Frictional Compliant Haptic Contact and Deformation of Soft Objects

Naci Zafer,Sezcan Yilmaz

doi:10.5772/63937

Abstract

This paper is concerned with compliant haptic contact and deformation of soft objects. A human soft fingertip model is considered to act as the haptic interface and is brought into contact with and deforms a discrete surface. A nonlinear constitutive law is developed in predicting normal forces and, for the haptic display of surface texture, motions along the surface are also resisted at various rates by accounting for dynamic Lund-Grenoble (LuGre) frictional forces. For the soft fingertip to apply forces over an area larger than a point, normal and frictional forces are distributed around the soft fingertip contact location on the deforming surface. The distribution is realized based on a kernel smoothing function and by a nonlinear spring-damper net around the contact point. Experiments conducted demonstrate the accuracy and effectiveness of our approach in real-time haptic rendering of a kidney surface. The resistive (interaction) forces are applied at the user fingertip bone edge. A 3-DoF parallel robotic manipulator equipped with a constraint based controller is used for the implementation. By rendering forces both in lateral and normal directions, the designed haptic interface system allows the user to realistically feel both the geometrical and mechanical (nonlinear) properties of the deforming kidney.

Highlights

Researchers have long been interested in the fundamental dynamic properties of contact interaction with deformableIn haptic rendering of deformable objects, constraint- and penalty-based methods have long been the interest of many researchers
Realizing that most tissue interaction research makes use of simple objects and kinaesthetic feedback, this study aims for haptic interaction modelling between a soft fingertip and a complex shaped nonlinearly viscoelastic object
In this paper we propose and demonstrate the use of a softfingertip model in interactive haptic rendering of deform‐ able surfaces

Summary

Introduction

Researchers have long been interested in the fundamental dynamic properties of contact interaction with deformable. In haptic rendering of deformable objects, constraint- and penalty-based methods have long been the interest of many researchers. Much has been accomplished over the last couple of decades in terms of the direct force and/or tactile feedback controllers [9, 10], realistic and fast haptic rendering of deformable objects has not yet been a success. The main obstacle to this endeavour is the diffi‐ culty in designing a unique and complete constitutive (load-deflection) model for nonlinear dynamic contact and deformations. Researchers have been interested in developing finite deformation models of various materials exhibiting nonlinear constitutive responses [11,12,13,14]. Research towards a complete accurate haptic contact and deformation system is still in development

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