Tasks In Virtual Environment Research Articles

Design of a Wearable Fingertip Haptic Device for Remote Palpation: Characterisation and Interface with a Virtual Environment.

This paper presents the development of a wearable Fingertip Haptic Device (FHD) that can provide cutaneous feedback via a Variable Compliance Platform (VCP). The FHD includes an inertial measurement unit, which tracks the motion of the user’s finger while its haptic functionality relies on two parameters: pressure in the VCP and its linear displacement towards the fingertip. The combination of these two features results in various conditions of the FHD, which emulate the remote object or surface stiffness properties. Such a device can be used in tele-operation, including virtual reality applications, where rendering the level of stiffness of different physical or virtual materials could provide a more realistic haptic perception to the user. The FHD stiffness representation is characterised in terms of resulting pressure and force applied to the fingertip created through the relationship of the two functional parameters – pressure and displacement of the VCP. The FHD was tested in a series of user studies to assess its potential to create a user perception of the object’s variable stiffness. The viability of the FHD as a haptic device has been further confirmed by interfacing the users with a virtual environment. The developed virtual environment task required the users to follow a virtual path, identify objects of different hardness on the path and navigate away from “no-go” zones. The task was performed with and without the use of the variable compliance on the FHD. The results showed improved performance with the presence of the variable compliance provided by the FHD in all assessed categories and particularly in the ability to identify correctly between objects of different hardness.

A Virtual Object-Location Task for Children: Gender and Videogame Experience Influence Navigation; Age Impacts Memory and Completion Time.

The use of virtual reality-based tasks for studying memory has increased considerably. Most of the studies that have looked at child population factors that influence performance on such tasks have been focused on cognitive variables. However, little attention has been paid to the impact of non-cognitive skills. In the present paper, we tested 52 typically-developing children aged 5–12 years in a virtual object-location task. The task assessed their spatial short-term memory for the location of three objects in a virtual city. The virtual task environment was presented using a 3D application consisting of a 120″ stereoscopic screen and a gamepad interface. Measures of learning and displacement indicators in the virtual environment, 3D perception, satisfaction, and usability were obtained. We assessed the children’s videogame experience, their visuospatial span, their ability to build blocks, and emotional and behavioral outcomes. The results indicate that learning improved with age. Significant effects on the speed of navigation were found favoring boys and those more experienced with videogames. Visuospatial skills correlated mainly with ability to recall object positions, but the correlation was weak. Longer paths were related with higher scores of withdrawal behavior, attention problems, and a lower visuospatial span. Aggressiveness and experience with the device used for interaction were related with faster navigation. However, the correlations indicated only weak associations among these variables.

Feasibility, safety, acceptability, and functional outcomes of playing Nintendo Wii Fit Plus\u2122 for frail elderly: study protocol for a feasibility trial

BackgroundFrailty can be defined as a medical syndrome with multiple causes and contributors, characterized by diminished strength and endurance and reduced physiological function that increases the vulnerability to develop functional dependency and/or death. Studies have shown that the most commonly studied exercise protocol for frail older adults is the multimodal training. Interactive video games (IVGs) involve tasks in virtual environments that combine physical and cognitive demands in an attractive and challenging way. The aim of this study will be to evaluate the feasibility, safety, acceptability, and functional outcomes of playing Nintendo Wii Fit PlusTM (NWFP) for frail older adults.Methods/designThe study is a randomized controlled, parallel group, feasibility trial. Participants will be randomly assigned to the experimental group (EG) and control group (CG). The EG will participate in 14 training sessions, each lasting 50 min, twice a week. In each training session, the participants will play five games, with three attempts at each game. The first attempt will be performed with the assistance of a physical therapist to correct the movements and posture of the patients and subsequent attempts will be performed independently. Scores achieved in the games will be recorded. The participants will be evaluated by a blinded physical therapist at three moments: before and after intervention and 30 days after the end of the intervention (follow-up). We will assess the feasibility, acceptability, safety, and clinical outcomes (postural control, gait, cognition, quality of life, mood, and fear of falling).DiscussionDue to the deficiencies in multiple systems, studies have shown that multimodal interventions including motor-cognitive stimulation can improve the mobility of frail elderly adults. IVGs, among them the NWFP, are considered as a multimodal motor-cognitive intervention that can potentially improve motor and cognitive functions in the frail elderly. However, there is still no evidence in the literature that proves the feasibility, safety, acceptability, and functional outcomes of this intervention in frail elderly individuals.Trial registrationBrazilian Registry of Clinical Trials (RBR-823rst). World Health Organization Trial Registration Data Set (Additional file 1).

Manipulating the fidelity of lower extremity visual feedback to identify obstacle negotiation strategies in immersive virtual reality.

The ability to successfully navigate obstacles in our environment requires integration of visual information about the environment with estimates of our body's state. Previous studies have used partial occlusion of the visual field to explore how information about the body and impending obstacles are integrated to mediate a successful clearance strategy. However, because these manipulations often remove information about both the body and obstacle, it remains to be seen how information about the lower extremities alone is utilized during obstacle crossing. Here, we used an immersive virtual reality (VR) interface to explore how visual feedback of the lower extremities influences obstacle crossing performance. Participants wore a head-mounted display while walking on treadmill and were instructed to step over obstacles in a virtual corridor in four different feedback trials. The trials involved: (1) No visual feedback of the lower extremities, (2) an endpoint-only model, (3) a link-segment model, and (4) a volumetric multi-segment model. We found that the volumetric model improved success rate, placed their trailing foot before crossing and leading foot after crossing more consistently, and placed their leading foot closer to the obstacle after crossing compared to no model. This knowledge is critical for the design of obstacle negotiation tasks in immersive virtual environments as it may provide information about the fidelity necessary to reproduce ecologically valid practice environments.

Expanding Clinical Assessment for Traumatic Brain Injury and Comorbid Post-Traumatic Stress Disorder: A Retrospective Analysis of Virtual Environment Tasks in the Computer-Assisted Rehabilitation Environment.

The objective of this study was to determine whether physical performance during virtual environment (VE) tasks in the Computer-Assisted Rehabilitation Environment (CAREN) could differentiate between service members (SMs) with a history of traumatic brain injury (TBI) with and without comorbid post-traumatic stress disorder (PTSD). Data were obtained by independent review of clinical notes, objective outcomes, and validated questionnaires from 214 SMs (208 males) with a history of TBI assessed in the CAREN from 2010 to 2015. Three preliminary VEs acclimatized patients to the CAREN: Balance Balls, weight shifting on a static platform (timed); Balance Cubes, step shifting with and without platform motion (timed); and Continuous Road, flat ambulation (self-selected speed). Multiple regression analyses revealed that patients with comorbid TBI-PTSD were significantly slower in completing the VE tasks than patients without PTSD. Logistic regression showed that the Balance Cubes VE without platform motion significantly predicted diagnostic category (i.e., no PTSD vs. comorbid PTSD). In conclusion, in SMs with a history of TBI, physical performance on the CAREN effectively distinguished those with comorbid PTSD, as their performance was significantly slower than SMs without PTSD. These results portray the potential of the CAREN as a novel assessment tool in SMs with a history of TBI.

A visual salience model for wayfinding in 3D virtual urban environments

The study develops a modeling framework to quantify the saliency of individual buildings and to visualize them accordingly in a virtual 3D urban environment for wayfinding. Based on the cognitive characteristics of wayfinding behaviors and considering the relationships among pathfinder, buildings, and local context of the urban environment, this study defines and distinguishes two types of variables related to the saliency of a building, the global salience variables and the local salience variables. Then an adaptive weight distribution method is developed to determine the weight for each variable. Global salience is estimated in the context of a broader urban space, while local salience is estimated in the local region. Finally, a synthesized salience model is constructed by integrating the global and local salience values with consideration of the visibility factor. The salience values are used to identify most salient landmarks in each scene on the path of wayfinding. In the implemented prototype, 3D visualization is made for each scene showing buildings with varying levels of details according to their salience values. This study contributes to the research on intelligent 3D navigation systems by providing effective visual guidance for wayfinding tasks in virtual urban environments.

Poor sleep quality affects spatial orientation in virtual environments

Sleep is well known to have a significant impact on learning and memory. Specifically, studies adopting an experimentally induced sleep loss protocol in healthy individuals have provided evidence that the consolidation of spatial memories, as acquired through navigating and orienteering in spatial surroundings, is negatively affected by total sleep loss. Here, we used both objective and subjective measures to characterize individuals' quality of sleep, and grouped participants into either a poor (insomnia-like) or normal (control) sleep quality group. We asked participants to solve a wayfinding task in a virtual environment, and scored their performance by measuring the time spent to reach a target location and the number of wayfinding errors made while navigating. We found that participants with poor sleep quality were slower and more error-prone than controls in solving the task. These findings provide novel evidence that pre-existing sleep deficiencies in otherwise healthy individuals affects negatively the ability to learn novel routes, and suggest that sleep quality should be accounted for among healthy individuals performing experimental spatial orientation tasks in virtual environments.

Depth discrimination of constant angular size stimuli in action space: role of accommodation and convergence cues.

In our daily life experience, the angular size of an object correlates with its distance from the observer, provided that the physical size of the object remains constant. In this work, we investigated depth perception in action space (i.e., beyond the arm reach), while keeping the angular size of the target object constant. This was achieved by increasing the physical size of the target object as its distance to the observer increased. To the best of our knowledge, this is the first time that a similar protocol has been tested in action space, for distances to the observer ranging from 1.4–2.4 m. We replicated the task in virtual and real environments and we found that the performance was significantly different between the two environments. In the real environment, all participants perceived the depth of the target object precisely. Whereas, in virtual reality (VR) the responses were significantly less precise, although, still above chance level in 16 of the 20 observers. The difference in the discriminability of the stimuli was likely due to different contributions of the convergence and the accommodation cues in the two environments. The values of Weber fractions estimated in our study were compared to those reported in previous studies in peripersonal and action space.

Changing perspective: The role of vestibular signals

Social interactions depend on mechanisms such as the ability to take another person's viewpoint, i.e. visuo-spatial perspective taking. However, little is known about the sensorimotor mechanisms underpinning perspective taking. Because vestibular signals play roles in mental rotation and spatial cognition tasks and because damage to the vestibular cortex can disturb egocentric perspective, vestibular signals stand as important candidates for the sensorimotor foundations of perspective taking. Yet, no study merged natural full-body vestibular stimulations and explicit visuo-spatial perspective taking tasks in virtual environments. In Experiment 1, we combined natural vestibular stimulation on a rotatory chair with virtual reality to test how vestibular signals are processed to simulate the viewpoint of a distant avatar. While they were rotated, participants tossed a ball to a virtual character from the viewpoint of a distant avatar. Our results showed that vestibular signals influence perspective taking in a direction-specific way: participants were faster when their physical body rotated in the same direction as the mental rotation needed to take the avatar's viewpoint. In Experiment 2, participants realized 3D object mental rotations, which did not involve perspective taking, during the same whole-body vestibular stimulation. Our results demonstrated that vestibular stimulation did not affect 3D object mental rotations. Altogether, these data indicate that vestibular signals have a direction-specific influence on visuo-spatial perspective taking (self-centered mental imagery), but not a general effect on mental imagery. Findings from this study suggest that vestibular signals contribute to one of the most crucial mechanisms of social cognition: understanding others’ actions.

Virtual Environments for People who Are Visually Impaired Integrated into an Orientation and Mobility Program

Introduction The BlindAid, a virtual system developed for orientation and mobility (O&M) training of people who are blind or have low vision, allows interaction with different virtual components (structures and objects) via auditory and haptic feedback. This research examined if and how the BlindAid that was integrated within an O&M training program could be of help when teaching those who are blind or visually impaired to develop O&M skills. Methods Using qualitative and quantitative methods, this research focused on 16 participants during their O&M course, and studied virtual environment exploration and orientation tasks in virtual environments. Results The encouraging results of the current study indicate the potential strengths of the BlindAid system as an O&M training device for visually impaired people. Discussion Follow-up research evaluating transference of knowledge from virtual environments to real spaces could contribute to O&M training for people who are visually impaired. Implications for practitioners BlindAid could play a central role in three potential applications: a training simulator for O&M, a diagnostic tool for O&M specialists to track and observe participants’ spatial behavior, and a technique for advanced exploration of unknown spaces.

New Exoskeleton Arm Concept Design And Actuation For Haptic Interaction With Virtual Objects

Abstract In the work presented in this paper the conceptual design and actuation of one new exoskeleton of the upper limb is presented. The device is designed for application where both motion tracking and force feedback are required, such as human interaction with virtual environment or rehabilitation tasks. The choice is presented of mechanical structure kinematical equivalent to the structure of the human arm. An actuation system is selected based on braided pneumatic muscle actuators. Antagonistic drive system for each joint is shown, using pulley and cable transmissions. Force/displacement diagrams are presented of two antagonistic acting muscles. Kinematics and dynamic estimations are performed of the system exoskeleton and upper limb. Selected parameters ensure in the antagonistic scheme joint torque regulation and human arm range of motion.

A seamless solution for 3D real-time interaction: design and evaluation

This paper aims to propose and evaluate a markerless solution for capturing hand movements in real time to allow 3D interactions in virtual environments (VEs). Tools such as keyboard and mice are not enough for interacting in 3D VE; current motion capture systems are expensive and require wearing equipment. We developed a solution to allow more natural interactions with objects and VE for navigation and manipulation tasks. We conducted an experimental study involving 20 participants. The goal was to realize object manipulation (moving, orientation, scaling) and navigation tasks in VE. We compared our solution (Microsoft Kinect-based) with data gloves and magnetic sensors (3DGloves) regarding two criteria: performance and acceptability. Results demonstrate similar performance (precision, execution time) but a better overall acceptability for our solution. Preferences of participants are mostly in favor of the 3DCam, mainly for the criteria of comfort, freedom of movement, and handiness. Our solution can be considered as a real alternative to conventional systems for object manipulation in virtual reality.

The Effect of Navigational Tools and Related Experience on Task Performance in a Virtual Environment

One of the problems associated with using virtual environments, for the purpose of training and/or assessment, is that the effect of navigational tools and related experience on performance is generally unknown. In this study, three separate types of navigational assistance were provided (1) a recommended path embedded in the environment, (2) the user’s trail embedded in the environment and (3) none (a control condition). Three levels of related experience were also considered: novice, intermediate, and advanced. The virtual environment task was a safety-hazard identification task in a virtual manufacturing facility – a task with both search and decision-making components. Both objective and subjective measures were employed; the objective measures were task time, task accuracy, and distance traveled within the environment, and the subjective measures were dimensions of workload, presence, and usability. Statistically significant differences were found between the navigation tools for task time, accuracy, and immersion (a dimension of presence). The results suggest that both the type of navigation tool and the level of experience influence performance.

Rehabilitation program integrating virtual environment to improve orientation and mobility skills for people who are blind

This paper presents the integration of a virtual environment (BlindAid) in an orientation and mobility rehabilitation program as a training aid for people who are blind. BlindAid allows the users to interact with different virtual structures and objects through auditory and haptic feedback. This research explores if and how use of the BlindAid in conjunction with a rehabilitation program can help people who are blind train themselves in familiar and unfamiliar spaces. The study, focused on nine participants who were congenitally, adventitiously, and newly blind, during their orientation and mobility rehabilitation program at the Carroll Center for the Blind (Newton, Massachusetts, USA). The research was implemented using virtual environment (VE) exploration tasks and orientation tasks in virtual environments and real spaces. The methodology encompassed both qualitative and quantitative methods, including interviews, a questionnaire, videotape recording, and user computer logs. The results demonstrated that the BlindAid training gave participants additional time to explore the virtual environment systematically. Secondly, it helped elucidate several issues concerning the potential strengths of the BlindAid system as a training aid for orientation and mobility for both adults and teenagers who are congenitally, adventitiously, and newly blind.

Assessing the Ability of a VR-Based Assembly Task Simulation to Evaluate PhysicalRisk Factors

Nowadays the process of workstation design tends to include assessment steps in a virtual environment (VE) to evaluate the ergonomic features. These approaches are cost-effective and convenient since working directly on the digital mock-up in a VE is preferable to constructing a real physical mock-up in a real environment (RE). This study aimed at understanding the ability of a VR-based assembly tasks simulator to evaluate physical risk factors in ergonomics. Sixteen subjects performed simplified assembly tasks in RE and VE. Motion of the upper body and five muscle electromyographic activities were recorded to compute normalized and averaged objective indicators of discomfort, that is, rapid upper limb assessment score, averaged muscle activations, and total task time. Rated perceived exertion (RPE) and a questionnaire were used as subjective indicators of discomfort. The timing regime and complexity of the assembly tasks were investigated as within-subject factors. The results revealed significant differences between measured indicators in RE and VE. While objective measures indicated lower activity and exposure in VE, the subjects experienced more discomfort than in RE. Fairly good correlation levels were found between RE and VE for six of the objective indicators. This study clearly demonstrates that ergonomic studies of assembly tasks using VR are still challenging. Indeed, objective and subjective measurements of discomfort that are usually used in ergonomics to minimize the risks of work-related musculoskeletal disorders development exhibit opposite trends in RE and VE. Nevertheless, the high level of correlation found during this study indicates that the VR-based simulator can be used for such assessments.

Designing and evaluating a workstation in real and virtual environment: toward virtual reality based ergonomic design sessions

This paper adresses the issue of properly designing a digital mock-up (DMU) to be used in an experiment comparing simulated assembly tasks in both real and virtual environments. Motivations and specifications relative to the experiment are reported, and the design process of the DMU is described and illustrated. Recommendations are proposed with a particular focus on specificities relative to the use of a DMU as a support for both manufacturing and virtual reality—3D visualisation and interaction. A subjective evaluation of Real (RE), Virtual (VE), and Virtual with Force Feedback (VEF) environments is provided. Results indicate a real sensory and difficulty gap between RE and VEF, whereas a smaller difference was observed between RE and VE. In further improvements of scale-1 (where the objects in VE have the same size as in the real environment), co-localized simulation using haptic devices are warranted to fill in this gap. Results also highlight the impact of cognition and sensory feedback on user’s feeling and presence sensation. Applications of such numerical designs are presented in the last section, especially focusing on collaborative design sessions. Virtual Reality based evaluation of newly designed workstations will be a way in the future to improve design and user learning processes.

Reorienting in Virtual 3D Environments: Do Adult Humans Use Principal Axes, Medial Axes or Local Geometry?

Studies have shown that animals, including humans, use the geometric properties of environments to orient. It has been proposed that orientation is accomplished primarily by encoding the principal axes (i.e., global geometry) of an environment. However, recent research has shown that animals use local information such as wall length and corner angles as well as local shape parameters (i.e., medial axes) to orient. The goal of the current study was to determine whether adult humans reorient according to global geometry based on principal axes or whether reliance is on local geometry such as wall length and sense information or medial axes. Using a virtual environment task, participants were trained to select a response box located at one of two geometrically identical corners within a featureless rectangular-shaped environment. Participants were subsequently tested in a transformed L-shaped environment that allowed for a dissociation of strategies based on principal axes, medial axes and local geometry. Results showed that participants relied primarily on a medial axes strategy to reorient in the L-shaped test environment. Importantly, the search behaviour of participants could not be explained by a principal axes-based strategy.

Gray and white matter correlates of navigational ability in humans.

Humans differ widely in their navigational abilities. Studies have shown that self-reports on navigational abilities are good predictors of performance on navigation tasks in real and virtual environments. The caudate nucleus and medial temporal lobe regions have been suggested to subserve different navigational strategies. The ability to use different strategies might underlie navigational ability differences. This study examines the anatomical correlates of self-reported navigational ability in both gray and white matter. Local gray matter volume was compared between a group (N = 134) of good and bad navigators using voxel-based morphometry (VBM), as well as regional volumes. To compare between good and bad navigators, we also measured white matter anatomy using diffusion tensor imaging (DTI) and looked at fractional anisotropy (FA) values. We observed a trend toward higher local GM volume in right anterior parahippocampal/rhinal cortex for good versus bad navigators. Good male navigators showed significantly higher local GM volume in right hippocampus than bad male navigators. Conversely, bad navigators showed increased FA values in the internal capsule, the white matter bundle closest to the caudate nucleus and a trend toward higher local GM volume in the caudate nucleus. Furthermore, caudate nucleus regional volume correlated negatively with navigational ability. These convergent findings across imaging modalities are in line with findings showing that the caudate nucleus and the medial temporal lobes are involved in different wayfinding strategies. Our study is the first to show a link between self-reported large-scale navigational abilities and different measures of brain anatomy.

SimCrane 3D+: A crane simulator with kinesthetic and stereoscopic vision

Crane operation training using virtual crane simulators has been introduced in the last decade. It can reduce the costs associated with renting actual cranes and enables operator training for a range of tasks in virtual environment. However, a critical drawback common to most existing simulators is a lack of realistic simulation for the depth perception, which usually relies on stereoscopic vision and head motion to increase the precision of depth perception. This research aimed at adopting kinesthetic vision and stereoscopic vision into a virtual crane simulator to increase its training effectiveness. Kinesthetic vision generates corrected perspective images based on the head position of the viewer. Stereoscopic vision is to generate separated images for left and right eyes respectively. A crane simulator known as SimCrane 3D+ was developed and implemented to achieve the goal. We performed user tests to evaluate the proposed system by both subjective and objective factors. The results showed that the system provide better simulation for depth perception. Operators increase their confidences in the tests. They also reported using SimCrane 3D+ is more intuitive than the simulator without stereoscopic or kinesthetic visions.

Collaborative Versus Individual Learning Experiences in Virtual Education: The Effects of a Time Variable

In this study we analyzed a time effect variable on the performance of collaborative versus individual tasks. Thirty-one postgraduate students carried out two online collaborative learning tasks and two online individual tasks as part of a university course. The results of an ANOVA did not show significant effects of time or task type variables, although the effect of interaction was significant. At the beginning of the course (T1) the students’ performance was significantly higher in the collaborative tasks, while at the end of the course (T2) this trend was reversed, with the students’ performance in individual tasks being significantly higher than in the collaborative tasks. The results suggest implications for when to incorporate collaborative learning tasks in virtual learning environments.