Virtual Feedback Research Articles

Non-Immersive, Virtual Reality Mirror Visual Feedback for Treatment of Persistent Idiopathic Facial Pain

Dear Editor, This letter describes a preliminary proof-of-concept test of a novel, non-invasive, virtual reality mirror visual feedback (VRMVF) therapy for persistent idiopathic facial pain. Persistent idiopathic face pain (PIFP) shares some characteristics with complex regional pain syndrome (CRPS) type 1: The pain develops after a relatively minor noxious event; is not associated with a specific nerve injury; and results in constant, severe, and often disabling pain. Patients with both conditions may develop allodynia and/or thermal sensitivity, and may limit movement of the affected part to minimize pain. Mirror visualization feedback (MVF) is one approach used for CRPS that might also prove useful in treating PIFP. In 1996, Ramachandran discovered that MVF therapy might mitigate phantom limb pain in amputees [1]. Attempts to expand on this use of MVF have included efforts to treat phantom limb pain, fibromyalgia [2] CRPS [3] and facial pain [4] both in the original format and using virtual reality (VR) [5–7]. We theorized that the similarities between CRPS and PIFP might make a MVF therapy that relies on painless touch effective in treating PIFP as well. In our method, a digital model (or “avatar”) represents the patients head and neck, with the computer screen serving as the “mirror.” This method would allow the …

Suppressing nano-scale stick-slip motion by feedback

When a micro cantilever with a nano-scale tip is manipulated on a substrate with atomic-scale roughness, the periodic lateral frictional force and stochastic fluctuations may induce stick-slip motion of the cantilever tip, which greatly decreases the precision of the nano manipulation. This unwanted motion cannot be reduced by open-loop control especially when there exist parameter uncertainties in the system model, and thus needs to introduce feedback control. However, real-time feedback cannot be realized by the existing virtual reality virtual feedback techniques based on the position sensing capacity of the atomic force microscopy (AFM). To solve this problem, we propose a new method to design real-time feedback control based on the force sensing approach to compensate for the disturbances and thus reduce the stick-slip motion of the cantilever tip. Theoretical analysis and numerical simulations show that the controlled motion of the cantilever tip tracks the desired trajectory with much higher precision. Further investigation shows that our proposal is robust under various parameter uncertainties. Our study opens up new perspectives of real-time nano manipulation.

Virtual Feedback Error Learning by Means of Cascade Connection of an Inverse System

Virtual Feedback Error Learning by Means of Cascade Connection of an Inverse System

Rendering Virtual Tumors in Real Tissue Mock-Ups Using Haptic Augmented Reality.

Haptic augmented reality (AR) is an emerging research area, which targets the modulation of haptic properties of real objects by means of virtual feedback. In our research, we explore the feasibility of using this technology for medical training systems. As a possible demonstration example, we currently examine the use of augmentation in the context of breast tumor palpation. The key idea in our prototype system is to augment the real feedback of a silicone breast mock-up with simulated forces stemming from virtual tumors. In this paper, we introduce and evaluate the underlying algorithm to provide these force augmentations. This includes a method for the identification of the contact dynamics model via measurements on real sample objects. The performance of our augmentation is examined quantitatively as well as in a user study. Initial results show that the haptic feedback of indenting a real silicone tumor with a rod can be approximated reasonably well with our algorithm. The advantage of such an augmentation approach over physical training models is the ability to create a nearly infinite variety of palpable findings.

Developing Preceptors through Virtual Communities and Networks: Experiences from a Pilot Project

Supporting preceptors is critical to the expansion of experiential learning opportunities for the pharmacy profession. Informal learning opportunities within communities of practitioners are important for hospital preceptors. However, such communities may be limited by geographic separation of preceptors from peers, faculty members, and supports within the pharmacy services department. To use computer-mediated conferencing to create a sense of community among preceptors, specifically by using this medium to provide initial development of and continuing support for preceptors, and to examine preceptors' satisfaction with this approach. Thirty-nine preceptors who had completed a day-long face-to-face preceptor development workshop and who were supervising students in 1 of 2 specific rotation blocks were invited to participate in the study. The pharmacists used computer-mediated conferencing to meet for virtual networking about specific topics. They met once before the student rotation to receive instructions about the technology and to discuss student orientation and scheduling, and 3 times during the student rotation for open discussion of specific topics. Evaluation and feedback were solicited by means of an electronic survey and virtual (i.e., computer-based) feedback sessions with an independent facilitator. The response rate was 66% (26/39) for the electronic survey, but only 15% (6/39) for the virtual feedback sessions. All of the respondents were experienced preceptors, but for 92% (22/24), this was their first experience with computer-mediated conferencing. Overall, the sessions had a positive reception, and participants found it useful to share information and experiences with other preceptors. The main challenges were related to the technology, perceived lack of support for their participation in the sessions, and inconvenience related to the timing of sessions. Computer-mediated conferencing allowed preceptors to learn from and to support each other despite geographic distance. The participants felt that these sessions encouraged them to serve as preceptors regularly. Such encouragement could contribute to the retention of preceptors, which is important to the expansion of experiential learning.

Stability Analysis and Performance Evaluation of a Feedback Controller for Local Control of Sound

This paper investigates the performance and stability of a virtual microphone feedback controller for local control of sound through theoretical analysis and simulations. A novel method to design a stable feedback controller for the local control system is also presented in this paper. The local control system is designed to attenuate a broadband disturbance at a point near the listener’s ear, i.e. the virtual microphone, rather than at the control microphone, i.e. the physical microphone. The results showed that if a good performance was to be achieved the controller would be unstable. This is because the magnitude of the response of the virtual plant is lower than that of the physical plant. The feedback controller in this work is designed to minimize the noise at the virtual microphone, with a virtual plant response used in the performance objective. However the physical plant is used in the stability constraint. Therefore there is a trade-off between the performance and controller stability.

Does Virtual Reality Enhance Exercise Performance, Enjoyment, and Dissociation? An Exploratory Study on a Stationary Bike Apparatus

The present study aimed at testing the general assumption that virtual reality can enhance the experience of exercising. More specifically, we tested the effects of sensory input (music and video feedback) during physical training on performance, enjoyment, and attentional focus by means of a computerized ergometer coupled with VR software. Twelve university students participated in the study. The experimental procedure consisted in a 2 × 3 × 4 mixed design, with two types of feedback (video feedback vs. video feedback and music), three course phases (e.g., flat, uphill, and downhill) and four sessions (task repetition). The virtual feedback was a video film of the course that participants had to complete. Video display speed was proportional to the participant's pedaling speed. Force feedback, applied to the real bicycle wheel, was proportional to the instantaneous course slope. The results showed a positive effect of task repetition on participants' performance only when video feedback was associated with listening to music. In an attempt to objectively assess attentional focus, we analyzed participants' gaze orientation. Gaze analysis showed a reduction in the time spent gazing at video feedback across sessions. Associating video feedback with freely chosen music led to a differential use of video feedback as a function of exercise intensity. Finally, sensory stimulation appeared to have a dissociative role on participants' attentional focus during exercise, but adding music listening to video feedback appears to be necessary to maintain (long term) the participants' commitment to the task. The results are discussed in terms of the functional status of sensory stimulation during exercise, and its interactions with exercise intensity, participants' performance, and attentional focus. They also suggest that gaze analysis is one promising way to access attention allocation and its relationships with performance.

Robot-Aided Upper-Limb Rehabilitation Based on Motor Imagery EEG

Stroke is a leading cause of disability worldwide. In this paper, a novel robot-assisted rehabilitation system based on motor imagery electroencephalography (EEG) is developed for regular training of neurological rehabilitation for upper limb stroke patients. Firstly, three-dimensional animation was used to guide the patient image the upper limb movement and EEG signals were acquired by EEG amplifier. Secondly, eigenvectors were extracted by harmonic wavelet transform (HWT) and linear discriminant analysis (LDA) classifier was utilized to classify the pattern of the left and right upper limb motor imagery EEG signals. Finally, PC triggered the upper limb rehabilitation robot to perform motor therapy and gave the virtual feedback. Using this robot-assisted upper limb rehabilitation system, the patient's EEG of upper limb movement imagination is translated to control rehabilitation robot directly. Consequently, the proposed rehabilitation system can fully explore the patient's motivation and attention and directly facilitate upper limb post-stroke rehabilitation therapy. Experimental results on unimpaired participants were presented to demonstrate the feasibility of the rehabilitation system. Combining robot-assisted training with motor imagery-based BCI will make future rehabilitation therapy more effective. Clinical testing is still required for further proving this assumption.

Incorporating the e-HIM Virtual Lab into the Health Information Administration Professional Practice Experience

This article will highlight the experiences of two baccalaureate Health Information Administration (HIA) programs in the adoption of the American Health Information Management Association’s (AHIMA) e-HIM Virtual Laboratory (Virtual Lab) into the Professional Practice Experience (PPE). Information describing the implementation of the Virtual Lab, issues encountered, and subsequent feedback from students and faculty regarding this new technology is provided.

User-based evaluation of data-driven haptic rendering

In this article, the data-driven haptic rendering approach presented in our earlier work is assessed. The approach relies on recordings from real objects from which a data-driven model is derived that captures the haptic properties of the object. We conducted two studies. In the first study, the Just Noticeable Difference (JND) for small forces, as encountered in our set-up, was determined. JNDs were obtained both for active and passive user interaction. A conservative threshold curve was derived that was then used to guide the model generation in the second study. The second study examined the achievable rendering fidelity for two objects with different stiffnesses. Subjects directly compared data-driven virtual feedback with the real objects. Results indicated that it is crucial to include dynamic material effects to achieve haptic feedback that cannot be distinguished from real objects. Results also showed that the fidelity is considerably decreased for stiffer objects due to limits of the display hardware.

Ask Us Anytime: Creating a Searchable FAQ Using Email and Chat Reference Transcripts

Users are increasingly expecting services to be available outside traditional venues and time frames. Clearly, not all library functions and services can be performed all the time, but a Frequently Asked Question (FAQ) tool is one function that can be. Librarians at Notre Dame decided to create a searchable FAQ database as a method to efficiently reach users at their time and point of need and as a way to provide instant, virtual feedback to common questions. The content for the FAQ database was derived from the analysis of over 3000 chat and email questions collected over the course of three years’ use of Docutek, an email and chat reference software. The process of coding the questions as well as the technological solutions employed to create a searchable database of frequently asked questions is described. A link to the FAQ appears on the ND Libraries Ask-A-Librarian page and has already seen much use.

Effects of 3D Virtual Haptics Force Feedback on Brand Personality Perception: The Mediating Role of Physical Presence in Advergames

Effects of 3D Virtual Haptics Force Feedback on Brand Personality Perception: The Mediating Role of Physical Presence in Advergames

Impact of Motivating Language on Team Creative Performance

An abundance of previous theories and empirical studies have verified that leadership styles indeed can influence members' creativity and effectiveness in both traditional team settings and in a virtual context. Moreover, past research has also indicated that leaders can build relationships among team members and increase mutual trust due to the face to face interaction made possible in a traditional office environment. However, there is little empirical work that articulates how leaders behave and motivate their members in a virtual context. This study employed an experimental design with 50 undergraduate juniors who acted as the team members and 23 Executive MBA students who acted as the team leaders. The main goal was to study the impact of leaders' motivating language (i.e., empathetic, direction-giving, and mixed usage) on team members' creative performance. Key findings indicate that there are slightly significant differences between three kinds of motivating language approaches. The study shows that leaders who give virtual team members feedback via written communication that is both directional and empathetic are perceived as more effective and lead to better performance.

Sensorimotor training in virtual reality: A review

Recent experimental evidence suggests that rapid advancement of virtual reality (VR) technologies has great potential for the development of novel strategies for sensorimotor training in neurorehabilitation. We discuss what the adaptive and engaging virtual environments can provide for massive and intensive sensorimotor stimulation needed to induce brain reorganization.Second, discrepancies between the veridical and virtual feedback can be introduced in VR to facilitate activation of targeted brain networks, which in turn can potentially speed up the recovery process. Here we review the existing experimental evidence regarding the beneficial effects of training in virtual environments on the recovery of function in the areas of gait,upper extremity function and balance, in various patient populations. We also discuss possible mechanisms underlying these effects. We feel that future research in the area of virtual rehabilitation should follow several important paths. Imaging studies to evaluate the effects of sensory manipulation on brain activation patterns and the effect of various training parameters on long term changes in brain function are needed to guide future clinical inquiry. Larger clinical studies are also needed to establish the efficacy of sensorimotor rehabilitation using VR in various clinical populations and most importantly, to identify VR training parameters that are associated with optimal transfer to real-world functional improvements.

Sliding mode control for uncertain neutral system with time‐delays

PurposeThe purpose of this paper is to find an appropriate sliding mode control strategy for neutral systems with time‐delays in the presence of unmatched parameter uncertainties and external disturbance.Design/methodology/approachOwing to the complexity of uncertain neutral time‐delay systems, some conclusions for system stability and stabilization are complicated non‐linear matrix inequality (NLMI). Through virtual state feedback control, a sliding mode controller is designed to guarantee state trajectories from any initial condition are attracted to the sliding mode plane in a finite time and remain there for all subsequent time, which can avoid the complicated NLMI. Furthermore, a delay‐independent sufficient condition for the design of robust stable sliding mode plane is obtained in term of LMI.FindingsThe sliding mode controller for uncertain neutral time‐delay systems is designed and a delay‐independent sufficient condition for the design of robust stable sliding mode plane is obtained.Research limitations/implicationsThe main limitations are that external disturbance must meet matched condition.Practical implicationsA useful control strategy for uncertain neutral systems with time‐delays.Originality/valueThe virtual state feedback control is designed so to avoid the complicated NLMI.

Training With Virtual Visual Feedback to Alleviate Phantom Limb Pain

Background. Performing phantom movements with visual virtual feedback, or mirror therapy, is a promising treatment avenue to alleviate phantom limb pain. However the effectiveness of this approach appears to vary from one patient to another. Objective. To assess the individual response to training with visual virtual feedback and to explore factors influencing the response to that approach. Methods. Eight male participants with phantom limb pain (PLP) resulting from either a traumatic upper limb amputation or a brachial plexus avulsion participated in this single case multiple baseline study. Training was performed 2 times per week for 8 weeks where a virtual image of a missing limb performing different movements was presented and the participant was asked to follow the movements with his phantom limb. Results. Patients reported an average 38% decrease in background pain on a visual analog scale (VAS), with 5 patients out of 8 reporting a reduction greater than 30%. This decrease in pain was maintained at 4 weeks postintervention in 4 of the 5 participants. No significant relationship was found between the long-term pain relief and the duration of the deafferentation or with the immediate pain relief during exposure to the feedback. Conclusions. These results support the use of training with virtual feedback to alleviate phantom limb pain. Our observations suggest that between-participant differences in the effectiveness of the treatment might be related more to a difference in the susceptibility to the virtual visual feedback, than to factors related to the lesion, such as the duration of the deafferentation.

Virtual Reality and Physical Activity: Attentional and Behavioral Aspects

The present study tested the effects of sensorial inputs on performance and attentional focus during physical training on a computerized ergometer. 18 students were involved in this study. The experimental procedure consisted in a 3x3x4 mixed design, with 3 practice modalities (virtual feedback, virtual feedback and music, virtual and heart rate feedback) 3 course phases (e.g., flat, uphill, downhill) and 4 sessions. The virtual feedback was a video film of the course subjects had to complete. Video display speed was proportional to the subject's pedalling speed. Results show a training effect on the subjects' overall performance and a reduction of the time spent gazing at video feedback across sessions. The results are discussed in terms of the functional status of sensorial stimulation and its interactions with exercise intensity and subject performance.

A tracking system with space virtual feedback

In this paper, a tracking system with space virtual feedback (SVF) is presented. The whole tracking system is closed by the space virtual feedback line that is the line of sight (LOS), but the parts in the system, such as the tracking subsystem and the servo subsystem, are in the state of open-loop. Because the SVF tracking model is used, the correcting loops can be removed in this system architecture. So the tracking speed and accuracy of the system are greatly improved.

A novel high speed transport protocol based on explicit virtual load feedback

Since traditional TCP congestion control is ill-suited for high speed networks, designing a high speed replacement for TCP has become a challenge. From the simulations of some existing high speed protocols, we observe that these high speed protocols make the round-trip time bias problem and the multiple-bottleneck bias problem more serious than for standard TCP. To address these problems, we apply the population ecology theory to design a novel congestion control algorithm. By analogy, we treat the network flows as the species in nature, the sending rates of the flows as the population number, and the bottleneck bandwidth as the food resources. Then we extend the construction method of population ecology models to design a control model, and implement the corresponding end-to-end protocol with virtual load factor feedback, which is called Explicit Virtual Load Feedback TCP (EVLF-TCP). The virtual load factor is computed based on the information of the bandwidth, the aggregate incoming traffic and the queue length in routers, and then senders adjust the sending rate based on the virtual load factor. Theoretical analysis and simulation results validate that EVLF-TCP achieves high utilization, fair bandwidth allocation independent of round-trip time, and near-zero packet drops. These characteristics are desirable for high speed networks.

Robust control of uncertain time delay system: a novel sliding mode control design via LMI

The sliding mode control problem (SMC) is studied for a class of uncertain delay system in the presence of both parameter uncertainties and external disturbances. A novel virtual feedback control method is presented. Based on Lyapunov theory, sufficient conditions for design of the robust sliding mode plane are derived. Sliding mode controller based on reaching law concept is developed, which is to ensure system trajectories from any initial conditions asymptotically convergent to sliding mode plane. The global asymptotically stability of the closed-loop system is guaranteed. A numerical example with simulation results is given to illustrate the effectiveness of the methodology.