Occupation and local times for skew Brownian motion with applications to dispersion across an interface

Advective skew dispersion is a natural Markov process defined ned by a di ffusion with drift across an interface of jump discontinuity in a piecewise constant diff usion coeffcient. In the absence of drift this process may be represented as a function of -skew Brownian motion for a uniquely determined value of = ; see Ramirez, Thomann, Waymire, Haggerty and Wood (2006). In the present paper the analysis is extended to the case of non-zero drift. A determination of the (joint) distributions of key functionals of standard skew Brownian motion together with some associated probabilistic semigroup and local time theory is given for these purposes. An application to the dispersion of a solute concentration across an interface is provided that explains certain symmetries and asymmetries in recently reported laboratory experiments conducted at Lawrence-Livermore Berkeley Labs by Berkowitz, Cortis, Dror and Scher (2009).Keywords: stochastic order, occupation time, Skew Brownian motion, local time, first passage time, advection-diffusion, elastic skew Brownian motionKeywords: stochastic order, occupation time, Skew Brownian motion, local time, first passage time, advection-diffusion, elastic skew Brownian motio

Friction-based slip detection in robotic grasping

A functional prototype of a friction-based object slippage detection gripper for robotic grasping and manipulation has been designed and built. Object grasping and manipulation experiments have been successfully performed to study the appropriateness of the methodology and the newly built slippage detection gripper. The main advantage of this slippage detection method is that slippage detection is an inherent capability of the sensing element, and not a derived capability like that of sensors based on vibration. This slippage detection and control strategy is simple by design and low in cost, but robust in function. It has the potential to be used in a variety of environments such as high temperatures, low temperatures and underwater. The robustness of the design makes it highly suitable for grasping and manipulating safely a large range of object weights and sizes.4 page(s

Optimal sensing requirement for slippage prevention in robotic grasping

This paper presents a new theoretical development and modelling related to the requirement of the minimum number of sensors necessary for slippage prevention in robotic grasping. A fundamental experimental investigation has been conducted to support the newly developed postulate. A series of basic experiments proved that it is possible to evaluate the contributions of various sensors to slippage prevention and control in robotic grasping. The use of three discrete physical sensors, one for each of the three sensing functions (normal, tangential and slippage), has been proven to be the most reliable combination for slippage prevention in robotic grasping. It was also proven that the best performance from a two-sensor combination can be achieved when normal grasp force and tangential force are both monitored in the grasping process

Optimum grasp force and resistance to slippage

This paper presents an analysis and experimental results as part of the research into the optimal rate of grasp force application in precision grasping. It also offers the concept of resistance to object rotation in the robot gripper, which in turn contributes to the resistance to object slippage during robotic object manipulation. It is envisaged that this knowledge will be useful to researchers and designers of robotic grippers, especially those for industrial applications

Optimal sensing requirement for slippage prevention in robotic grasping

This paper presents a new theoretical development and modelling related to the requirement of the minimum number of sensors necessary for slippage prevention in robotic grasping. A fundamental experimental investigation has been conducted to support the newly developed postulate. A series of basic experiments proved that it is possible to evaluate the contributions of various sensors to slippage prevention and control in robotic grasping. The use of three discrete physical sensors, one for each of the three sensing functions (normal, tangential and slippage), has been proven to be the most reliable combination for slippage prevention in robotic grasping. It was also proven that the best performance from a two-sensor combination can be achieved when normal grasp force and tangential force are both monitored in the grasping process