Two distinct regimes are considered when it comes to friction: gross-sliding regime and presliding regime [1]. Friction in the gross-sliding regime contains familiar and classic concepts of static friction, Coulomb friction, and Stribeck curve. It is more intriguing, on the other hand, that friction in the pre-sliding regime behaves like a non-linear spring with hysteresis, significantly impact...

Friction modeling and identification is a prerequisite for the accurate control of electromechanical systems. This paper considers the identification and control of friction in a high load torque DC motor to the end of achieving accurate tracking. Model-based friction compensation in the feedforward part of the controller is considered. For this purpose, friction model structures ranging from t...

Two distinct regimes are considered when it comes to friction: gross-sliding regime and presliding regime [1]. Friction in the gross-sliding regime contains familiar and classic concepts of static friction, Coulomb friction, and Stribeck curve. It is more intriguing, on the other hand, that friction in the pre-sliding regime behaves like a non-linear spring with hysteresis, significantly impact...

Friction accounts for more than 60% of the motor torque, and hard nonlinearities due to Coulomb friction and stiction severely degrade control performances as they account for nearly 30% of the industrial robot motor torque. Although many friction compensation methods are available (Armstrong-Helouvry et al., 1994; Lischinsky et al., 1999; Bona & Indri, 2005;), here we only introduce relatively...

This paper considers the issue of modeling the pivot nonlinearity in a typical hard disk drive, taking into account viscous friction, Coulomb friction and hysteresis effects. It presents a nonlinear compensator design, based on a proposed model, to make the compensated system behave like a double integrator regardless of the magnitude of the input current. It describes extensive experiments, ca...

The paper deals with a discrete model of a two-dimensional Signorini problem with Coulomb friction and a coefficient of friction F depending on the spatial variable. It is shown that a solution exists for any F and is unique if F is sufficiently small. We also prove that this unique solution is a Lipschitz continuous function of F . Numerical realization is done by the piecewise smooth Newton m...

The purpose of this paper is to study the solutions to the Signorini problem with Coulomb friction (the so-called Coulomb problem). Some optimal a priori estimates are given and a uniqueness criterion is exhibited. Recently, nonuniqueness examples have been presented in the continuous framework. It is proven, here, that if a solutions satisfies a certain hypothesis on the tangential displacemen...

This paper discusses Coulomb failure criteria for brittle deformation of intact rock and fault gouge. Data are presented from laboratory experiments designed to identify the critical gouge layer thickness required to effect a transition from the standard Coulomb criterion to a modified failure law (referred to as Coulomb plasticity) appropriate for simple shear of a gouge layer. Experiments wer...

We propose a mean field (MF) theory for a homogeneously driven granular gas of inelastic particles with Coulomb friction. The model contains three parameters, a normal restitution coefficient rn, a maximum tangential restitution coefficient r m t , and a Coulomb friction coefficient μ. The parameters can be tuned to explore a wide range of physical situations. In particular, the model contains ...

This paper deals with the solution of the discretized quasistatic 3D Signorini problems with local Coulomb friction. After a time discretization we obtain a system of static contact problems with Coulomb friction. Each of these problems is decomposed by the TFETI domain decomposition method used in auxiliary contact problemswith Tresca friction. The algebraic formulation of these problems in 3D...