This article presents computationally efficient algorithms for modeling two special cases of rigid contact— contact with only viscous friction and contact without slip—that have particularly useful applications in robotic locomotion and grasping. Modeling rigid contact with Coulomb friction generally exhibits O(n) expected time complexity in the number of contact points and 2 worst-case complex...

We show that the static friction force which must be overcome to render a sticking contact sliding is reduced if an external torque is also exerted. As a test system we study a planar disk lying on a horizontal flat surface. We perform experiments and compare with analytical results to find that the coupling between static friction force and torque is nontrivial: It is not determined by the Cou...

We study the effects of vertical vibrations on non-wetting large water sessile drops flattened by gravity. The solid substrate is characterized by a finite contact angle hysteresis (10-15 degrees). By varying the frequency and the amplitude of the vertical displacement, we observe two types of oscillations. At low amplitude, the contact line remains pinned and the drop presents eigen modes at d...

IT is a matter of experience that certain persons adjust well to contact lenses while others do not, despite perfect fitting. This adjustment is greatly facilitated if the sensitivity of the cornea is decreased, as it is after cataract extraction. One is therefore tempted to consider corneal sensitivity as a determining factor for the success of a fitting. Previous investigation of the subject ...

The field of tribology defined in Webster’s Dictionary as “a science that deals with the design, friction, wear and lubrication of interacting surfaces in relative motion” has a long and important history in science and technology[1]. The ancient Egyptians, for example, used water to lubricate the path of sleds employed to transport extremely heavy objects. The first scientific studies of frict...

The field of tribology defined in Webster’s Dictionary as “a science that deals with the design, friction, wear and lubrication of interacting surfaces in relative motion” has a long and important history in science and technology[1]. The ancient Egyptians, for example, used water to lubricate the path of sleds employed to transport extremely heavy objects. The first scientific studies of frict...

The sliding interfaces found in the body— within the eyes, the digestive system, and the articulating joints, for example—are soft and permeable yet extremely robust, possessing low friction. The common elements among these systems are hydrophilic biopolymer networks that provide physical surfaces, elasticity, and fluid permeability. Stiff, impermeable probes are traditionally used to assess th...

AIM This study evaluated the behavior of oral epithelial cells in contact with orthodontic appliances. METHODS Oral epithelial cells of clinically normal buccal mucosa were obtained by liquid-based exfoliative cytology from 22 orthodontic patients. The following regions were evaluated: a) oral mucosa exposed to friction from orthodontic brackets; b) oral mucosa exposed to friction from the tu...

Tribology-the science of friction, wear and lubrication-is of great importance for all technical applications where moving bodies are in contact. Nonetheless, little progress has been made in finding an exact atomistic description of friction since Amontons proposed his empirical macroscopic laws over three centuries ago. The advent of new experimental tools such as the friction force microscop...

We present a new method of neural friction compensa tion in manipulator control especially during dynamic tasks with de ned contact to external environment Such manipulator movements involve internal joint friction and external friction between tool and environment The suggested method compensates friction caused dis turbances by means of neural networks Based on a minimal friction model Lyapun...