Haptic Interaction with Deformable Objects

Modelling VR Systems for Textiles

verfasst von: Guido Böttcher

Verlag: Springer London

Buchreihe : Springer Series on Touch and Haptic Systems

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik" , Springer Professional "Wirtschaft"

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Über dieses Buch

The focus from most Virtual Reality (VR) systems lies mainly on the visual immersion of the user. But the emphasis only on the visual perception is insufficient for some applications as the user is limited in his interactions within the VR. Therefore the textbook presents the principles and theoretical background to develop a VR system that is able to create a link between physical simulations and haptic rendering which requires update rates of 1\,kHz for the force feedback. Special attention is given to the modeling and computation of contact forces in a two-finger grasp of textiles. Addressing further the perception of small scale surface properties like roughness, novel algorithms are presented that are not only able to consider the highly dynamic behaviour of textiles but also capable of computing the small forces needed for the tactile rendering at the contact point. Final analysis of the entire VR system is being made showing the problems and the solutions found in the work

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract

In the past decades computer graphics has become an essential part in science as it provides algorithms and methods helping to visualise problems and processes in different fields of research. For example, in weather forecasts, models are used to simulate the dynamics of the atmosphere and its interaction with seas and land masses. Without an adequate visualisation of the huge data sets produced by the models, it is very hard to make a forecast relying on the computed data.

Guido Böttcher

Chapter 2. Physical Simulation

Abstract

Without the understanding of the laws behind the physical behaviour of objects by means of interaction, a realistic simulation within a virtual environment cannot be achieved. The fundamental principles of the subject rely on the theories of classical and continuum mechanics. Therefore, in the following a review the physics governing the motion and deformation of bodies is given. The notations of the physical properties are based on Goldstein et al. (Classical Mechanics, Addison-Wesley, Reading, 2002), Reddy (Energy Principles and Variational Methods in Applied Mechanics, Wiley, New York, 2002) and Reddy (An Introduction to the Finite Element Method, McGraw-Hill, New York, 2006) which also give a good introduction, but have broader perspective in the concepts of classical mechanics.

Guido Böttcher

Chapter 3. Haptic Interaction

Abstract

Virtual Reality (VR) systems have evolved in the way that the visual immersion provided by technologies like CAVEs (Cruz-Neira et al. in Commun. ACM, 1992) or head mounted devices is nearly perfect. But since the visual quality reached a satisfactory level, a deficiency became apparent in the interaction with the virtual environment. The absence of touch information during manipulative task made interactions difficult and cumbersome. Moreover, the estimation of material characteristics where necessary, e.g. medical surgery simulation, is nearly impossible (cf. Robles-De-La-Torre in IEEE Multimed. 13(3):24, 2006). Therefore, VR systems requiring the user to make complex interactions are augmented by a touch feedback. In the following the issues and concepts in providing a touch feedback which is also known as haptic interaction will be explained.

Guido Böttcher

Chapter 4. VR System Framework

Abstract

This chapter presents the overall VR system and its functional blocks with their interaction. The VR system itself consist of visual, haptic and tactile renderers which display a scene, calculated by a physical model and modified by the user through haptic devices. The primary configuration of the system uses the GRAB device as haptic device. As it features in the modified version a tactile array at each end effector to stimulate the tip of thumb and index finger, the device is also used for tactile output.

Guido Böttcher

Chapter 5. Analysis of the VR System

Abstract

Managing the physical simulation of textiles with haptic contact interaction for two force-feedback devices required to exploit multi-core processor architectures. But for an optimal benefit of those architectures it was required to separate the system into partly independent processes to run on separate cores. Although the simulation and the contact rendering is tightly coupled, a separation of the two functional parts was being made. By splitting the textile simulation into two simulation threads having their own geometry, it was possible to run the parts on individual processing units. These two threads responsible for their corresponding area of influence namely the global textile and the local contact, had to be synchronised as the local thread is running on a much higher rate than the other due to force-feedback rendering. Moreover, the geometry of the local simulation is only handling a small fraction of the textile thus being an incomplete physical model. The dynamic change of the local geometry imposed also timing problems difficult to handle as the computation time varies. In both threads the additional flexibility of the numerical computations utilising completely the power of the processor cores affected the timing as well.

Guido Böttcher

Chapter 6. Summary & Outlook

Abstract

This work presented the theoretical background and the methods used in continuum mechanics and computational contact mechanics to describe the interaction of deformable bodies. With Signorini’s problem a most versatile approach to contact handling has been presented. Unfortunately, the computations required to solve the contact problem with this approach is currently not possible in haptic rendering. Therefore, a simpler model was suggested in the work at hand satisfying the tight time constraints of haptics.

Guido Böttcher

Backmatter

Titel: Haptic Interaction with Deformable Objects
verfasst von: Guido Böttcher
Verlag: Springer London
Electronic ISBN: 978-0-85729-935-2
Print ISBN: 978-0-85729-934-5
DOI: https://doi.org/10.1007/978-0-85729-935-2

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Über dieses Buch

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Chapter 2. Physical Simulation

Chapter 3. Haptic Interaction

Chapter 4. VR System Framework

Chapter 5. Analysis of the VR System

Chapter 6. Summary & Outlook

Backmatter

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