تحليل و كنترل لغزش در جابجايي اجسام در تماس با سطوح هموار توسط انگشتان نرم

چكيده انگليسي :

Slippage Analysis and Control in Manipulation of Objects in Contact with Even Surfaces Using Soft Fingers Amin Fakhari a fakhari@me iut ac ir December 17 2015 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree Doctor of Philosophy PhD Language FarsiSupervisor Mehdi Keshmiri Assoc Prof mehdik@cc iut ac ir AbstractUsing soft fingers increases stability and dexterity in object grasping and manipulation This is because of theenlargement of the contact interface between the soft fingers and the object Therefore a frictional momentalong with tangential frictional force and normal force is applied on the contact interface In this research softcontact modeling and also dynamic analysis and slippage control in object manipulation with the use of softfingers is studied Previous models for pressures distribution in the contact interface of a soft finger have beenproposed without considering the effect of the tangential forces which are usually exerted in the contact interfaceof a soft finger during grasping and manipulation Therefore a new and more accurate model is proposed todescribe the asymmetry of the pressure distribution in the contact interface of a hemispherical soft finger underthe existence of both normal and tangential forces This model is derived based upon observations from previousliterature According to the proposed model an improved and more accurate friction limit surface is presented Then the soft contact forces in object grasping are examined experimentally Although slippage phenomenonhas a crucial role in robust grasping and stable manipulation in the most of previous researches in the fieldof finger manipulation it is assumed that the slippage between finger and object does not occur Therefore at first general models of one dimensional and also planar slippage in soft contacts are proposed In thesemethods equality and inequality relations of different states of planar contact are rewritten in the form of a singlesecond order differential equation with variable coefficients These coefficients are determined on the basis ofthe slippage conditions The planar slippage model is derived based on the concept and features of ellipsoidapproximation of the friction limit surface These methods are used in dynamic analysis of manipulation of anobject using a planar two link soft finger and also a spatial three link soft finger on a horizontal surface Foreach case a controller is designed to reduce and remove the undesired slippage occurs between soft finger andobject and simultaneously to move the object on a predefined desired path The controllers designed for planartwo link soft finger are based on the rigid fingertip model using the concept of feedback linearization and alsosliding mode for each phase of the system dynamics and the controller designed for spatial three link soft fingeris similar to what human beings do when manipulating an object on a horizontal plane Numerical simulationsverify the acceptable performance of the controller in removing the undesired finger slippage and moving theobject on a predefined path despite of a slippage occurrence and also parametric and surface uncertainties Keywords1 Contact Modeling 2 Soft Finger 3 Grasping and Manipulation 4 Friction Limit Surface 5 SlippageControl

فخاري، امين

تحليل و كنترل لغزش در جابجايي اجسام در تماس با سطوح هموار توسط انگشتان نرم

مدل سازي تماس , گرفتن و جابجايي , سطح محدود اصطكاكي