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Haptic Interaction with Deformable Objects
Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The integration of haptics into virtual environments has triggered a new era by allowing interaction with virtual objects through force feedback in a number of fields. Medicine has been the field with highest potential benefit through improved realism and immersion. Not only have virtual environments become superior to traditional medical training methods due to cost-efficiency, repeatability, and objective assessment but the idea of surgery rehearsal by using patient specific data has been raised as well.

Achieving sufficient realism in haptics has been a significant challenge due to performance requirements. In order to provide a stable and smooth feedback to the user, the update rates of force feedback need to be in the range of 1~kHz, which restricts the solution time for real-time interactive applications. Realism, on the other hand, demands advanced algorithms capable of simulating physical properties. These advanced algorithms have a high computational burden, taking significant amounts of time and their real-time use, therefore, mostly requires simplification of the virtual scene affecting realism.

During palpation, information is transferred to the hand from the local neighbourhood of contact. In deformation simulations, it is therefore common to use a multiresolution scheme, where the local region is modelled with a higher resolution than more distant regions, and at higher update rates. This approach saves computational power, however the less elaborate modelling in the more remote regions affects accuracy. This thesis presents a pipeline to analyse the error introduced by multiresolution techniques. The idea is to estimate how simulation parameters lead to different error magnitudes, as a preprocessing step. This information can subsequently be used for monitoring the error in real-time, or for adjusting simulation parameters to keep the error under a desired limit.

There is a trade-off between accuracy/error and computation time required. In an ideal situation, this error should be kept under perceivable levels. Levels of perception is a topic that has been surveyed in psychophysics among other aspects of touch. It has been shown that differences smaller than a ratio of a reference signal, such as force or stiffness, cannot be perceived. Evaluating the exact value of this ratio, however, is nontrivial since there are many secondary factors having a significant impact, such as the multimodal input. This thesis presents the analysis of some factors affecting the sense of touch that were shown to have such impact. Effects of exploratory procedures on stiffness perception were examined through user studies, followed by another study indicating the significant effects of stiffness gradient.

Medical data, such as MR and CT, has much higher resolution than is practically used for deformable meshes. It has been common practice to model deformation behaviour by a mesh with lower resolution than is used for visual representation. Lastly, this thesis presents an approach to introduce high-resolution information. The proposed algorithm allows for the detection of inhomogeneous structures beneath a surface. This can be applied in situations similar to the diagnosis of tumours by palpation. The approach is independent of mesh structure and resolution, and can be integrated into any proxybased haptic rendering algorithm. This makes the algorithm a complementary choice for deformation simulation.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2013. , 72 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1522
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-92804ISBN: 978-91-7519-615-2 (print)OAI: oai:DiVA.org:liu-92804DiVA: diva2:622593
Public defence
2013-06-05, Domteatern, Visualiseringscenter C, Kungsgatan 54, 602 33 Norrköping, 09:15 (English)
Opponent
Supervisors
Available from: 2013-05-22 Created: 2013-05-22 Last updated: 2014-10-08Bibliographically approved
List of papers
1. Dynamic Deformation Using Adaptable, Linked Asynchronous FEM Regions
Open this publication in new window or tab >>Dynamic Deformation Using Adaptable, Linked Asynchronous FEM Regions
2009 (English)In: Spring Conference on Computer Graphics / [ed] Helwig Hauser and Stephen N. Spencer, New York: ACM , 2009, 197-204 p.Conference paper, Published paper (Refereed)
Abstract [en]

In order to simulate both physically and visually realistic soft tissue deformations, the Finite Element Method (FEM) is the mostpopular choice in the literature. However it is non-trivial to modelcomplex behaviour of soft tissue with sufficient refresh rates, especiallyfor haptic force feedback which requires an update rate ofthe order of 1 kHz. In this study the use of asynchronous regions isproposed to speed up the solution of FEM equations in real-time. Inthis way it is possible to solve the local neighborhood of the contactwith high refresh rates, while evaluating the more distant regions atlower frequencies, saving computational power to model complexbehaviour within the contact area. Solution of the different regionsusing different methods is also possible. To attain maximum efficiencythe size of the regions can be changed, in real-time, in responseto the size of the deformation.

Place, publisher, year, edition, pages
New York: ACM, 2009
Keyword
Finite Element Method, surgery simulations, haptics
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-18053 (URN)10.1145/1980462.1980500 (DOI)978-1-4503-0769-7 (ISBN)
Conference
SCCG '09 Spring Conference on Computer Graphics, April 23-25, Budmerice, Slovakia
Available from: 2009-06-08 Created: 2009-05-04 Last updated: 2014-10-08Bibliographically approved
2. An Error Analysis Model for Adaptive Deformation Simulation
Open this publication in new window or tab >>An Error Analysis Model for Adaptive Deformation Simulation
2012 (English)Conference paper, Published paper (Other academic)
Abstract [en]

With the widespread use of deformation simulations in medical applications, the realism of the force feedback has become an important issue. In order to reach real-time performance with sufficient realism the approach of adaptivity, solution of different parts of the system with different resolutions and refresh rates, has been commonly deployed. The change in accuracy resulting from the use of adaptivity, however, has been been paid scant attention in the deformation simulation field. Presentation of error metrics is rare, while more focus is given to the real-time stability. We propose an abstract pipeline to perform error analysis for different types of deformation techniques which can consider different simulation parameters. A case study is also performed using the pipeline, and the various uses of the error estimation are discussed.

Keyword
physically-based, deformation, multiresolution, perception, error, analysis
National Category
Interaction Technologies
Identifiers
urn:nbn:se:liu:diva-79904 (URN)978-1-61208-177-9 (ISBN)
Conference
ACHI 2012, The Fifth International Conference on Advances in Computer-Human Interactions, January 30 2011, to February 4 2012, Valencia, Spain
Available from: 2012-08-28 Created: 2012-08-15 Last updated: 2014-10-08Bibliographically approved
3. Analysis of the JND of Stiness in Three Modesof Comparison
Open this publication in new window or tab >>Analysis of the JND of Stiness in Three Modesof Comparison
Show others...
2011 (English)In: HAID'11 Proceedings of the 6th international conference on Haptic and audio interaction design, Springer Berlin/Heidelberg, 2011, 22-31 p.Conference paper, Published paper (Other academic)
Abstract [en]

Understanding and explaining perception of touch is a non-trivial task. Even seemingly trivial differences in exploration may potentially have a significant impact on perception and levels of discrimination. In this study, we explore different aspects of contact related to stiffness perception and their effects on the just noticeable difference (JND) of stiffness are surveyed. An experiment has been performed on non-deformable, compliant objects in a virtual environment with three different types of contact: Discontinuous pressure, continuous pressure and continuous lateral motion. The result shows a significantly better discrimination performance in the case of continuous pressure (a special case of nonlinearity), which can be explained by the concept of haptic memory. Moreover, it is found that the perception is worse for the changes that occur along the lateral axis than the normal axis.

Place, publisher, year, edition, pages
Springer Berlin/Heidelberg, 2011
Series
Lecture Notes in Computer Science, ISSN 0302-9743 (print), 1611-3349 (online) ; 6851
Keyword
perception, stiffness, JND, exploratory procedures, haptics
National Category
Interaction Technologies
Identifiers
urn:nbn:se:liu:diva-79898 (URN)10.1007/978-3-642-22950-3_3 (DOI)978-3-642-22949-7 (ISBN)978-3-642-22950-3 (ISBN)
Conference
6th international conference on Haptic and audio interaction design (HAID 2011), Kusatsu, Japan, 25-26 August
Available from: 2012-08-28 Created: 2012-08-15 Last updated: 2015-09-22Bibliographically approved
4. The Effect of the Stiffness Gradient on the Just Noticeable Difference between Surface Regions
Open this publication in new window or tab >>The Effect of the Stiffness Gradient on the Just Noticeable Difference between Surface Regions
2012 (English)In: Haptics: Perception, Devices, Mobility, and Communication: International Conference, EuroHaptics 2012, Tampere, Finland, June 13-15, 2012. Proceedings, Part I / [ed] Poika Isokoski, Jukka Springare, Springer Berlin/Heidelberg, 2012, 282-292 p.Chapter in book (Refereed)
Abstract [en]

This book and its companion volume, LNCS 7282 and 7283, constitute the refereed proceedings of the 8th International Conference, EuroHaptics 2012, held in Tampere, Finland, in June 2012. The 99 papers (56 full papers, 32 short papers, and 11 demo papers) presented were carefully reviewed and selected from 153 submissions. Part I contains the full papers whereas Part II contains the short papers and the demo papers.

Place, publisher, year, edition, pages
Springer Berlin/Heidelberg, 2012
Series
Lecture Notes in Computer Science, ISSN 0302-9743 (print), 1611-3349 (online) ; 7282
Keyword
Computer science, Multimedia systems, Computer vision, User Interfaces and Human Computer Interaction, Information Systems Applications, Computers and Society, Multimedia Information Systems, Computer Imaging, Vision, Pattern Recognition and Graphics, Computers and Education
National Category
Interaction Technologies
Identifiers
urn:nbn:se:liu:diva-79905 (URN)10.1007/978-3-642-31401-8_26 (DOI)978-3-642-31400-1 (ISBN)e-978-3-642-31401-8 (ISBN)
Available from: 2012-08-28 Created: 2012-08-15 Last updated: 2014-11-27Bibliographically approved
5. Anisotropic Virtual Coupling with Energy-Based Deflection for Palpating Inhomogeneous Compliant Objects
Open this publication in new window or tab >>Anisotropic Virtual Coupling with Energy-Based Deflection for Palpating Inhomogeneous Compliant Objects
2013 (English)In: Proceedings of the IEEE World Haptics Conference, IEEE , 2013, 115-120 p.Conference paper, Published paper (Refereed)
Abstract [en]

Virtual coupling, a spring-damper system between the haptic probe and its virtual representation, the proxy, is one of the most common approaches for haptic rendering. We have extended the virtual coupling by updating the spring stiffness, sometimes used to simulate compliance of a material, depending on the direction between the proxy and the probe. This anisotropic variation of the stiffness is used in exploring inhomogeneities beneath the surface allowing detection of rigid structures even when they are obscured by another structure beneath the surface. In addition, we also compensate for the energy variation of the spring to maintain passivity and increase realism. User studies were performed to survey the success rate in the detection of obscured rigid bodies beneath the surface with the modified virtual coupling algorithm and the improvement of shape perception for sub-surface objects with the additional energy compensation term providing gradient information. We also discuss potential benefits of the proposed methods as basic extensions to well-known haptic rendering algorithms which are both simpler and yield improved performance over traditional deformation simulationtechniques.

Place, publisher, year, edition, pages
IEEE, 2013
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-92802 (URN)10.1109/WHC.2013.6548394 (DOI)978-1-4799-0087-9 (ISBN)
Conference
IEEE World Haptics Conference, WHC 2013; Daejeon; South Korea
Available from: 2013-05-22 Created: 2013-05-22 Last updated: 2014-12-04Bibliographically approved
6. High Resolution Enhancement in Deformation via Anisotropic Virtual Coupling
Open this publication in new window or tab >>High Resolution Enhancement in Deformation via Anisotropic Virtual Coupling
2013 (English)Manuscript (preprint) (Other academic)
Abstract [en]

Achieving sufficient realism in deformation simulations requires consideration  of complex physical properties. The computational burden of modelling these properties requires the use of low resolution meshes to attain real time interactive performance. Medical data such as MR and CT, on the other hand, have much higher resolutions than can be practically used in deformation simulations. This results in significant amount of information loss, degenerating the ability to perceive variations in the data, especially inhomogeneities. In this paper, we address this issue by employing surfacerendering algorithms which can provide high resolution information from beneath the surface. An experiment was performed in a scenario simulating inhomogeneities of bone structure under the skin. Results have shown significant improvement for detecting inhomogeneities within deformable data while palpating the surface.

Keyword
Deformation, virtual coupling, anisotropy, haptics
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-92803 (URN)
Available from: 2013-05-22 Created: 2013-05-22 Last updated: 2014-10-08Bibliographically approved

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Kocak, Umut

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