We present a new approach to modeling contact between rigid objects that augments an individual Coulomb friction point-contact model with rolling and spinning friction constraints. Starting from the intersection volume, we compute a contact normal from the volume gradient. We compute a contact position from the first moment of the intersection volume, and approximate the extent of the contact p...

In this paper, efficient algorithms for contact problems with Tresca and Coulomb friction in three dimensions are presented and analyzed. The numerical approximation is based on mortar methods for nonconforming meshes with dual Lagrange multipliers. Using a nonsmooth complementarity function for the 3D friction conditions, a primal-dual active set algorithm is derived. The method determines act...

This report presents a new way to model and identify single-link flexible arms when Coulomb friction is present in the joint. In order to isolate the effects of this nonlinearity, the arm model is divided into two submodels: motor and beam. The two anm coupled through the torque at the base of the beam. A systematic method is developed to obtain the dynamics of a lumped-mass flexible beam, and ...

In this paper, efficient algorithms for contact problems with Tresca and Coulomb friction in three dimensions are presented and analyzed. The numerical approximation is based on mortar methods for nonconforming meshes with dual Lagrange multipliers. Using a nonsmooth complementarity function for the three-dimensional friction conditions, a primal-dual active set algorithm is derived. The method...

Friction between ordered, atomically smooth surfaces at the nanoscale (nanofriction) is often governed by stick-slip processes. To test long-standing atomistic models of such processes, we implemented a synthetic nanofriction interface between a laser-cooled Coulomb crystal of individually addressable ions as the moving object and a periodic light-field potential as the substrate. We show that ...

A friction identification method in a frequency domain is proposed for a precision servomechanism. A nonlinear friction model including static, Coulomb, and viscous friction as well as Stribeck effect is considered in this paper. Friction models are formulated by using describing functions. Friction elements are estimated through the limit cycle analysis in a velocity control loop. A Butterwort...

This contribution presents a friction estimator for industrial purposes which identifies Coulomb friction in a steering system. The estimator only needs a few, usually known, steering system parameters. Friction occurs on almost every mechanical system and has a negative influence on high-precision position control. This is demonstrated on a steering angle controller for highly automated drivin...