed beam vibrations.

scholarly journals Studying friction while playing the violin: exploring the stick–slip phenomenon

2017 ◽  
Vol 8 ◽  
pp. 159-166 ◽  
Author(s):  
Santiago Casado
Keyword(s):  
Atomic Force Microscopy ◽  
Shear Stress ◽  
Slip Effect ◽  
Stick Slip ◽  
Force Microscopy ◽  
Atomic Force ◽  
Stringed Instrument ◽  
Microscopy Characterization ◽  
Atomic Force Microscopy Characterization ◽  
Slip Phenomenon

Controlling the stick–slip friction phenomenon is of major importance for many familiar situations. This effect originates from the periodic rupture of junctions created between two rubbing surfaces due to the increasing shear stress at the interface. It is ultimately responsible for the behavior of many braking systems, earthquakes, and unpleasant squeaky sounds caused by the scratching of two surfaces. In the case of a musical bow-stringed instrument, stick–slip is controlled in order to provide well-tuned notes at different intensities. A trained ear is able to distinguish slight sound variations caused by small friction differences. Hence, a violin can be regarded as a perfect benchmark to explore the stick–slip effect at the mesoscale. Two violin bow hairs were studied, a natural horse tail used in a professional philharmonic orchestra, and a synthetic one used with a violin for beginners. Atomic force microscopy characterization revealed clear differences when comparing the surfaces of both bow hairs, suggesting that a structure having peaks and a roughness similar to that of the string to which both bow hairs rubbed permits a better control of the stick–slip phenomenon.

On/Off Valve Based Position Control of a Hydraulic Cylinder

2007 ◽  
Author(s):  
Michael B. Rannow ◽  
Perry Y. Li
Keyword(s):  
Position Control ◽  
Hydraulic Cylinder ◽  
Conventional Technique ◽  
Hydraulic Systems ◽  
Hydraulic Actuator ◽  
Nonlinear Controller ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Averaged Model ◽  
Valve Control

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.

Sign in / Sign up

Export Citation Format

Share Document