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.

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.

Stick-Slip Behaviour of Seals With Respect to Time Dependent Friction Forces

2004 ◽  
Author(s):  
Markus Lindner ◽  
Matthias Kro¨ger ◽  
Karl Popp ◽  
Manuel Gime´nez
Keyword(s):  
Stability Analysis ◽  
Time Dependent ◽  
Dynamic Friction ◽  
Slip Effect ◽  
Stick Slip ◽  
Friction Forces ◽  
Seal Design

In the present paper dynamic friction processes in seals are investigated. The undesired stick-slip effect of these components under real technical conditions is analyzed. Starting with the basics of stick-slip vibrations the development of an advanced seal design with improved properties is presented that prevents stick-slip. Finally, an optimization based on the extensive but simple stability analysis is shown by an expanded theory of stick-slip simulations.

Dynamic Effects of Mandrel/Tubular Interaction on Downhole Solid Tubular Expansion in Well Engineering

2009 ◽  
Vol 131 (1) ◽  
Author(s):  
A. C. Seibi ◽  
A. Karrech ◽  
T. Pervez ◽  
S. Al-Hiddabi ◽  
A. Al-Yahmadi ◽  
...  
Keyword(s):  
Structural Response ◽  
Static Friction ◽  
Expansion Ratio ◽  
Thickness Reduction ◽  
Drawing Force ◽  
Expansion Process ◽  
Stick Slip ◽  
State Expansion ◽  
Threaded Connections ◽  
Slip Phenomenon

The expansion process subjects a solid tubular to large plastic deformations leading to variations in tubular thickness and length, which may result in premature and unexpected failures. It was noticed that the expansion process induces wall thickness imperfections due to excessive local plastic deformation as a result of mandrel sticking and slipping relative to the expanded tubular; such irregularities increase the probability of failure. Mandrel sticking may be the result of lack of enough lubrication, tubular surface irregularities, and the presence of welded and/or threaded connections, which require higher drawing force to push the mandrel forward. When the drawing force required to overcoming the maximum static friction and the mandrel forward motion is assured, the mandrel slips relative to the expanded tubular. This “stick-slip” phenomenon results in mandrel oscillations that affect the tubular response in terms of further reduction in thickness and may jeopardize the tubular capacity under normal operating field conditions. Therefore, the present work studies the mandrel dynamics and their effect on the tubular structural response. A mathematical model, which is an extension of the quasistatic tubular expansion analysis, has been developed to describe the dynamic friction effects of the stick-slip phenomenon. A special case of tubular expansion consisting of 25% expansion ratio of a 4/12 in. (114.3 mm) liner hanger was considered. It was found that the level of mandrel oscillations is in the order of 1–2 mm around its equilibrium position resulting in tubular thickness reduction of approximately 9% on top of its variation caused by the steady state expansion process. This increase in thickness reduction may affect the postexpansion collapse strength of the tubular.

Atomistics of Friction

2005 ◽  
Author(s):  
Motohisa Hirano
Keyword(s):  
Friction Force ◽  
Translational Motion ◽  
Static Friction ◽  
System Size ◽  
Dynamic Friction ◽  
Friction Forces ◽  
Internal Motions ◽  
Locking Mechanism ◽  
Roughness Model ◽  
Solid Bodies

The atomistic mechanisms are proposed for the origin of the static and the dynamic friction forces. The mechanism for the origin of the static friction force resembles the mechanical locking mechanism in a surface roughness model. The origin of the dynamic friction force is formulated as a problem of how the given translational kinetic energy dissipates into the internal relative motions of constituent atoms of bodies during sliding. From studying that the available phase space volume of the translational motion becomes negligible small for a large system size, compared with that of the internal motions, it is concluded that the energy dissipation occurs irreversibly from the translational motion to the internal motions. A phenomenon of superlubricity, where two solid bodies move relatively with no resistance, is discussed.

A Numerical Simulation of Interfacial Slip and its Role in Friction

2012 ◽  
Author(s):  
Jeffrey L. Streator
Keyword(s):  
Friction Coefficient ◽  
Friction Force ◽  
Lateral Displacement ◽  
Reaction Force ◽  
Static Friction ◽  
Constant Load ◽  
Interfacial Slip ◽  
Stick Slip ◽  
Elastic Slab ◽  
Static Coefficient Of Friction

The transition from static friction to kinetic friction results from the attainment of a point of instability, whereby interfacial slip becomes more energetically favorable than sticking. Such an instability is explored in this work via a plane-strain elastostatic analysis. A rigid pin of prescribed geometry is placed in contact with an elastic slab and translated horizontally under conditions of constant load. An intrinsic static coefficient of friction is prescribed, which limits the ratio of shear stress to contact pressure at each location within the interface. Additionally, the surface of the elastic slab is given a desired undulation to simulate the effects of surface roughness. As the pin is translated horizontally, a lateral reaction force (i.e., friction force) is developed and is observed to grow nearly linearly with increasing lateral displacement. At a critical point, a substantial portion of the interface experiences slip, leading to a large decrease in the friction force and thereby revealing a stick-slip behavior. It is found that the overall (macroscopic) static friction coefficient can be significantly less than the intrinsic friction coefficient and that the presence of even a small amount of roughness can have a large effect on the friction force.

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.

Robust Nonlinear Stick-Slip Friction Compensation

1991 ◽  
Vol 113 (4) ◽  
pp. 639-645 ◽  
Author(s):  
S. C. Southward ◽  
C. J. Radcliffe ◽  
C. R. MacCluer
Keyword(s):  
Friction Force ◽  
Direct Method ◽  
Piecewise Linear ◽  
Static Friction ◽  
Force Term ◽  
Stick Slip ◽  
Servo Systems ◽  
Stability And Control ◽  
Nonlinear Compensation ◽  
And Control

A nonlinear compensation force for stick-slip friction is developed to supplement a proportional + derivative control law applied to a one-degree-of-freedom mechanical system. Inertial control objects acted on by stick-slip friction are common mechanical components in mechanical servo systems and the conceptual model chosen for this investigation is a mass sliding on a rough surface. The choice of a discontinuous compensation force is motivated by the requirement that the desired reference be a unique equilibrium point of the system. The stick-slip friction force, modelled with a sticking force term and a slipping force term, generates discontinuous state derivatives. A Lyapunov function is introduced to prove global asymptotic stability of the desired reference using a modification of the direct method for discontinuous systems. Stability is verified numerically as well as experimentally. The nonlinear compensation force is robust with respect to the character of the slipping force which is assumed to lie within a piecewise linear band. Exact knowledge of the static friction force levels is not required, only upper bounds for these levels. Stability and control effectiveness is verified analytically, numerically and experimentally on a laboratory test stand.

scholarly journals Effect of Stick - Slip Phenomena between Human Skin and UHMW Polyethylene

2021 ◽  
Vol 29 (3) ◽  
Author(s):  
Emad Kamil Hussein ◽  
Kussay Ahmed Subhi ◽  
Tayser Sumer Gaaz
Keyword(s):  
Friction Coefficient ◽  
Human Skin ◽  
Coefficient Of Friction ◽  
Normal Load ◽  
Static Friction ◽  
Time Interval ◽  
Dynamic Friction ◽  
Sliding Velocity ◽  
Stick Slip ◽  
The Coefficient Of Friction

The present paper investigates experimentally effect of applied load and different velocity on the coefficient of friction between two interacting surfaces (human skin and Ultra-high-molecular-weight polyethylene (UHMW- polyethylene) at static and dynamic friction. It is possible to conclude specific point based on the above practical part and frictional analysis of this investigation as the most important mechanical phenomenon was creep has been observed a stick time interval where the static friction force is significantly increased during this stroke. The analytical model for stick-slip of skin and UHMWPE is proposed. The difference between static and kinetic friction defines the amplitude of stick-slip phenomena. The contact pressure, the sliding velocity, and rigidity of system determine the stability conditions of the movement between skin and UHMWPE. Experiments were carried out by developing a device (friction measurement). Variations of friction coefficient during the time at different normal load 4.6 and 9.2 N and low sliding velocity 4, 5, 6 and 7 mm/min were experimentally investigated. The results showed that the friction coefficient varied with the normal load and low sliding velocity. At static friction, the coefficient of friction decreased when the time increases, whereas, at dynamic friction, the coefficient of friction decreased when the time increased at normal load 4.6 and 9.2 N.

scholarly journals Adaptive Compensation of Friction Forces with Differential Filter

2008 ◽  
Vol 3 (1) ◽  
pp. 80 ◽  
Author(s):  
Kouichi Mitsunaga ◽  
Takami Matsuo
Keyword(s):  
Friction Force ◽  
Adaptive Controller ◽  
Friction Model ◽  
Dynamic Friction ◽  
Nonlinear Friction ◽  
Adaptive Compensation ◽  
Friction Forces ◽  
Fuzzy Adaptive Controller ◽  
Fuzzy Adaptive

In this paper, we design an adaptive controller to compensate the nonlinear friction model when the output is the position. First, we present an adaptive differential filter to estimate the velocity. Secondly, the dynamic friction force is compensated by a fuzzy adaptive controller with position measurements. Finally, a simulation result for the proposed controller is demonstrated.

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.

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