Showing papers presented at "Virtual Environments, Human-Computer Interfaces and Measurement Systems in 2009"

Investigating the influence of temporal intensity changes on apparent movement phenomenon

Abstract: This paper aims at investigating the influence of the temporal intensity changes of two low-resolution vibrotactile actuators on the apparent movement phenomenon. In our work, we exploit two human sensory illusions called funneling illusion and apparent movement phenomenon. By temporarily varying the intensities of two adjacent vibrating actuators located on the dorsal of the human forearm, we obtained the illusion of a continuous movement of one tactile stimulus. In this work, we investigated the quality of the apparent movement according to the intensity change of the vibrating motors in a linear and logarithmic pattern. Psychophysical experiments revealed an interesting relationship between the distance and orientation of the two vibrating actuators with the preferred intensity variation, which are presented in this paper.

Study on EEG-based mouse system by using brain-computer interface

Abstract: This paper aimed to design an EEG-based mouse system by using brain-computer interface (BCI) to move a cursor on a computer display. This system to provide an alternative communication or control channel for patients with severe motor disabilities. Such patients might become able to select target on a computer monitor by moving a cursor through mental activity. The user could move the cursor just through imaging his/her hand operation on mouse without any actual action while the movement direction that he/she wanted to choose was lighted in the cue line of four-direction choice circulation. This system used an adaptive algorithm to recognize cursor control patterns in multichannel EEG frequency spectra. The algorithm included preprocessing, feature extraction, and classification. A Fisher ratio was defined to determine the characteristic frequency band. The spectral powering this band was calculated as feature parameter to distinguish the task state of imagination of hand movements (IHM) from free state of non-IHM. Mahalanobis distance classifier was employed to recognize the effective task pattern and produce the trigger signal as cursor controller. Relevant experiment results showed that this system achieved 80% accuracy for IHM task/free pattern classification. This EEG-based mouse system is feasible to drive the cursor's four-direction movement and may provide a new communication and control option for patients with severe motor disabilities.

Gait recognition based on multiple views fusion of wavelet descriptor and human skeleton model

Abstract: Gait recognition is a relatively new subfield in biometric recognition, which attempts to recognize people from the way they walk or run. This paper discusses silhouette-based feature descriptor. Human silhouette geometry is generated by boundary tracking approach and resampled to a normalized format. Boundary-centroid distance is proposed to describe gait modality. Then, we apply wavelet transform to boundary-centroid distance, and extract wavelet descriptor. At the same time, we obtain the human skeleton model and extract bodys dynamic parameters to express gait modality. We carry out human identification based on SVM using the two kinds of gait feature. The performances based on the two features are compared. Multiple feature fusion and multiple views fusion are carried out and the recognition results demonstrate that the performance of multiple features and multiple views recognition is better than any single feature and single view recognition.

Path-planning and manipulation of nanotubes using visual and haptic guidance

Abstract: This paper presents a VR toolkit for path planning and manipulation of nanotube. The toolkit is capable of modeling the interactions between an AFM tip and carbon nanotubes on a substrate surface and generating optimum and safe manipulation paths. In addition, haptic guides were designed to help the user to follow the calculated paths, to avoid obstacles.

Robust pupil detection by image difference with positional compensation

Abstract: Remote and noncontact, video camera-based pupil detection techniques are useful for human interface and human monitoring devices. In general, it is difficult to detect pupils without illumination. However, if using near-infrared illuminations, pupil detection becomes dramatically robust. We formerly proposed a robust pupil detection technique using two light sources and the image difference method. In the pupil detection technique, the two light sources alternately produce the bright and dark pupil images every field, and then the successive bright and dark pupil images are differentiated. In the obtained difference image, the pupil image can be easily detected because the background image except for pupils is basically canceled out. The above-mentioned pupil detection technique has some advantages compared to pupil detection techniques from the bright or dark pupil image; robust for high and dark ambient lighting conditions and for eye-glasses reflection, and so on. However, there is the following weak point: due to the time discrepancy in acquiring the bright and dark pupil images, its effect is spoiled when the pupils move. In this paper, three methods which improve this problem are proposed. The experimental results showed their effectiveness.

3D virtual reality simulator for planetary rover operation and testing

Abstract: This paper describes a computer-simulated virtual reality environment for planetary rover operation and testing. The proposed 3D Virtual Rover Operation Simulator (VROS) consists of rover model, perception of the planetary surface, and rover-terrain contact model, which provides a simulation platform to test and validate different rover chassis design, navigation and locomotion algorithms, and to support rover operation. Lab-based experiments have been carried out and results can demonstrate various functions of VROS and its performance.

An adaptive virtual simulation and real-time emergency response system

Abstract: Virtual simulation has been playing an important role in many areas including gaming, training, e-learning, and etc. At the mean time, real-time emergency response system is attracting more and more attention due to its significance to reduce the casualties and properties lost when disasters come. Indeed, a highly responsive and effective real-time response system depends on a well designed architecture, in particular, a distributed virtual simulation environment which not only can train the emergency response personnel, but also can be used as a core real-time strategy and response system. In this paper, we propose an integrative and adaptive distributed real-time simulation environment which aims at providing a more efficient and flexible virtual environment to meet the requirement of today's high-end emergency response class of applications. Our proposed system is based in service oriented design and most advanced P2P network technique. The goal of our system is to build a robust software framework to make the real-time emergency response system more flexible and more scalable.

Authoring edutainment content through video annotations and 3D model augmentation

Abstract: In this paper, a real world based interaction metaphor has been adopted to facilitate learning about physical objects in an entertaining fashion. The proposed system incorporates an intuitive video annotation approach in order to catalog and author information about physical learning objects in a scene. The system uses augmented 3D visualization schemes and provides adequate visual cues in order to leverage the hand gesture and voice based interactions with the learning objects. These real world interaction techniques make the system transparent from the young learners and help them to become engaged in their learning activities.

A 4-layer flexible virtual hand model for haptic interaction

Abstract: Virtual hand interactions play key roles in virtual environments. The recent addition of force feedback to virtual reality simulations has enhanced their realism, especially when dexterous manipulation of virtual objects is concerned. In the past decades, much effort has been made on virtual hand modeling from the perspectives of computer animation and human computer interaction. However, much less attention is paid on haptic modeling of flexible virtual hand. In this paper, we propose a 4-layer flexible virtual hand model for virtual hand haptic interaction. The skin layer, kinematics layer, collision detection layer and haptic layer are integrated into a sophisticated virtual hand to simulate the human hands natural anatomy in its appearance and motion, and to reflect the area contact feature of force feedback datagloves. The infrastructure and details of the flexible virtual hand model are discussed. Experimental results show that the proposed flexible virtual hand demonstrates good performance in virtual hand haptic applications.

Dataglove calibration with constructed grasping gesture database

Abstract: Data glove is widely used in the area of Human Computer Interaction (HCI), but its precise calibration is still an unsettled question. This paper establishes a human hand model suit for general-purpose instrumented glove application and presents a reliable and expedient calibration routine. Our calibration method can be simply carried through without the need for auxiliary calibration hardware, while still producing high visual-fidelity performance.

DreamWorld: CUDA-accelerated real-time 3D modeling system

Abstract: 3D modeling plays an important role in virtual reality interaction, immersive tele-presence and other applications. A CUDA-accelerated real-time 3D modeling system is presented in this paper. It captures multi-view images of objects and achieves real-time accurate visual hull reconstruction with texture mapping. The system includes off-line camera calibration and on-line visual hull modeling based on our DreamWorld hardware. The multi-camera based modeling process is composed of distributed image acquisition, silhouette extraction, data transmission, visual hull computation and rendering. Initially, the volumetric visual hull is computed through intersection test of voxels with each silhouette and then, a CUDA-based simplified exact marching cubes algorithm is put forward to get a polyhedral mesh model for texture mapping and rendering. Preliminary experimental results from both synthetic and real data show its accuracy, stability and real-time performance.

Study on underwater wet arc welding training with haptic device

Abstract: Underwater wet arc welding is hard and sometime involves risks to welder divers. To help welder divers gain their underwater wet arc welding skills, a new underwater wet arc welding training method is proposed in this paper based on haptic device. In this method, self-consuming technique is focused on, and fillet welding in different positions is mainly discussed. The haptic device simulates the impacts of seawater acted on an electrode holder, and also guides a trainee to maintain the virtual electrodes proper moving path, proper travel speed, proper compensation speed, proper work angle and the lead angle, and proper arc length. The proposed system is implemented using a Phantom Desktop, and its feasibility is verified. The introduction of a haptic device makes the welder divers training for underwater wet arc welding risk free, convenient and efficient.

A virtual classroom interface for student participation measurement

Abstract: The aim of this paper is to describe the methodology employed in the construction of a virtual classroom tool based on a collaborative learning interface, also able to analyze and measure users data for assessing the application performance and evaluating the level of students participation in the proposed e-learning model. The future target will be based on the comparison of the results obtained during the experimentation phase for studying the best way to create a personalized learning path.

A practical approach for constructing an adaptive tutoring model based on concept map

Abstract: The study proposes a complete and practical adaptive tutoring learning model (ATM). ATM calculates every learners score of each concept and indicates his/her misconceptions. Then apply fuzzy association rule mining approach to find out all the prerequisite relationship between concepts and concepts, and to construct a concept map. Based on the constructed concept map and misconceptions, ATM determines his/her main learning barriers. Finally, for solving learning barriers, ATM will suggest the learner an adaptive learning material by analyzing the ratios of the concepts contained in each material.

Path planning for robot assisted femur shaft fracture reduction : A preliminary investigation

Abstract: When doing femur fracture reduction surgery, both the patient and the surgeon are exposed to a great amount of radiation, which is harmful to their health. Computer assisted orthopaedic surgery (CAOS) is a less invasive approach for its ability to reduce the usage of image intensifier. The authors have developed a six degree of freedom (DOF) parallel-serial surgical robot named D'cros(Dual Cartesian robot for orthopaedic surgeon) for fracture reduction surgery. To perform automatic fracture reduction surgery, reduction path for D'cros is needed. This paper presents an initial investigation of an automatic reduction path planning algorithm based on the shortest linear path.

Analysis of multi-hinge compliant needle insertion

Abstract: This article presents a multi-hinge compliant needle in minimally invasive surgery. This flexible needle has bevel tip and compliant hinges. The force acting on the bevel-tip surface can cause large turning curvature and turn angle. A feasible algorithm for path control of the needle thrusting is developed. A detail explanation of the algorithm is given. The main objectives of this algorithm are to control the needle thrusting trajectory and to avoid collision with the important organs and nerves in the human body while insertion.

Accessibility analysis for CMM inspection planning by means of haptic device and STL representation

Abstract: Inspection planning plays one of important roles in examining a manufactured part in 3D sizes, positions and forms using coordinate measuring machine (CMM). Accessibility Analysis must be done during CMM inspection planning. Usually, accessibility analysis is based on the computation of a part's computer-aided design (CAD) model and the model of a probe. In this paper, a new accessibility analysis method for CMM inspection planning is proposed based on a haptic device and STL representation. Different collision modes are analyzed. A quick collision detection algorithm is given, which is based on the STL representation. Force response is analyzed to distinguish between an occurred collision and a normal contacting of the tip to an inspection point. Using STL representation, the virtual CMM probe unit model is more precise, which results in the accessibility analysis implemented precisely. With the force feedback generated by a Phantom Desktop haptic device, the accessibility analysis is performed much easier.

A crowd evacuation simulation model based on 2.5-dimension cellular automaton

Abstract: A new idea of 2.5 dimensional cellular automaton models is provided. It discloses that the environmental altitude is an important factor which has an active function on the crowd evacuation model related to stadium. The research uses the agent technology in virtual agent's movement-decision-making for their evacuating action. It suggests using the attraction weighing value of cellular-automaton-grid as an important parameter, which considers the objective factor, for selecting agent's suitable evacuation path. Meanwhile, the agent's subjective factor, which would influence their evacuation, has also been considered. The agent's evacuating movement regulation is established by these two factors. And finally, a practical and well-visibility system for crowd evacuation has been developed; a related instance is used to prove that the 2.5D-CA-model is practicable and reasonable for crowd evacuating simulation.

Virtual fixture based haptic rendering of handwriting

Abstract: Virtual fixture is widely used for motor skill assistance and training. For motor skills involving long and self-intersecting trajectories with variational curvatures, existing methods based on analytic representation of curves can not meet real time and stability requirements of haptic rendering. In this paper, a simple and efficient hierarchical structure is proposed to represent the time ordered geometry of the desired trajectory. The minimum distance from the position of the tool to the desired trajectory is calculated by filtering impossible segments while traversing the hierarchy. To avoid the force discontinuity caused by the singularity of the absolute minimum distance, a constraint conversion method is proposed. The experiments verified that the proposed method satisfied real time and stability requirements of haptic rendering. It enables applications of virtual fixture for assistance and training in handwriting, surgery operation and other skills involving complex trajectories.

Identification of humans using infrared gait recognition

Abstract: Human body is a natural emitter of infrared ray. Usually the body temperature is different from that of surrounding. This leads to gray-scale difference between human body and background in infrared thermal image. So the method of infrared thermal imaging was presented to classify gaits. Firstly, infrared videos of 23 subjects were collected by using infrared thermal camera. Body silhouettes were extracted and normalized to obtain the gait feature image. Then the wavelet transform was combined with invariant moments to compute the moment parameters based on integral model. The gait feature image was simplified to extract the parameters based on the body skeleton. Finally, the parameters were applied to support vector machine for classification. This method achieved 71%∼92% for the probability of correct recognition. The results showed that it was insensitive for loading objects (backpack and volleyball) to recognize gaits in infrared video. Also it is easy to detect the moving human body during the whole day.

Indirect biomechanics measurement on shoulder joint moments of walker-assisted gait

Abstract: The walker is a fundamental rehabilitation device and provides patient external mechanical support. A new measurement and analysis method was proposed to investigate the changes in shoulder joint moments that occur with the use of a front-wheeled walker. A strain gauge-based walker instrumentation system was developed to monitor the hand loads during walker-assisted walking and integrated with an upper extremity biomechanical model. Preliminary system data were collected for twelve subjects following informed consent. Bilateral upper extremity kinematic data were acquired with a six-camera motion analysis system. Internal joint moments at the shoulder were determined in the three clinical planes using the inverse dynamics method. Results showed that during a walker-assisted gait shoulder joint moments mainly distributed in the walker stance period. There was a noted demand on the shoulder adductor in the coronal plane with the greatest record as 0.431 N•m/kg•m. An interesting “bare phase” of mean shoulder joint moments was also found in phase angle [−240°, 340°] of gait cycle. Complete description of shoulder joint moments of walker-assisted gait may provide insight into walker use parameters and rehabilitative strategies.

HMM-based vowel and consonant automatic recognition in Cued Speech for French

Abstract: In this paper, hidden Markov models (HMM)-based vowel and consonant automatic recognition in Cued Speech for French are presented. Cued Speech is a visual communication mode which uses handshapes in different positions and in combination with lip-patterns of speech, makes all the sounds of spoken language clearly understandable to deaf and hearing-impaired people. The aim of Cued Speech is to overcome the problems of lipreading and thus enable deaf children and adults to fully understand a spoken language. Previously, the authors have reported experimental results on vowel recognition in Cued Speech for French. This study, further investigates the vowel recognition, and also reports automatic consonant recognition experiments in Cued Speech for French. In addition, isolated word recognition experiments both in normal-hearing and deaf subject are presented, showing a promising word accuracy of 92% on average.

Control simulation of a six DOF parallel-serial robot for femur fracture reduction

Abstract: In femur fracture surgeries, medical personnel are exposed to large amount of X-ray radiation, which is harmful to human health. Robot-assisted fracture reduction of the femur is believed to be a good way to increase surgery accuracy and increase surgical efficiency. A parallel-serial surgical robot has been developed, named Dcros by the authors for such applications. This paper introduces the motion control of the robot and its control simulation. In motion control, we describe the structure of the robot and propose three angles defining the end-effectors orientation in 3D space and two Cartesian coordinates, one of which is for surgeons to input the end-effectors positions and define its orientations and the other is used to control motors for end-effectors movement. Determination of trajectory, translation velocities and angular velocities are also presented. In the simulation section, the snapshots of the simulation animation of the end-effectors motion are demonstrated by the MATLAB software and the software interfaces, motors displacements and velocities are shown as well.

A practical approach to encourage students participation in asynchronous online discussions based on expectancy theory

Abstract: With the popularity of computers and the Internet, the Internet learning mechanism has become a development trend of Internet applications, and learners can find the course resources of learning on the Internet. However, students generally lack of the intention to use e-learning platform for learning in current e-learning environment. Therefore, this research attempted to adopt the curriculum reward mechanism to encourage learners to participate in asynchronous online discussion platform based on expectancy theory. Through experiment, the results found that learners will enhance the frequencies of course discussion and actively interact with e-learning platform when e-learning platform integrates the curriculum reward mechanism into learning activities.

Associated Pagerank: Improved pagerank measured by frequent term sets

Abstract: Web search engines encounter many new challenges while the amount of information on the web increases rapidly. Web documents have been a main resource for various purposes, and people rely on search engines to retrieve the desired documents. This paper proposes an associated pagerank algorithm for search engines to feedback quality results by scoring the relevance of web documents. The modified Pagerank algorithm increases the degree of relevance than the original one, and decreases the query time efforts of topic-sensitive pagerank.

Camera control based on rigid body dynamics for virtual environments

Abstract: Desktop Virtual Environments (VEs) are an attractive choice for low-cost virtual reality systems. However, the level of virtual presence — the subjective sensation of perceiving oneself immersed within an environment — that desktop VEs offer is lower than immersive ones. There exist approaches that try to reduce the gap between the level of presence in these two types of VEs. For instance, to improve the interaction aspect by providing an environment that supports physically based behavior or to display high quality graphics that increases the overall scene realism. Most of these approaches have been employed in the design of desktop VEs, but often lacked a formal evaluation of their real impact on the level of presence afforded. This paper presents our work and research findings on developing a model to control camera travel based on rigid body dynamics. A physics engine simulates the dynamics involved in altering the cameras physical parameters — such as forces, torques, tensor of inertia — which, in turn, controls viewpoint orientation and locomotion. Our aim was twofold: to propose a camera whose movement behaviors were easy to program, and; to engage users of a desktop VE in a richer interaction experience capable of raising their level of presence. We designed an experimental study with a group of volunteers and measured their performance in controlling the camera as well as their reported virtual presence using the Witmer and Singers Presence Questionnaire.

Java based architecture for grid applications

Abstract: Environments that integrate network computer into global computing resources have been studied since the development of Internet. In order to provide a platform independent approach to high-performance network computing, several Java-based implementations have been developed. Java overcomes the issue of maintaining different binary codes, multiple execution environments, and complex architectures. It offers the basic infrastructure to integrate computers resources connected to Internet into a distributed computational resource and allows parallel applications execution on different O.S. environment. In this paper we discuss the design and implementation of a network computing prototype system based on Java technology. The proposed multi level architecture uses the Agent paradigm to manage resources and to develop a user friendly interface to share resources in the grid.

Independent Component Automatic Clustering and its application on multi-trails imaginary hand movement related EEG

Abstract: How to extract task-relevant components from spontaneous electroencephalogram background is an open problem in EEG signal analysis. An Independent Component Automatic Clustering (ICAC) method, which combined Independent Component Analysis (ICA) with automatic clustering, is developed in this paper. In ICAC, the ICA decomposed components were grouped into several clusters and sorted automatically. A majority of task-relevant components could be grouped into one cluster and be recognized easily, which can compensate the traditional ICA limitation of component sorting without any task specialized orders. We adopted this method on multi trails EEG signals during imaginary hand movement, results showed that ICAC can automatically extract task-relevant component and increase the Fisher Criterion (FC) separability significantly. Furthermore, we show that the residual mutual information between task-relevant components is not useless as previously regarded but very useful on components recognition.

Numerical input techniques for immersive virtual environments

Abstract: So far, in the literature, there exist only a few techniques for text input and none specifically for numeric input in immersive virtual environments Initially, we evaluated two techniques for numerical input, one employing whole hand gloves gestures and a second employing Pinch gloves While the first technique was proper only for small numbers and for limited use, the second technique performed well in all cases The Pinch glove technique was revised to allow for hand tracking and re-evaluated with a larger group of users Statistical analysis showed that the technique is promising and input rate is comparable to other input techniques

An Artificial Immune Network approach for Pinyin-to-character conversion

Abstract: This paper proposes a novel approach based on Artificial Immune Network for dealing with the task of Pinyin-to-character (PTC) conversion. The researches in recent years have nearly indicated that the sparse data problem and the independent identical distribution (iid.) assumption are two main difficulties of improving the PTC performance, and these two problems widely exist in the supervised learning methods. This paper presents an online learning approach to overcome the above problems. This model has a kind of ability of adaptively adjustment by using the feedback information, and in this model, the discriminative function gives the partial ordering relation of each immune chain so as to implement the partial perception online learning. The experiments show that our PTC conversion method based on the online learning technology can achieve a better performance than the n-gram language model, and this kind of improvement is hardly acquired by the classical supervised learning methods.