Gait parameters while walking in a head-mounted display virtual environment and the real world

Full-body motion tracking data was collected for six subjects during free walking. Each participant was asked to walk to a previously seen target under four experimental conditions: eyes closed within the real world, eyes closed wearing a head-mounted display (HMD), eyes open in the real world, and eyes open wearing a HMD. We report three gait parameters for each of these four conditions: stride length, walking velocity, and head-trunk angle. This data reveals that these gait parameters within a HMD virtual environment (VE) are different than those in the real world. A person wearing a HMD and backpack walks slower, and takes a shorter stride length than they do in a comparable real world condition. In addition, head-trunk angle while walking to a target on the ground plane is lowest when walking with eyes open in a HMD VE

Towards Naturalistic Interfaces of Virtual Reality Systems

Interaction plays a key role in achieving realistic experience in virtual reality (VR). Its realization depends on interpreting the intents of human motions to give inputs to VR systems. Thus, understanding human motion from the computational perspective is essential to the design of naturalistic interfaces for VR. This dissertation studied three types of human motions, including locomotion (walking), head motion and hand motion in the context of VR. For locomotion, the dissertation presented a machine learning approach for developing a mechanical repositioning technique based on a 1-D treadmill for interacting with a unique new large-scale projective display, called the Wide-Field Immersive Stereoscopic Environment (WISE). The usability of the proposed approach was assessed through a novel user study that asked participants to pursue a rolling ball at variable speed in a virtual scene. In addition, the dissertation studied the role of stereopsis in avoiding virtual obstacles while walking by asking participants to step over obstacles and gaps under both stereoscopic and non-stereoscopic viewing conditions in VR experiments. In terms of head motion, the dissertation presented a head gesture interface for interaction in VR that recognizes real-time head gestures on head-mounted displays (HMDs) using Cascaded Hidden Markov Models. Two experiments were conducted to evaluate the proposed approach. The first assessed its offline classification performance while the second estimated the latency of the algorithm to recognize head gestures. The dissertation also conducted a user study that investigated the effects of visual and control latency on teleoperation of a quadcopter using head motion tracked by a head-mounted display. As part of the study, a method for objectively estimating the end-to-end latency in HMDs was presented. For hand motion, the dissertation presented an approach that recognizes dynamic hand gestures to implement a hand gesture interface for VR based on a static head gesture recognition algorithm. The proposed algorithm was evaluated offline in terms of its classification performance. A user study was conducted to compare the performance and the usability of the head gesture interface, the hand gesture interface and a conventional gamepad interface for answering Yes/No questions in VR. Overall, the dissertation has two main contributions towards the improvement of naturalism of interaction in VR systems. Firstly, the interaction techniques presented in the dissertation can be directly integrated into existing VR systems offering more choices for interaction to end users of VR technology. Secondly, the results of the user studies of the presented VR interfaces in the dissertation also serve as guidelines to VR researchers and engineers for designing future VR systems

Walking with head-mounted virtual and augmented reality devices : effects on position control and gait biomechanics

What was once a science fiction fantasy, virtual reality (VR) technology has evolved and come a long way. Together with augmented reality (AR) technology, these simulations of an alternative environment have been incorporated into rehabilitation treatments. The introduction of head-mounted displays has made VR/AR devices more intuitive and compact, and no longer limited to upper-limb rehabilitation. However, there is still limited evidence supporting the use of VR and AR technology during locomotion, especially regarding the safety and efficacy relating to walking biomechanics. Therefore, the objective of this study is to explore the limitations of such technology through gait analysis. In this study, thirteen participants walked on a treadmill in normal, virtual and augmented versions of the laboratory environment. A series of spatiotemporal parameters and lower-limb joint angles were compared between conditions. The center of pressure (CoP) ellipse area (95% confidence ellipse) was significantly different between conditions (p = 0.002). Pairwise comparisons indicated a significantly greater CoP ellipse area for both the AR (p = 0.002) and VR (p = 0.005) conditions when compared to the normal laboratory condition. Furthermore, there was a significant difference in stride length (p0.082), except for maximum ankle plantarflexion (p = 0.001). These differences in CoP ellipse area indicate that users of head-mounted VR/AR devices had difficulty maintaining a stable position on the treadmill. Also, differences in the gait parameters suggest that users walked with an unusual gait pattern which could potentially affect the effectiveness of gait rehabilitation treatments. Based on these results, position guidance in the form of feedback and the use of specialized treadmills should be considered when using head-mounted VR/AR devices

Augmented reality system with application in physical rehabilitation

The aging phenomenon causes increased physiotherapy services requirements, with increased costs associated with long rehabilitation periods. Traditional rehabilitation methods rely on the subjective assessment of physiotherapists without supported training data. To overcome the shortcoming of traditional rehabilitation method and improve the efficiency of rehabilitation, AR (Augmented Reality) which represents a promissory technology that provides an immersive interaction with real and virtual objects is used. The AR devices may assure the capture body posture and scan the real environment that conducted to a growing number of AR applications focused on physical rehabilitation. In this MSc thesis, an AR platform used to materialize a physical rehabilitation plan for stroke patients is presented. Gait training is a significant part of physical rehabilitation for stroke patients. AR represents a promissory solution for training assessment providing information to the patients and physiotherapists about exercises to be done and the reached results. As part of MSc work an iOS application was developed in unity 3D platform. This application immersing patients in a mixed environment that combine real-world and virtual objects. The human computer interface is materialized by an iPhone as head-mounted 3D display and a set of wireless sensors for physiological and motion parameters measurement. The position and velocity of the patient are recorded by a smart carpet that includes capacitive sensors connected to a computation unit characterized by Wi-Fi communication capabilities. AR training scenario and the corresponding experimental results are part of the thesis.O envelhecimento causa um aumento das necessidades dos serviços de fisioterapia, com aumento dos custos associados a longos períodos de reabilitação. Os métodos tradicionais de reabilitação dependem da avaliação subjetiva de fisioterapeutas sem registo automatizado de dados de treino. Com o principal objetivo de superar os problemas do método tradicional e melhorar a eficiência da reabilitação, é utilizada a RA (Realidade Aumentada), que representa uma tecnologia promissora, que fornece uma interação imersiva com objetos reais e virtuais. Os dispositivos de RA são capazes de garantir uma postura correta do corpo de capturar e verificar o ambiente real, o que levou a um número crescente de aplicações de RA focados na reabilitação física. Neste projeto, é apresentada uma plataforma de RA, utilizada para materializar um plano de reabilitação física para pacientes que sofreram AVC. O treino de marcha é uma parte significativa da reabilitação física para pacientes com AVC. A RA apresenta-se como uma solução promissora para a avaliação do treino, fornecendo informações aos pacientes e aos profissionais de fisioterapia sobre os exercícios a serem realizados e os resultados alcançados. Como parte deste projeto, uma aplicação iOS foi desenvolvida na plataforma Unity 3D. Esta aplicação fornece aos pacientes um ambiente imersivo que combina objetos reais e virtuais. A interface de RA é materializada por um iPhone montado num suporte de cabeça do utilizador, assim como um conjunto de sensores sem fios para medição de parâmetros fisiológicos e de movimento. A posição e a velocidade do paciente são registadas por um tapete inteligente que inclui sensores capacitivos conectados a uma unidade de computação, caracterizada por comunicação via Wi-Fi. O cenário de treino em RA e os resultados experimentais correspondentes fazem parte desta dissertação

Feasibility of a walking virtual reality system for rehabilitation: objective and subjective parameters

[EN] Background: Even though virtual reality (VR) is increasingly used in rehabilitation, the implementation of walking navigation in VR still poses a technological challenge for current motion tracking systems. Different metaphors simulate locomotion without involving real gait kinematics, which can affect presence, orientation, spatial memory and cognition, and even performance. All these factors can dissuade their use in rehabilitation. We hypothesize that a marker-based head tracking solution would allow walking in VR with high sense of presence and without causing sickness. The objectives of this study were to determine the accuracy, the jitter, and the lag of the tracking system and its elicited sickness and presence in comparison of a CAVE system. Methods: The accuracy and the jitter around the working area at three different heights and the lag of the head tracking system were analyzed. In addition, 47 healthy subjects completed a search task that involved navigation in the walking VR system and in the CAVE system. Navigation was enabled by natural locomotion in the walking VR system and through a specific device in the CAVE system. An HMD was used as display in the walking VR system. After interacting with each system, subjects rated their sickness in a seven-point scale and their presence in the Slater-Usoh-Steed Questionnaire and a modified version of the Presence Questionnaire. Results: Better performance was registered at higher heights, where accuracy was less than 0.6 cm and the jitter was about 6 mm. The lag of the system was 120 ms. Participants reported that both systems caused similar low levels of sickness (about 2.4 over 7). However, ratings showed that the walking VR system elicited higher sense of presence than the CAVE system in both the Slater-Usoh-Steed Questionnaire (17.6 +/- 0.3 vs 14.6 +/- 0.6 over 21, respectively) and the modified Presence Questionnaire (107.4 +/- 2.0 vs 93.5 +/- 3.2 over 147, respectively). Conclusions: The marker-based solution provided accurate, robust, and fast head tracking to allow navigation in the VR system by walking without causing relevant sickness and promoting higher sense of presence than CAVE systems, thus enabling natural walking in full-scale environments, which can enhance the ecological validity of VR-based rehabilitation applications.The authors wish to thank the staff of LabHuman for their support in this project, especially José Miguel Martínez and José Roda for their assistance. 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Virtual reality-based assessment and rehabilitation of functional mobility

The advent of virtual reality (VR) as a tool for real-world training dates back to the mid-twentieth century and the early years of driving and flight simulators. These simulation environments, while far below the quality of today’s visual displays, proved to be advantageous to the learner due to the safe training environments the simulations provided. More recently, these training environments have proven beneficial in the transfer of user-learned skills from the simulated environment to the real world [5, 31, 48, 51, 57]. Of course the VR technology of today has come a long way. Contemporary displays boast high-resolution, wide-angle fields of view and increased portability. This has led to the evolution of new VR research and training applications in many different arenas, several of which are covered in other chapters of this book. This is true of clinical assessment and rehabilitation as well, as the field has recognized the potential advantages of incorporating VR technologies into patient training for almost 20 years [7, 10, 18, 45, 78]

Virtual Reality as a Therapy Tool for Walking Activities in Pediatric Neurorehabilitation: Usability and User Experience Evaluation

Background: Many essential walking activities in daily life, such as crossing a street, are challenging to practice in conventional therapeutic settings. Virtual environments (VEs) delivered through a virtual reality (VR) head-mounted display (HMD) would allow training such activities in a safe and attractive environment. Furthermore, the game-like character and high degree of immersion in these applications might help maintain or increase children's motivation and active participation during the rehabilitation process. Objective: This study aimed to investigate the usability, user experience, and acceptability of an immersive VE experienced through a VR HMD to train everyday life walking activities in pediatric neurorehabilitation. Methods: In a cross-sectional study, 21 youths (median age 12.1 years; range 6.8-17.7 years) with a neuromotor impairment undergoing inpatient or outpatient neurorehabilitation tested a VE experienced through the VR HMD Oculus Quest. The participants, accompanied by their physiotherapists, moved freely around a 4.4 by 10-meter VE, displaying a magical forest and featuring various gamified everyday activities in different game designs. Using their hands, represented in the VE, the participants could interact with the virtual objects placed throughout the VE and trigger visual and auditory feedback. Symptoms of cybersickness were checked, and usability, user experience, and acceptability were evaluated using customized questionnaires with a visual analog scale for youths and a 5-point Likert scale for their therapists. Results: None of the participants reported any signs of cybersickness after 20 minutes of VR HMD exposure time. They rated comfort (median 10/10) and movement ability (median 10/10) with the VR HMD as high. The VE was perceived as being really there by the majority (median 8/10), and the participants had a strong feeling of spatial presence in the VE (median 9.5/10). They enjoyed exploring the virtual world (median 10/10) and liked this new therapy approach (median 10/10). Therapists' acceptance of the VR HMD was high (4/5). There were 5 patients that needed more support than usual, mainly for supervision, when moving around with the VR HMD. Otherwise, therapists felt that the VR HMD hardly affected their patients' movement behavior (median 4.75/5), whereas it seemed to increase their level of therapy engagement (median 4/5) compared to conventional physiotherapy sessions. Conclusions: This study demonstrates the usability of an immersive VE delivered through a VR HMD to engage youths in the training of everyday walking activities. The participants' and therapists' positive ratings on user experience and acceptance further support the promising application of this technology as a future therapeutic tool in pediatric neurorehabilitation. Keywords: adolescent; auditory; child; feasibility study; feedback; head-mounted display; pediatric; rehabilitation; therapy; tool; usability; user; virtual reality; visual; walking; youth

Effects of sensory cueing in virtual motor rehabilitation. A review.

Objectives To critically identify studies that evaluate the effects of cueing in virtual motor rehabilitation in patients having different neurological disorders and to make recommendations for future studies. Methods Data from MEDLINE®, IEEExplore, Science Direct, Cochrane library and Web of Science was searched until February 2015. We included studies that investigate the effects of cueing in virtual motor rehabilitation related to interventions for upper or lower extremities using auditory, visual, and tactile cues on motor performance in non-immersive, semi-immersive, or fully immersive virtual environments. These studies compared virtual cueing with an alternative or no intervention. Results Ten studies with a total number of 153 patients were included in the review. All of them refer to the impact of cueing in virtual motor rehabilitation, regardless of the pathological condition. After selecting the articles, the following variables were extracted: year of publication, sample size, study design, type of cueing, intervention procedures, outcome measures, and main findings. The outcome evaluation was done at baseline and end of the treatment in most of the studies. All of studies except one showed improvements in some or all outcomes after intervention, or, in some cases, in favor of the virtual rehabilitation group compared to the control group. Conclusions Virtual cueing seems to be a promising approach to improve motor learning, providing a channel for non-pharmacological therapeutic intervention in different neurological disorders. However, further studies using larger and more homogeneous groups of patients are required to confirm these findings

Interactive Augmented Reality As A Support Tool For Parkinson’s Disease Rehabilitation Programs

In this thesis, an augmented reality system is proposed as an alternative to create multiple interactive virtual environments that might later be used in Parkinson’s Disease rehabilitation programs. The main objective of this thesis is to develop a Wearable Tangible Augmented Reality Environment focused on providing the sense of presence required to effectively immerse patients so that they are able to perform different tasks in context–specific scenarios. By using our system, patients are able to freely navigate different virtual environments. Moreover, by segmenting and then overlaying users’ hands and objects of interest above the 3D environment, patients have the ability to naturally interact with both real–life items as well as with virtually augmented objects using nothing but their bare hands. As part of this thesis, Parkinson’s Disease patients participated in a three–week dual– task assessment program in which several tasks were performed following a strict protocol. In order to assess patients’ performance, the tasks were carried out both in the real world and using the system. The findings of this thesis will help evaluate the viability of using augmented reality as an auxiliary tool for Parkinson’s Disease rehabilitation programs