scholarly journals An Improvement Proposal to the Static Friction Model

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Sergio Sánchez-Mazuca ◽  
Ricardo Campa
Keyword(s):  
Large Scale ◽  
Static Friction ◽  
Control Area ◽  
Friction Model ◽  
Rate Of Change ◽  
Direct Drive ◽  
Mechatronic Systems ◽  
Proposed Model ◽  
Drive Motor ◽  
Friction Models

Friction is a force acting against the relative motion between two surfaces in contact. This phenomenon is present in all mechanical systems and has a great impact on the control area. The design of mechatronic systems and the compensation techniques require a broad knowledge of the effects that friction produces. The phenomenon has two well-defined phases: static friction presents before the motion between the surfaces in contact is clearly visible, while kinetic friction appears when that motion at large scale has already started. There are different friction models for each of those phases. In this work we propose an improvement to the static friction models, which consist in assuming that the maximum static friction coefficient is no more a constant but a function of the rate of change of the external force that produces the motion. After explaining and justifying the proposal, the procedure for obtaining the parameters of the new model is mentioned. At the end, an experimental study on a direct-drive motor allows us to validate the proposed model.

Static Friction in a Robot Joint—Modeling and Identification of Load and Temperature Effects

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
André Carvalho Bittencourt ◽  
Svante Gunnarsson
Keyword(s):  
Static Friction ◽  
Joint Modeling ◽  
Friction Model ◽  
Load Torque ◽  
Complex Interactions ◽  
Proposed Model ◽  
Friction Models ◽  
Interacting Surfaces ◽  
Sum Of Functions ◽  
Wide Operating

Friction is the result of complex interactions between contacting surfaces in down to a nanoscale perspective. Depending on the application, the different models available are more or less suitable. Static friction models are typically considered to be dependent only on relative speed of interacting surfaces. However, it is known that friction can be affected by other factors than speed. In this paper, the typical friction phenomena and models used in robotics are reviewed. It is shown how such models can be represented as a sum of functions of relevant states which are linear and nonlinear in the parameters, and how the identification method described in Ref. [1] can be used to identify them when all states are measured. The discussion follows with a detailed experimental study of friction in a robot joint under changes of joint angle, load torque, and temperature. Justified by their significance, load torque and temperature are included in an extended static friction model. The proposed model is validated in a wide operating range, considerably improving the prediction performance compared to a standard model.

scholarly journals A Static Friction Model for Unlubricated Contact of Random Rough Surfaces at Micro/Nano Scale

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 368
Author(s):  
Shengguang Zhu ◽  
Liyong Ni
Keyword(s):  
Rough Surfaces ◽  
Static Friction ◽  
Friction Model ◽  
Elastic Contact ◽  
Nano Scale ◽  
Random Rough Surfaces ◽  
Proposed Model ◽  
Dissipation Mechanism ◽  
Rigid Plane ◽  
Contact Situation

A novel static friction model for the unlubricated contact of random rough surfaces at micro/nano scale is presented. This model is based on the energy dissipation mechanism that states that changes in the potential of the surfaces in contact lead to friction. Furthermore, it employs the statistical theory of two nominally flat rough surfaces in contact, which assumes that the contact between the equivalent rough peaks and the rigid flat plane satisfies the condition of interfacial friction. Additionally, it proposes a statistical coefficient of positional correlation that represents the contact situation between the equivalent rough surface and the rigid plane. Finally, this model is compared with the static friction model established by Kogut and Etsion (KE model). The results of the proposed model agree well with those of the KE model in the fully elastic contact zone. For the calculation of dry static friction of rough surfaces in contact, previous models have mainly been based on classical contact mechanics; however, this model introduces the potential barrier theory and statistics to address this and provides a new way to calculate unlubricated friction for rough surfaces in contact.

A Regularized Contact Model for Multibody System Simulation

2016 ◽  
Author(s):  
Albert Peiret ◽  
Farnood Gholami ◽  
József Kövecses ◽  
Josep M. Font-Llagunes
Keyword(s):  
Multibody Systems ◽  
Large Scale ◽  
Multibody System ◽  
Linear Complementarity Problems ◽  
Friction Model ◽  
Computational Performance ◽  
Unilateral Contacts ◽  
Wheel Model ◽  
Friction Models ◽  
Coulomb Model

Simulation of large-scale multibody systems with unilateral contacts requires formulations with which good computational performance can be achieved. The availability of many solver algorithms for Linear Complementarity Problems (LCP) makes the LCP-based formulations a good candidate for this. However, considering friction in contacts asks for new friction models compatible with this kind of formulations. Here, a new, regularized friction model is presented to approximate the Coulomb model, which allows to formulate the multibody system dynamics as a LCP with bounds. Moreover, a bristle approach is used to approximate the stiction force, so that it improves the numerical behaviour of the system and makes it able to handle redundancy coming from the friction interfaces. Several examples using a 3D wheel model has been carried out, and the proposed friction model shows a better approximation of the Coulomb model compared to other LCP-based formulations.

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

2000 ◽  
Vol 214 (3) ◽  
pp. 173-184 ◽  
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.

Modeling and Control Design for a Wheeled Mobile Platform

2013 ◽  
Author(s):  
Byungchan Jung ◽  
Henryk Flashner ◽  
Jill McNitt-Gray
Keyword(s):  
Static Friction ◽  
Friction Model ◽  
Control Law ◽  
Modeling And Control ◽  
Lugre Friction Model ◽  
Backstepping Approach ◽  
Tracking Controllers ◽  
Friction Models ◽  
Lugre Friction ◽  
And Control

A model of a wheeled platform that includes slipping is formulated. Slipping is modeled by adopting the LuGre friction model. This is a dynamic friction model that can reproduce realistic friction phenomena not present in static friction models. Using the backstepping approach, tracking controllers for non-slipping and slipping cases are developed and compared via simulation. The proposed control law is designed to be robust with respect to the change in system parameters such as the platform’s mass and moment inertia. Simulation results show good performance for point stabilization in specific destination postures, as well as for tracking.

A new friction model for the slide guide in elevator systems: Experimental and theoretical investigations

2008 ◽  
Vol 222 (11) ◽  
pp. 2177-2189 ◽  
Author(s):  
X G Zhang ◽  
K J Guo ◽  
H G Li ◽  
G Meng
Keyword(s):  
Time Lag ◽  
Friction Model ◽  
Dynamical Analysis ◽  
Contact Friction ◽  
Proposed Model ◽  
Theoretical Investigations ◽  
Friction Models ◽  
Design And Manufacture ◽  
Sliding Regimes

In the design and manufacture of elevator systems, the slide guide in elevators moves in contact against the guide rail. This kind of surface contact exhibits a highly non-linear hysteretic friction behaviour, which hampers the riding quality of the elevator systems to a great extent. First, this paper presents an experimental investigation on this type of phenomenon through the measurement of contact friction force between the interface of the slide guide and the rail under different combinations of input parameters. The experiment clearly shows various types of frictional behaviour, including presliding/gross-sliding regimes, the transition behaviour between them, friction overshoot, time lag, velocity (weakening and strengthening) dependence, etc. In addition, it is found that for different materials in contact, lubrication conditions and friction duration have strong impacts on the evaluation of their friction characteristics. Based on the observations of this test, an improved friction model derived from the Bouc—Wen model is then proposed and compared with other friction models. The Bouc—Wen model is improved by adding elements considering the velocity dependence and friction overshoot. The numerical simulations show that the proposed model can capture the behaviour found in the experiments, agrees with the experimental data reasonably well, and may be used for the dynamical analysis of the elevator systems.

scholarly journals Study of Dynamics of Block-Media in the Framework of Minimalistic Numerical Models

2020 ◽  
pp. 143-168
Author(s):  
Alexander E. Filippov ◽  
Valentin L. Popov
Keyword(s):  
Numerical Models ◽  
Seismic Energy ◽  
Static Friction ◽  
Stability Diagram ◽  
Friction Model ◽  
Low Energy ◽  
Stick Slip ◽  
State Dependent ◽  
Proposed Model ◽  
Characteristic Features

AbstractOne of the principal methods of preventing large earthquakes is stimulation of a large series of small events. The result is a transfer of the rapid tectonic dynamics in a creep mode. In this chapter, we discuss possibilities for such a transfer in the framework of simplified models of a subduction zone. The proposed model describes well the basic characteristic features of geo-medium behavior, in particular, statistics of earthquakes (Gutenberg Richter and Omori laws). Its analysis shows that local relatively low-energy impacts can switch block dynamics from stick–slip to creep mode. Thus, it is possible to change the statistics of seismic energy release by means of a series of local, periodic, and relatively low energy impacts. This means a principal possibility of “suppressing” strong earthquakes. Additionally, a modified version of the Burridge-Knopoff model including a simple model for state dependent friction force is derived and studied. The friction model describes a velocity weakening of friction between moving blocks and an increase of static friction during stick periods. It provides a simplified but qualitatively correct stability diagram for the transition from smooth sliding to a stick–slip behavior as observed in various tribological systems. Attractor properties of the model dynamic equations were studied under a broad range of parameters for one- and two-dimensional systems.

Development of Sensor-Less Power-Assisted System with Disturbance Observer Considering High Friction

2013 ◽  
Vol 25 (6) ◽  
pp. 1020-1028
Author(s):  
Takanori Miyoshi ◽  
◽  
Ryosuke Imai ◽  
Kazuhiko Terashima ◽  
Kanemitsu Ochiai ◽  
...  
Keyword(s):  
High Power ◽  
Disturbance Observer ◽  
High Speed ◽  
Static Friction ◽  
Force Sensor ◽  
Direct Drive ◽  
Speed Reduction ◽  
Drive Motor ◽  
Support Device ◽  
Friction Parameters

Japan has a dwindling birthrate and a rapidly aging population, which has led to an increasing number of elderly laborers. Although this has spurred development into power-assisted (PA) equipment that can reduce the physical demands, most of power assisted systems developed so far have used the force sensor, a direct drive motor, or a high power motor. The PA machine using force sensor is unable to detect and avoid obstacles that might collide with nonsensor components of the machine. The direct drive motor is too expensive for the practical use and its power tends to increase. According to Japanese law, a high power motor is not allowed to cooperate together with laborers in the factory. Thus, in this research, a sensor-less power-assisted (PA) system capable of estimating operator force based on a disturbance observer and friction correction is designed and built for a high friction production support device using a lowcapacity servo motor and a high-speed reduction ratio reducer. First, a dynamic model of a production support device is identified with specific friction parameters. Next, a sensor-less PA system is constructed that is equipped with an appropriate disturbance observer and dynamic friction correction. Moreover, the static friction issues are solved by the regular driving command. Finally, the accuracies of estimated force are examined, and the effectiveness of the constructed sensor-less PA system is verified.

A New LuGre Friction Model for MR-9000 Type MR Damper

2008 ◽  
Author(s):  
Fan Yang ◽  
Ramin Sedaghati ◽  
Ebrahim Esmailzadeh
Keyword(s):  
Dynamic Behavior ◽  
Large Scale ◽  
Optimization Technique ◽  
Mr Damper ◽  
Least Square Method ◽  
Friction Model ◽  
Least Square ◽  
Lugre Friction Model ◽  
Proposed Model ◽  
Lugre Friction

This paper presents a new hysteresis model, based on the LuGre friction model, to analyze the dynamic behavior of large-scale Magneto-Rheological (MR) damper (MR-9000 type MR-damper [1]) accurately and efficiently. The gradient based optimization technique and the least square method will be utilized to identify the modal parameters. The dynamic behavior of MR-damper under different types of excitation and input current have been predicted using the proposed model and then compared with those predicted using modified Bouc-Wen model to verify the validity of the proposed model.

Model and Method for Contributor’s Quality Assessment in Community Image Tagging Systems

2018 ◽  
pp. 45-51
Author(s):  
A. V. Ponomarev
Keyword(s):  
Large Scale ◽  
Wide Spectrum ◽  
Preference Relation ◽  
Pairwise Comparison ◽  
Ground Truth ◽  
Comparison Method ◽  
Characteristic Matrix ◽  
Image Tagging ◽  
Proposed Model

Introduction: Large-scale human-computer systems involving people of various skills and motivation into the information processing process are currently used in a wide spectrum of applications. An acute problem in such systems is assessing the expected quality of each contributor; for example, in order to penalize incompetent or inaccurate ones and to promote diligent ones.Purpose: To develop a method of assessing the expected contributor’s quality in community tagging systems. This method should only use generally unreliable and incomplete information provided by contributors (with ground truth tags unknown).Results:A mathematical model is proposed for community image tagging (including the model of a contributor), along with a method of assessing the expected contributor’s quality. The method is based on comparing tag sets provided by different contributors for the same images, being a modification of pairwise comparison method with preference relation replaced by a special domination characteristic. Expected contributors’ quality is evaluated as a positive eigenvector of a pairwise domination characteristic matrix. Community tagging simulation has confirmed that the proposed method allows you to adequately estimate the expected quality of community tagging system contributors (provided that the contributors' behavior fits the proposed model).Practical relevance: The obtained results can be used in the development of systems based on coordinated efforts of community (primarily, community tagging systems). 

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