In this paper, we report on the design of a model-based controller that can achieve dynamical self-righting of a hexapod robot. Extending on our earlier work in this domain, we introduce a tractable multi-point contact model with Coulomb friction. We contrast the singularities inherent to the new model with other available methods and show that for our specific application, it yields dynamics w...

A new contact bond model based on the Mohr-Coulomb failure criterion has been implemented in PFC2D to reproduce the behaviour of frictional cohesive (c, φ) geomaterials. According to this model, the bond strength can be clearly divided into two distinct micromechanical contributions: an intergranular friction angle and a cohesive bond force. A parametric analysis has been run to validate the pr...

This article describes the detailed friction modeling of the Genera1 Electric GP132 industrial robot. Friction is an area whose importance is often discounted in the development of control systems because it is thought to be insignificant or unmodelable. This work demonstrates that friction does have a predictable structure, and that significant performance improvement can be realized through i...

Practical problems like regulating robot grippers critically rely on accurately predicted friction forces. Qualified methods are derived and discussed subsequently. Special attention is paid to the question of solution existence. A time-stepping scheme which supports Coulomb friction and inelastic impacts is implemented and the numerical results are analyzed. The approach proofs to be stable, a...

The goal is to analyze the semi-smooth Newton method applied to the solution of contact problems with friction in two space dimensions. The primal-dual algorithm for problems with the Tresca friction law is reformulated by eliminating primal variables. The resulting dual algorithm uses the conjugate gradient method for inexact solving of inner linear systems. The globally convergent algorithm b...

The oblique collisions between two axisymmetric disks moving on a flat horizontal surface are described in terms of impact modeling based the assumption that normal and tangential restitution mechanisms operate independently friction. Describing these usual Coulomb formulation, model allows for an interpretation some “anomalous” experimental data reported literature. These data, corresponding t...

The paper deals with shape optimization of dynamic contact problem with Coulomb friction for viscoelastic bodies. The mass nonpenetrability condition is formulated in velocities. The friction coefficient is assumed to be bounded. Using material derivative method as well as the results concerning the regularity of solution to dynamic variational inequality the directional derivative of the cost ...

For motion planning it is important to have an accu rate dynamic system model and in many cases friction is an important component of the model It is known however that when Coulomb friction is added to the rigid body dynamic equations the forward dynamic solution may not exist and if it exists it is not necessarily unique In this paper we study the existence and uniqueness prop erties of the f...

Modeling and identification of mechanical systems constitute an essential stage in practical control design and applications. Controllers commanding systems that operate at varying conditions or require high precision operation raise the need for a nonlinear approach in modeling and identification. Most mechanical systems used in industry are composed of masses moving under the action of positi...