Direct methods for trajectory optimization are widely used for planning locally optimal trajectories of robotic systems. Most state-of-the-art techniques treat the discontinuous dynamics of contact as discrete modes and restrict the search for a complete path to a specified sequence through these modes. Here we present a novel method for trajectory planning through contact that eliminates the r...

The systematic errors due to the practical implementation of the contact dynamics method for simulation of dense granular media are examined. It is shown that, using the usual iterative solver to simulate a chain of rigid particles, effective elasticity and sound propagation with a finite velocity occur. The characteristics of these phenomena are investigated analytically and numerically in ord...

The most difficult aspect of rigid-body simulation is contact modeling. Two major subproblems of contact modeling are detecting contacts and computing contact forces. Although typically studied in isolation, these problems are tightly intertwined in simulation. This paper describes a method for fitting the pieces together. It gives an overview of the V-Clip collision detection algorithm, which ...

In this paper, the main goal is to present an experimental comparison of the two prevailing contact modeling approaches of the bipedal locomotion, i. e. rigid versus compliant contact model. To do this, first, an explicit dynamics model for the robot multibody with rigid model of contact for various phases of walking is developed. Then, in order to develop a model with compliant contact, a phys...

Motivated by applications in rigid body contact simulation we develop a numerically robust, randomized Quadratic Programming algorithm. We show that the resulting solver remains robust under highly constrained and redundant conditions, while also detecting infeasibility conditions. Its expected complexity is linear in the number constraints imposed and our experiments show that it performs well...

In this work, we study a unilateral contact problem with non local friction of Coulombbetween a locking material and a rigid foundation. In the first step , we present the mathematicalmodel for a static process, we establish the variational formulation in the form of a variationalinequality and we prove the existence and uniqueness of the solution. In the second step, usingthe penalty method we...

We studied the wearing of hard gas permeable contact lenses during decompression in a hyperbaric environment. Twenty-four exposures of three different lens materials were carried out in a hyperbaric chamber. The dry air dive profiles were: 45.72 m (150 ft) for 30 min and 15 min; 22.86 m (75 ft) for 15 min; and 11.43 m (37.5 ft) for 15 min. Bubbles occurred under all lens types; they were seen a...

In part I of this work, we study adhesionless contact of a long rectangular elastic membrane with a rigid substrate. Our model is based on finite strain theory and is valid for arbitrarily large deformations. Both frictionless and no-slip contact conditions are considered. Exact closed form solutions are obtained for frictionless contact. For small contact, the differences between these two con...