Modeling of Piezo-Actuated Stick-Slip Micro-Drives: An Overview

This paper gives an overview about problems of modeling of piezo-actuated stick-slip micro-drives. It has been found that existing prototypes of such devices have been investigated empirically. There is only few research dealing with the theory behind this kind of drives. By analyzing the current research activities in this field, it is believed that the model of the drive depends strongly on the friction models, but in most cases neglecting any influences of the guilding system.These analyses are of fundamental importance for an integrated model combining friction model and mechanical model offering promising possibilities for future research.

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Friction compensation control of an electropneumatic servovalve by using an evolutionary algorithm

Proceedings of the Institution of Mechanical Engineers Part I Journal of Systems and Control Engineering ◽

10.1243/0959651001540546 ◽

2000 ◽

Vol 214 (3) ◽

pp. 173-184 ◽

Cited By ~ 4

Author(s):

S H Choi ◽

C O Lee ◽

H S Cho

Keyword(s):

Search Algorithm ◽

Static Friction ◽

Open Loop ◽

Friction Model ◽

Experimental Results ◽

Friction Compensation ◽

Stick Slip ◽

Air Contamination ◽

Compensation Control ◽

Friction Models

A poppet-type electropneumatic servovalve developed in this study utilizes a poppet directly operated by a moving-coil actuator in the metering stage and is controlled by a digital controller. This servovalve is insensitive to air contamination and has no problem of air leakage at null, but it has relatively large friction between the O-rings installed in the peripheral grooves of the balance pistons and the valve sleeve. For friction compensation control, a static friction model that enables simulation of the stick-slip phenomena and a dynamic model that captures the friction behaviour such as presliding displacement and varying break-away force are presented. The parameters for the friction models are identified by utilizing an evolution strategy, one of the evolutionary algorithms, which is a probabilistic global search algorithm based on the model of natural evolution. These friction models are then used in designing a non-linear friction compensation controller. It is found in the experiment that the electropneumatic servovalve has almost no hysteresis and that the friction compensation control significantly improves valve performance. The experimental results of the open loop test on poppet positioning agree well with simulation results of the valve model with identified friction parameters. It is also shown that the experimental results of friction compensation control using a static friction model show a small steady state error but those using a dynamic friction model show almost no such error.

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A Nonlinear Friction Model for an Electromechanical Actuator Valve

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.799-800.1096 ◽

2015 ◽

Vol 799-800 ◽

pp. 1096-1101

Author(s):

Zsolt Horváth

Keyword(s):

Fault Detection ◽

Linear Model ◽

Friction Model ◽

Experimental Results ◽

Experimental Setup ◽

Nonlinear Friction ◽

Stick Slip ◽

Stribeck Effect ◽

Throttle Valve ◽

Friction Models

In this work we have extended a basic linear model of the Electromechanical Throttle Valve to a nonlinear friction model, which captures the most important friction phenomenon of interest for fault detection. In our examination we have implemented the Tustin’s friction model. This nonlinear friction model has only 4 parameters but describes the friction phenomenon of the Stribeck effect also it includes both the Stick and Slip regimes. To the validation of the actuator model and examination of the friction models we have performed experiments using the experimental setup of NI LabVIEW CompactRIO. The friction phenomenon as hysteresis, stick-slip and Stribeck effects, are an interest for fault detection of the Actuator Valve. The experimental results have shown, that Tustin’s model provides a good approach for modeling of the friction behaviour of the Electromechanical Throttle Valve.

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Experimental comparison of five friction models on the same test-bed of the micro stick-slip motion system

Mechanical Sciences ◽

10.5194/ms-6-15-2015 ◽

2015 ◽

Vol 6 (1) ◽

pp. 15-28 ◽

Cited By ~ 68

Author(s):

Y. F. Liu ◽

J. Li ◽

Z. M. Zhang ◽

X. H. Hu ◽

W. J. Zhang

Keyword(s):

Friction Model ◽

Test Bed ◽

Lugre Model ◽

Stick Slip ◽

Motion System ◽

Friction Models ◽

Micro Motion ◽

Coulomb Friction Model ◽

Stick Slip Motion ◽

Slip Motion

Abstract. The micro stick-slip motion systems, such as piezoelectric stick-slip actuators (PE-SSAs), can provide high resolution motions yet with a long motion range. In these systems, friction force plays an active role. Although numerous friction models have been developed for the control of micro motion systems, behaviors of these models in micro stick-slip motion systems are not well understood. This study (1) gives a survey of the basic friction models and (2) tests and compares 5 friction models in the literature, including Coulomb friction model, Stribeck friction model, Dahl model, LuGre model, and the elastoplastic friction model on the same test-bed (i.e. the PE-SSA system). The experiments and simulations were done and the reasons for the difference in the performance of these models were investigated. The study concluded that for the micro stick-slip motion system, (1) Stribeck model, Dahl model and LuGre model all work, but LuGre model has the best accuracy and (2) Coulomb friction model and the elastoplastic model does not work. The study provides contributions to motion control systems with friction, especially for micro stick-slip or step motion systems as well as general micro-motion systems.

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Improved Dynamic Friction Models for Simulation of One-Dimensional and Two-Dimensional Stick-Slip Motion

Journal of Tribology ◽

10.1115/1.1331057 ◽

2000 ◽

Vol 123 (4) ◽

pp. 661-669 ◽

Cited By ~ 35

Author(s):

Fitsum A. Tariku ◽

Robert J. Rogers

Keyword(s):

Mechanical Systems ◽

Friction Model ◽

Contact Forces ◽

Force Balance ◽

Two Dimensional ◽

Lumped Mass ◽

Stick Slip ◽

Normal Contact ◽

One Dimensional ◽

Friction Models

In many mechanical systems, the tendency of sliding components to intermittently stick and slip leads to undesirable performance, vibration, and control behaviors. Computer simulations of mechanical systems with friction are difficult because of the strongly nonlinear behavior of the friction force near zero sliding velocity. In this paper, two improved friction models are proposed. One model is based on the force-balance method and the other model uses a spring-damper during sticking. The models are tested on hundreds of lumped mass-spring-damper systems with time-varying excitation and normal contact forces for both one-dimensional and two-dimensional stick-slip motions on a planar surface. Piece-wise continuous analytical solutions are compared with solutions using other published force-balance and spring-damper friction models. A method has been developed to set the size of the velocity window for Karnopp’s friction model. The extensive test results show that the new force-balance algorithm gives much lower sticking velocity errors compared to the original method and that the new spring-damper algorithm exhibits no spikes at the beginning of sticking. Weibull distributions of the sticking velocity errors enable maximum errors to be estimated a priori.

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SME’s Performance Through Comparative Performance Indicators, Measured by Business Statistics- Albania Case

European Journal of Economics and Business Studies ◽

10.26417/ejes.v9i1.p361-370 ◽

2017 ◽

Vol 9 (1) ◽

pp. 361

Author(s):

Godiva Rembeci

Keyword(s):

Economic Performance ◽

National Economy ◽

Performance Indicators ◽

Future Research ◽

Productivity Measurement ◽

Comparative Performance ◽

Global Consensus ◽

Research Activities ◽

Business Statistics ◽

National Economies

Now days there is a global consensus among all stakeholders that SMEs represent a driving force to the overall economic development, due to their significant contribution both on GDP and employment of national economies. SMEs also by numbers dominate the world business stage, although their contribution does vary among the countries. SMEs in Albania represents about 98% of the total enterprises with a contribution to national GDP for about 70%. The structure and the performance of national economy is depended very much on the economic performance and contribution of SME, that’s why most of the governments have strategic programmes which support the SME’s development. To measure SMEs’ performance and their ability to compete on national and international markets requires a lot of information in all aspects. Through this paper the author aims to measure and analyze the economic performance of SMEs operating in Albania. To achieve this objective, official data on business statistics published by national the statistical office (INSTAT) are used for two years period 2014-2015. In addition using an international framework addressed to the objective “improve the techniques for SMEs productivity measurement”, for the first time, a set of comparative performance indicators is established and in doing so, those results can be used as term of reference in future research activities in SMEs sector. From the results it came out that although the positive growth rate of GDP during the last years , the performance indicators of SMEs show a slightly negative trend, indicating indirectly the need for support, in order to empower their contribution in national economy.

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Local Anesthetics and Recurrence after Cancer Surgery-What’s New? A Narrative Review

Journal of Clinical Medicine ◽

10.3390/jcm10040719 ◽

2021 ◽

Vol 10 (4) ◽

pp. 719

Author(s):

Sarah D. Müller ◽

Jonathan S. H. Ziegler ◽

Tobias Piegeler

Keyword(s):

Tumor Cells ◽

Circulating Tumor Cells ◽

Local Anesthetics ◽

Experimental Studies ◽

Perioperative Period ◽

Cancer Surgery ◽

Narrative Review ◽

Future Research ◽

Inflammatory Stress ◽

Research Activities

The perioperative use of regional anesthesia and local anesthetics is part of almost every anesthesiologist’s daily clinical practice. Retrospective analyses and results from experimental studies pointed towards a potential beneficial effect of the local anesthetics regarding outcome—i.e., overall and/or recurrence-free survival—in patients undergoing cancer surgery. The perioperative period, where the anesthesiologist is responsible for the patients, might be crucial for the further course of the disease, as circulating tumor cells (shed from the primary tumor into the patient’s bloodstream) might form new micro-metastases independent of complete tumor removal. Due to their strong anti-inflammatory properties, local anesthetics might have a certain impact on these circulating tumor cells, either via direct or indirect measures, for example via blunting the inflammatory stress response as induced by the surgical stimulus. This narrative review highlights the foundation of these principles, features recent experimental and clinical data and provides an outlook regarding current and potential future research activities.

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On the influence of delamination on laminated paperboard creasing and folding

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2011.0408 ◽

2012 ◽

Vol 370 (1965) ◽

pp. 1912-1924 ◽

Cited By ~ 17

Author(s):

Lars A. A. Beex ◽

Ron H. J. Peerlings

Keyword(s):

Cohesive Zone ◽

Mechanical Model ◽

Cohesive Zone Model ◽

Packaging Material ◽

Friction Model ◽

Zone Model ◽

General Mechanics ◽

Single Fold ◽

Wide Range

Laminated paperboard is used as a packaging material for a wide range of products. During production of the packaging, the fold lines are first defined in a so-called creasing (or scoring) operation in order to obtain uncracked folds. During creasing as well as folding, cracking of the board is to be avoided. A mechanical model for a single fold line has been proposed in a previous study (Beex & Peerlings 2009 Int. J. Solids Struct. 46 , 4192–4207) to investigate the general mechanics of creasing and folding, as well as which precise mechanisms trigger the breaking of the top layer. In the present study, we employ this modelling to study the influence of delamination on creasing and folding. The results reveal the separate role of the cohesive zone model and the friction model in the description of delamination. They also show how the amount of delamination behaviour should be controlled to obtain the desired high folding stiffness without breaking of the top layer.

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An Integrated Model for Demand‐Output Management in Service Organisations: Implications for Future Research

International Journal of Operations & Production Management ◽

10.1108/01443579110139660 ◽

1991 ◽

Vol 11 (1) ◽

pp. 51-67 ◽

Cited By ~ 5

Author(s):

Michael J. Showalter ◽

J. Dennis White

Keyword(s):

Integrated Model ◽

Future Research

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Digital competences of the workforce – a research topic?

Business Process Management Journal ◽

10.1108/bpmj-06-2016-0126 ◽

2017 ◽

Vol 23 (3) ◽

pp. 721-734 ◽

Cited By ~ 21

Author(s):

Matthias Murawski ◽

Markus Bick

Keyword(s):

Research Topic ◽

Future Research ◽

Digital Competence ◽

Content Type ◽

Research Activities ◽

Starting Point ◽

Pros And Cons ◽

Definition Of ◽

The Individual ◽

Practical Implications

Purpose Considering working in the digital age, questions on the consequences for the individual workers are, so far, often neglected. The purpose of this paper is to deal with the question of whether the digital competences of the workforce is a research topic. The authors argue for the thesis that it is indeed a research topic. Design/methodology/approach In addition to a literature analysis of the top IS, HR, and learning publications, non-scientific sources, as well as the opinions of the authors, are included. The authors’ thesis is challenged through a debate of corresponding pros and cons. Findings The definition of digital competences lacks scientific depth. Focussing on the workforce is valid, as a “lifelong” perspective is not mandatory for research. Digital competence research is a multidisciplinary task to which the IS field can make a valuable contribution. Research limitations/implications Although relevant references are included, some aspects are mainly driven by the opinions of the authors. The theoretical implications encompass a call for a scientific definition of digital competences. Furthermore, scholars should focus on the competences of the workforce, including occupations, roles, or industries. The authors conclude by providing a first proposal of a research agenda. Practical implications The practical implications include the alignment of multiple stakeholders for the design of “digital” curricula and the integration by HR departments of the construct of digital competences, e.g. for compensation matters and job requirements. Originality/value This paper is one of very few contributions in the area of the digital competences of the workforce, and it presents a starting point for future research activities.

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