This paper describes friction compensation based control of an industrial pneumatic actuator used for the variable geometry turbocharger (VGT). Adaptive LuGre model for friction has been used in this work. Friction force that is responsible for hysteresis and hunting phenomenon in the position control is compensated with two different control strategies designed to improve low velocity position...

The main objective of this paper is to propose a new friction compensation mechanism applied to robotic actuators. Friction is a phenomenon that changes with time and with actuator’s operational conditions. To deal with these parameters variations, it is proposed a neuro-fuzzy algorithm for friction identification and compensation. A Neural Network (NN) was trained off line. The NN output (comp...

In analogy with the standard macroscopic friction, here we present a comparative study of the friction force felt by moving vortices in superconductors and charge density waves. Using experiments and a model for this data, our observations (1) provide a link between friction at the micro- and macroscopic scales, (2) explain the roundness of the static-kinetic friction transition in terms of the...

in order to provide the data needed for the design of saffron processing equipment, physical properties of its flower were investigated. these properties included dimensions, mass, true and bulk densities, porosity, static and dynamic coefficients of friction, and terminal velocity as a function of moisture content. the average range of these properties for the three different parts of saff...

This paper gives a review on the applications of artificial neural network in friction stir welding. Friction stir welding is a fairly new solid state joining process and has found numerous applications including in aerospace, marine, automotive, railway and many more. Artificial neural network (ANN) is a valued research area. Study has been done on mechanical properties of weldements. Keywords...

A micromechanical study is made of the relationship between interparticle friction coefficient and macroscopic continuum friction and dissipation in idealised granular materials, using Discrete Element Method simulations with varying . As expected, macroscopic friction and dilatancy increase with . Surprisingly, dissipation is present even when or when . Hence, dissipation in idealised granular...

We study the van der Waals friction between two flat metal surfaces in relative motion. For good conductors, we find that normal relative motion gives a much larger friction than for parallel relative motion. The friction may increase by many orders of magnitude when the surfaces are covered by adsorbates, or can support low-frequency surface plasmons. In this case, the friction is determined b...

The classical problem of rebound is usually treated by assuming that the colliding bodies are rigid and that the coefficient of friction, ~ , is constant. Two contact states can be distinguished: slidinq, in which the ratio of friction force to normal force is equal to ~ , and rolling, in which the friction force is zero. If sliding gives way to rolling during impact, the friction force will fa...

The hydrodynamic friction used in many comparisons of isomerization reactions with Kramers’ theory is shown to be related to the translational friction. The fractional viscosity dependence of the translational friction of naphthalene is shown to account for the failure of hydrodynamic models for 1,l ‘-binaphthyl in alkanes. The success of the reorkntational model of friction is also discussed. ...

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...