This paper addresses the problem of obtaining models of nonlinear mechanisms for use in virtual prototyping systems. The objective of the described modeling procedure is to more accurately represent the feel of complex mechanisms in force feedback applications. The model structure selected for this study is a 2-order impedance model, with mass, damping, stiffness, and coulomb friction that vary...

In this paper, we study the problem of predicting the acceleration of a set of rigid, 3-dimensional bodies in contact with Coulomb friction. The nonlinearity of Coulomb's law leads to a nonlinear complementarity formulation of the system model. This model is used in conjunction with the theory of quasi-variational inequalities to prove for the rst time that multi-rigid-body systems with all con...

Analysis and estimation of friction and compensation for its effects in the control of an electrohydraulic manipulator is addressed in this paper. The specific hydraulic manipulator is an integral part of an automated fish processing machine which has been developed in our laboratory. The analysis reveals that considerable static and dynamic friction exists in the system. An available nonlinear...

The existence and (non-)uniqueness of rigid multibody problems with impact, contact and friction is discussed by means of the renowned Painlevé paradox. Different approaches to solve such contact problems, their pros and cons and their connections are discussed.

There have been many attempts to derive continuum models for dense granular flow, but a general theory is still lacking. Here, we start with Mohr-Coulomb plasticity for quasi-two-dimensional granular materials to calculate (average) stresses and slip planes, but we propose a "stochastic flow rule" (SFR) to replace the principle of coaxiality in classical plasticity. The SFR takes into account t...

Fluid-based locomotion at low Reynolds number is subject to the constraints of the scallop theorem, which dictate that body kinematics identical under a time-reversal symmetry (in particular, those with a single degree of freedom) cannot display locomotion on average. The implications of the theorem naturally compel one to ask whether similar symmetry constraints exist for locomotion in differe...

In general, joints are assumed without clearance in the dynamic analysis of multi-body echanical systems. When joint clearance is considered, the mechanism obtains two uncontrollable degrees of freedom and hence the dynamic response considerably changes. The joints’ clearances are the main sources of vibrations and noise due to the impact of the coupling parts in the joints. Therefore, the syst...

For two simple setups it is discussed, how dissipative grain-grain interactions give rise to unexpected properties on large scales. In the rst example, a spherical particle rolling along a rough surface experiences an eeective viscous friction on large time scales. It is due to temporal correlations among collisions with incomplete normal restitution. The second example is a sheared granular pa...