Haptic rendering based on spatial run-length encoding

In this paper, an extendable volumetric representation based on run-lengths called spatial run-length encoding (S-RLE) is presented. The S-RLE representation is developed for a haptic shape modeling system that is based on simulated machining processes. In the system, shape modeling is simulated as virtual material removal processes similar to machining processes with volume-based haptic rendering. The object and the tools are represented by S-RLE. The data structure of S-RLE consists of two cross-referenced databases: one is a stack of lists in geometrical domain, recording the runs describing the space occupation of the object; the other is a table in physical domain, describing the physical properties of each element. The latter is extendable to include more diverse physical properties such as parts composed of heterogeneous materials. Algorithms for geometric operations and haptic rendering based on S-RLE are developed. The proposed S-RLE data structure has the features of efficient memory usage, quick collision detection, inherent representation for heterogeneous objects, and fast visual rendering.     

Haptic applications for molecular structure manipulation

We describe the application of haptic technology to enhance the information available in chemical systems, specifically related to computational drug design. These methods are designed to build upon the visual information presented by molecular viewers and add the sensation of touch, or force feedback. The addition of sensory input can aid in the analysis of molecular structures and the understanding of intermolecular interactions by delivering chemically relevant forces to the end user.     

A Visibility Sphere Marching algorithm of constructing polyhedral models for haptic sculpting and product prototyping

This paper presents a Visibility Sphere Marching algorithm of constructing polyhedral models from Dexel volume models for haptic virtual sculpting. Dexel volume models are used as the in-process models representation during interactive modification in a haptic virtual sculpting system. The stock material represented in a Dexel volume model is sculpted into a designed model using a developed haptic sculpting system. The sculpted Dexel volume models are converted to polyhedral surface models in STL format by the proposed visibility sphere marching algorithm. The conversion turns out to be an interesting and challenging problem. The proposed visibility sphere marching algorithm consists of three sub-algorithms: (i) roof and floor covering, (ii) wall-building, and (iii) hole-filling algorithms. The polyhedral surface models converted from the Dexel volume models can then be input to and processed by available computer-aided manufacturing (CAM) or rapid prototyping systems. The presented technique can be used in virtual sculpting, CAD/CAM, numerically controlled machining verification and rapid prototyping.     

Error-controlled real-time cut updates for multi-resolution volume rendering

Multi-resolution techniques are required for rendering large volumetric datasets exceeding the size of the graphics card's memory or even the main memory. The cut through the multi-resolution volume representation is defined by selection criteria based on error metrics. For GPU-based volume rendering, this cut has to fit into the graphics card's memory and needs to be continuously updated due to the interaction with the volume such as changing the area of interest, the transfer function or the viewpoint. We introduce a greedy cut update algorithm based on split-and-collapse operations for updating the cut on a frame-to-frame basis. This approach is guided by a global data-based metric based on the distortion of classified voxel data, and it takes into account a limited download budget for transferring data from main memory into the graphics card to avoid large frame rate variations. Our out-of-core support for handling very large volumes also makes use of split-and-collapse operations to generate an extended cut in the main memory. Finally, we introduce an optimal polynomial-time cut update algorithm, which maximizes the error reduction between consecutive frames. This algorithm is used to verify how close to the optimum our greedy split-and-collapse algorithm performs.     

触觉显示的人机交互研究及应用

触觉显示是应用触觉刺激表示信息,通过触觉来显示和传递信息。首先介绍了触觉显示的研究背景,回顾了触觉显示的研究历史和国内外的研究现状,指出了触觉显示方面主要的研究领域。其次通过对现有的触觉显示的人机交互研究及应用所取得成果的分析,对当前触觉显示的人机交互研究及应用的发展进行了总结,最后对触觉显示的人机交互研究及其应用前景提出了一些展望,旨在帮助研究人员和工程师今后更好地研究、开发和利用触觉显示技术。     

Haptic function evaluation of multi-material part design

Recently haptic shape modeling has got a momentum in industrial and conceptual design. In this paper, a real-time haptic interface of synthesized shape modeling and haptic function evaluation of product design for multi-material part is presented. Due to the advancement of manufacturing technologies, multi-material is increasingly employed by industrial designers as a means for increasing the appeals of a product while also adding functional capability. Multi-material part manufacturing processes allow designers to select different materials for different portions of a product in order to improve the material-function compatibility for the overall product. For quick design verification, the shape design and function evaluation are implemented in the same haptic environment where a load can be applied to a part design using a haptic device and at the same time the combined reaction of the part in terms of displacement and reaction can be visualized and felt by the user. The intuitive correlation between the applied force and incurred displacement (or deflection) provides an instant evaluation of the stiffness of a part design. The proposed methodology is illustrated through a case study: the design of a toothbrush.     

Haptic modeling in the conceptual phases of product design

The paper presents the results of a research project aimed at developing an innovative system for modeling industrial products based on haptic technology. The system consists of a Computer Aided Design (CAD) system enhanced with intuitive designer-oriented interaction tools and modalities. The system integrates innovative six degrees of freedom (DOF) haptic tools for modeling digital shapes, with sweep operators applied to class-A surfaces and force computation models based on chip formation models. The system aims at exploiting designers’ existing skills in modeling products, improving the products design process by reducing the necessity of building several physical models for evaluating and testing the product designs. The system requirements have been defined observing designers during their daily work and translating the way they model shapes using hands and craft tools into specifications for the modeling system and the haptic tool. The system prototype has been tested by designers who have found it intuitive and effective to use.     

Finding the Latent Semantics of Haptic Interaction Research: A Systematic Literature Review of Haptic Interaction Using Content Analysis and Network Analysis

As interest in multimodal and tangible interfaces is increasing in the field of human–robot interaction and virtual reality, haptics has been researched across areas such as engineering, computer science, psychology, and neuroscience. The main objective of the study was to construct a comprehensive review of the current haptic‐related literature based on quantitative data derived from content analysis and network analysis. Using the results of content analysis and network analysis of 6,000 research articles on haptic interaction, the haptic‐related literature was classified into two categories: 1) studies on technologies providing haptic stimuli and 2) studies on the human perception of haptic stimuli. Emotions in haptic feedback and haptic perception characteristics of various body sites were identified as potential research topics for further investigation. Greater research effort on understanding human haptic sensation and perception using the proposed systematic approach could accelerate the development of haptic interaction technology.     

A reverse engineering method based on haptic volume removing

This paper presents a new reverse engineering methodology that is based on haptic volume removing. When a physical object is to be digitized, it is first buried in a piece of virtual clay that is generated with the help of a fixture. Now digitizing the physical object is by simply chipping away the virtual clay with a position tracker that is attached to a haptic device PHANToM^®. While chipping away the clay, the user can see on the computer monitor what is emerging and at the same time feel the chipping force from the haptic device. By so doing, reverse engineering is seamlessly integrated into haptic volume sculpting that is now widely used for conceptual design. Furthermore, the proposed method has eliminated the need to merge point clouds that are digitized from different views using current digitizers. The virtual clay volume is represented by a spatial run-length encoding scheme. A prototype system has been developed to demonstrate the feasibility of the proposed new method through a case study. The strengths and weaknesses of the presented method are analyzed and the applicability is discussed.     

Nonlinear viscoelastic contact and deformation of freeform virtual surfaces

This article is concerned with the haptic deformation display of discrete viscoelastic surfaces by means of a human fingertip. The virtual surface of a deformable quadrilateral mesh is interactively deformed by a Kelvin–Voigt soft fingertip model attached to the end-effector of a haptic interface device. In achieving this task, a nonlinear constitutive model approximating experimental data from literature is developed for determining the contact point deformations. By employing a new kernel weighting function, the deformations are distributed dependently on the discrete surface topology based on a nonlinear spring–damper net around the contact location. For illustration and evaluation of the proposed approach, a parallel robotic device with a constraint-based controller is adopted. The grip of the device is moved by the user to feel a sense of touch as the soft fingertip deforms the mesh surface of an ex vivo porcine liver tissue. Experimental data indicates stable realistic interactions thorough mechanical coupling between the soft fingertip and the deforming liver tissue. Dynamic response data of liver show rate-dependent hysteretic deformations and match closely with experimental indentation data from literature. A thorough analysis of mesh node count on the sample rate and the rendering quality is also presented.     

Haptic two-finger contact with textiles

Real-time cloth simulation involves many computational challenges to be solved, particularly in the context of haptic applications, where high frame rates are necessary for obtaining a satisfying experience. In this paper, we present an interactive cloth simulation system that offers a compromise between a realistic physics-based simulation of fabrics and a haptic application meeting high requirements in terms of computation speed. Our system allows the user to interact with the fabric using two fingers. The required performance of the system is achieved by introducing an intermediate layer responsible for the simulation of the small part of the surface being in contact with the fingers. Additionally we separate the possible contact situations into different cases, each being individually handled by a specialised contact algorithm.

图像的力/触觉表达技术研究综述

总结了图像的力/触觉表达技术研究的现状及特点,分析了图像的力/触觉表达研究中存在的问题,并展望了该技术的发展前景.     

基于PROFIBUS-DP的钢铁造型生产线PLC控制系统设计

介绍了某钢铁厂造型生产线PLC控制系统技术改造方案．本系统采用PROFIBUS—DP过程现场总线技术实现主站与从站的数据交换和分布式控制功能．通过上位机进行集中控制，完成可视化人机操作界面、通信、联网等功能。该方案适用于其它工业控制系统。     

一种虚拟手术二维力觉交互装置的力学模型

对力交互装置在虚拟手术巾有着广泛的应用,作为基础研究,提出一种二维力觉交互装置的反馈力模型,通过模拟虚拟器械与肌肉组织和骨骼碰撞时的受力情况,验证模型的合理性。首先,根据人体组织的生物力学性能,参照Kamopp模型和胡克定律提出了系统的反馈力模型;然后针对系统的性能指标,通过对肌肉和骨骼两种组织的碰撞实验,验证了设备在虚拟手术过程中反馈力实现效果。仿真结果显示,反馈力方法能较准确地仿真力的变化,准确地感知骨骼的位置,对于虚拟手术系统的实用性具有重要意义。     

Constructive sculpting of heterogeneous volumetric objects using trivariate B-splines

This paper deals with modeling heterogeneous volumetric objects as point sets with attributes using trivariate B-splines. In contrast to homogeneous volumes with uniform distribution of material and other properties, a heterogeneous volumetric object has a number of variable attributes assigned at each point. An attribute is a mathematical model of an object property of an arbitrary nature (material, photometric, physical, statistical, etc.). In our approach, the function representation (FRep) is used as the basic model for both object geometry and attributes represented independently using real-valued scalar functions of point coordinates. While FRep directly defines object geometry, for an attribute it specifies a space partition used to define the attribute function. We propose a volume sculpting scheme with multiresolution capability based on trivariate B-spline functions to define both object geometry and its attributes. A new trivariate B-spline primitive is proposed that can be used as a leaf in an FRep constructive tree. An interactive volume modeler based on trivariate B-splines and other simple primitives is described, with a real-time repolygonization of the surface during modeling. We illustrate that the space partition obtained in the modeling process can be applied to define attributes for the objects with an arbitrary geometry model such as BRep or homogeneous volume models.     

Development of a multi-resolution framework for NUBS

The piecewise polynomial B-spline representation is a flexible tool in Computer Aided Geometric Design (CAGD) for representing and designing the geometric objects. In the field of Computer Graphics (CG), Computer Aided Design (CAD), or Computer Aided Engineering (CAE), a very useful property for a given spline model is to have locally supported basis functions. This allows localized modification of the shape. Unfortunately this property can also become a serious disadvantage when the user wishes to edit the global shape of a complex object. A multi-resolution representation is proposed as a solution to alleviate this problem.In this work, we propose a multi-resolution representation for Non-uniform B-splines (NUBS). The proposed multi-resolution model has three features that it uses control point decimation strategy for decomposing NUBS curves and it is efficient in both time and space utilization. A comparative study of the proposed work is also made with an alternate approach in the literature, which is based upon knot decimation.     

B样条曲线的多分辨编辑新算法

概述小波分析与重构的基本理论,将小波分解的理论应用于B样条曲线的多分辨编辑中,提出一种小波分析和重构的新算法。该算法利用方程组的增广矩阵为类带状矩阵或者稀疏矩阵这一特点,运用简单的矩阵的行初等变换,将类带状矩阵或者稀疏矩阵化成容易接受的行简化矩阵,解方程组,使小波分解与重构的过程快速准确,使从事相关工作的技术人员更容易理解和接受。     

A CAD-CAE integration approach using feature-based multi-resolution and multi-abstraction modelling techniques

In spite of the widespread use of CAD systems for design and CAE systems for analysis, the two processes are not well integrated because CAD and CAE models inherently use different types of geometric models and there currently exists no generic, unified model that allows both design and analysis information to be specified and shared. In this paper, a new approach called the CAD/CAE-integrated approach is proposed and implemented by a feature-based non-manifold modelling system. The system creates and manipulates a single master model containing different types of all of the geometric models required for CAD and CAE. Both a solid model (for CAD) and a non-manifold model (for CAE) are immediately extracted from the master model through a selection process. If a design change is required, the master model is modified by the feature modelling capabilities of the system. As a result, the design and analysis models are modified simultaneously and maintained consistently. This system also supports feature-based multi-resolution and multi-abstraction modelling capabilities providing the CAD model at different levels of detail and the CAE model at various levels of abstraction.     

Haptic feedback and control of a flexible surgical endoscopic robot

A flexible endoscope could reach the potential surgical site via a single small incision on the patient or even through natural orifices, making it a very promising platform for surgical procedures. However, endoscopic surgery has strict spatial constraints on both tool-channel size and surgical site volume. It is therefore very challenging to deploy and control dexterous robotic instruments to conduct surgical procedures endoscopically. Pioneering endoscopic surgical robots have already been introduced, but the performance is limited by the flexible neck of the robot that passes through the endoscope tool channel. In this article we present a series of new developments to improve the performance of the robot: a force transmission model to address flexibility, elongation study for precise position control, and tissue property modeling for haptic feedback. Validation experiment results are presented for each sector. An integrated control architecture of the robot system is given in the end.     

Fast variational design of multiresolution curves and surfaces with B-spline wavelets

Multiresolution modeling provides a powerful tool for complex shape editing. To achieve a better control of deformations and a more intuitive interface, variational principles have been used in such multiresolution models. However, when handling multiresolution constraints, the existing methods often result in solving large optimization systems. Hence, the computational time may become too excessive to satisfy the requirements for interactive design in CAD. In this paper, we present a fast approach for interactive variational design of multiresolution models. By converting all constraints at different levels to a target level, the optimization problem is formulated and solved at the lower level. Thus, the unknown coefficients of the optimization system are significantly reduced. This improves the efficiency of variational design. Meanwhile, to avoid smoothing out the details of the shape in variational modeling, we optimize the change in the deformation energy instead of the total energy of the deformed shape. Several examples and the experimental results are given to demonstrate the effectiveness and efficiency of this approach.