Upper Limb Motion Profile During Small to Medium Time-Limited Reaching Tasks in a VR Based Robotic Training Environment

2007 ◽  
Author(s):  
Evagoras G. Xydas ◽  
Loucas S. Louca
Keyword(s):  
Virtual Environments ◽  
Virtual Environment ◽  
Upper Limb ◽  
Haptic Feedback ◽  
Control Function ◽  
Rehabilitation Robotics ◽  
Working Environment ◽  
Therapeutic Effects ◽  
Robotic Training ◽  
Minimum Jerk

In the area of rehabilitation robotics, many researchers have investigated the therapeutic effects of forces that are proportional to the difference of the user’s hand trajectory with an optimum trajectory that is usually based on the Minimum Jerk Model (MJM). Forces applied in different studies were based on MJM trajectory variables, e.g., velocity, acceleration, position, etc. Consequently, MJM is a key component for upper limb robotic rehabilitation. However, it is critical to establish the validity of this model in the working environment prior of employing it as a reference control function. This work investigates the validity of the MJM under a haptic-virtual environment. The original ‘real’ tests (with no obstacles) that were employed for validating the MJM in planar motion are duplicated in a virtual environment. Haptic feedback is achieved with the use of a Phantom 1.5 High Force haptic interface. Experiments with healthy users are performed to investigate the validity of the MJM in virtual reality conditions. The experiments demonstrated that the MJM is also valid in virtual environments. Nevertheless it was found that in the virtual world, higher time durations are required for completing the tasks than in the real world. The results of this work will be used in the design of haptic-virtual environments for the rehabilitation of upper limbs of people with neuro-disabilities. Therapeutic forces based on the MJM can be applied given that the Minimum Jerk Model is valid in virtual environments.

Upper Limb Assessment of People With Multiple Sclerosis With the Use of a Haptic Nine-Hole Peg-Board Test

2008 ◽  
Author(s):  
Evagoras G. Xydas ◽  
Loucas S. Louca
Keyword(s):  
Multiple Sclerosis ◽  
Young Adults ◽  
Virtual Environment ◽  
Motion Analysis ◽  
Upper Limb ◽  
Three Dimensional ◽  
Haptic Interface ◽  
Robotic Arm ◽  
Minimum Jerk ◽  
Board Test

In this work, a nine-hole peg-board test (NHPT) arrangement is implemented in a Virtual Environment with the use of a Haptic Interface that has the form of a small robotic arm. The Haptic NHPT is used as a mean for investigating the validity of a quantitative metric, which is based on smoothness maximization, as a possible assessment parameter for three dimensional reaching tasks. More specifically this study refers to the assessment of people with multiple sclerosis. The basic metric is developed by combining a neurophysical concept, which suggests that the three dimensional trajectories are piecewise planar, with the minimum jerk model (MJM) which in turn maximizes the smoothness along a predefined path. A total number of sixteen persons participated in the study. From these, nine were healthy young adults and seven were people with MS of various ages and at different stages of disease progress. All participants performed the exercise three times, of which only the second and third were used in the analyses. The results showed that the employed procedure was successful for developing a motion analysis metric for the smoothness in three dimensional trajectories. Also, a clear and traceable difference in performance appeared between the two groups, by using the developed assessment metric.

Simulating Haptic Feedback Using Vision: A Survey of Research and Applications of Pseudo-Haptic Feedback

2009 ◽  
Vol 18 (1) ◽  
pp. 39-53 ◽  
Author(s):  
Anatole Lécuyer
Keyword(s):  
Virtual Reality ◽  
Virtual Environments ◽  
Virtual Environment ◽  
Visual Feedback ◽  
Vocational Training ◽  
Haptic Perception ◽  
Haptic Feedback ◽  
Virtual Object ◽  
Milling Machine ◽  
Medical Simulator

This paper presents a survey of the main results obtained in the field of “pseudo-haptic feedback”: a technique meant to simulate haptic sensations in virtual environments using visual feedback and properties of human visuo-haptic perception. Pseudo-haptic feedback uses vision to distort haptic perception and verges on haptic illusions. Pseudo-haptic feedback has been used to simulate various haptic properties such as the stiffness of a virtual spring, the texture of an image, or the mass of a virtual object. This paper describes the several experiments in which these haptic properties were simulated. It assesses the definition and the properties of pseudo-haptic feedback. It also describes several virtual reality applications in which pseudo-haptic feedback has been successfully implemented, such as a virtual environment for vocational training of milling machine operations, or a medical simulator for training in regional anesthesia procedures.

Perception-Based Traffic Control for Shared Haptic Virtual Environments

2014 ◽  
Vol 23 (3) ◽  
pp. 320-338 ◽  
Author(s):  
Clemens Schuwerk ◽  
Giulia Paggetti ◽  
Rahul Chaudhari ◽  
Eckehard Steinbach
Keyword(s):  
Virtual Environments ◽  
Virtual Environment ◽  
Traffic Control ◽  
Force Feedback ◽  
Haptic Feedback ◽  
Dead Reckoning ◽  
Distributed Applications ◽  
Haptic Device ◽  
Object State ◽  
Feedback Quality

Shared Haptic Virtual Environments (SHVEs) are often realized using a client–server communication architecture. In this case, a centralized physics engine, running on the server, is used to simulate the object-states in the virtual environment (VE). At the clients, a copy of the VE is maintained and used to render the interaction forces locally, which are then displayed to the human through a haptic device. While this architecture ensures stability in the coupling between the haptic device and the virtual environment, it necessitates a high number of object-state update packets transmitted from the server to the clients to achieve satisfactory force feedback quality. In this paper, we propose a perception-based traffic control scheme to reduce the number of object-state update packets by allowing a variable but not perceivable object-state error at the client. To find a balance between packet rate reduction and force rendering fidelity, our approach uses different error thresholds for the visual and haptic modality, where the haptic thresholds are determined by psychophysical experiments in this paper. Force feedback quality is evaluated with subjective tests for a variety of different traffic control parameter settings. The results show that the proposed scheme reduces the packet rate by up to 97%, compared to communication approaches that work without data reduction. At the same time, the proposed scheme does not degrade the haptic feedback quality significantly. Finally, it outperforms well-known dead reckoning, commonly used in visual-only distributed applications.

scholarly journals Three-Axis Pneumatic Haptic Display for the Mechanical and Thermal Stimulation of a Human Finger Pad

Actuators ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 60
Author(s):  
Eun-Hyuk Lee ◽  
Sang-Hoon Kim ◽  
Kwang-Seok Yun
Keyword(s):  
Pulse Width Modulation ◽  
Haptic Feedback ◽  
Control Function ◽  
Lateral Displacement ◽  
Gain Control ◽  
Haptic Display ◽  
Positional Accuracy ◽  
Control Module ◽  
Haptic Displays ◽  
Human Finger

Haptic displays have been developed to provide operators with rich tactile information using simple structures. In this study, a three-axis tactile actuator capable of thermal display was developed to deliver tactile senses more realistically and intuitively. The proposed haptic display uses pneumatic pressure to provide shear and normal tactile pressure through an inflation of the balloons inherent in the device. The device provides a lateral displacement of ±1.5 mm for shear haptic feedback and a vertical inflation of the balloon of up to 3.7 mm for normal haptic feedback. It is designed to deliver thermal feedback to the operator through the attachment of a heater to the finger stage of the device, in addition to mechanical haptic feedback. A custom-designed control module is employed to generate appropriate haptic feedback by computing signals from sensors or control computers. This control module has a manual gain control function to compensate for the force exerted on the device by the user’s fingers. Experimental results showed that it could improve the positional accuracy and linearity of the device and minimize hysteresis phenomena. The temperature of the device could be controlled by a pulse-width modulation signal from room temperature to 90 °C. Psychophysical experiments show that cognitive accuracy is affected by gain, and temperature is not significantly affected.

scholarly journals Perceptual uncertainty and action consequences independently affect hand movements in a virtual environment

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Martin Giesel ◽  
Anna Nowakowska ◽  
Julie M. Harris ◽  
Constanze Hesse
Keyword(s):  
Virtual Environments ◽  
Virtual Environment ◽  
Motor Skills ◽  
Hand Movements ◽  
Perceptual Information ◽  
Avoidance Task ◽  
Natural Environments ◽  
Motor Behaviour ◽  
Virtual And Augmented Reality

AbstractWhen we use virtual and augmented reality (VR/AR) environments to investigate behaviour or train motor skills, we expect that the insights or skills acquired in VR/AR transfer to real-world settings. Motor behaviour is strongly influenced by perceptual uncertainty and the expected consequences of actions. VR/AR differ in both of these aspects from natural environments. Perceptual information in VR/AR is less reliable than in natural environments, and the knowledge of acting in a virtual environment might modulate our expectations of action consequences. Using mirror reflections to create a virtual environment free of perceptual artefacts, we show that hand movements in an obstacle avoidance task systematically differed between real and virtual obstacles and that these behavioural differences occurred independent of the quality of the available perceptual information. This suggests that even when perceptual correspondence between natural and virtual environments is achieved, action correspondence does not necessarily follow due to the disparity in the expected consequences of actions in the two environments.

Dropouts and Aftereffects: Examining General Accessibility to Virtual Environment Technology

2002 ◽  
Vol 46 (26) ◽  
pp. 2114-2118 ◽  
Author(s):  
Kay M. Stanney ◽  
Kelly S. Kingdon ◽  
Robert S. Kennedy
Keyword(s):  
Virtual Environments ◽  
Virtual Environment ◽  
Broad Spectrum ◽  
General Public ◽  
Dropout Rates ◽  
Environment Exposure ◽  
Oculomotor Disturbances ◽  
A Minor

Are current virtual environments (VEs) usable by the broad spectrum of people who may wish to utilize this technology? The current study, which examined over 1000 participants, indicates the answer to this question is a definitive ‘no’. Virtual environment exposure was found to cause people to vomit (1.1%), experience nausea (71%), disorientation (70%), and oculomotor disturbances (79%). Overall, 88% of participants reported some level of adverse symptomatology, ranging from a minor headache to vomiting and intense vertigo. These disturbances led 12% of those exposed to prematurely cease their interaction. Dropout rates as high as nearly 50% were found in exposures of 1 hr in length. In addition, long-term aftereffects were found, including headaches, drowsiness, nausea, and fatigue. These problems could substantially reduce the accessibility of VE technology by the general public and thus must be resolved if this technology is to be widely adopted.

The VEOS Project

1994 ◽  
Vol 3 (2) ◽  
pp. 111-129 ◽  
Author(s):  
William Bricken ◽  
Geoffrey Coco
Keyword(s):  
Rapid Prototyping ◽  
Virtual Environments ◽  
Virtual Environment ◽  
Object Oriented ◽  
Organization Structure ◽  
Object Oriented Programming ◽  
Iterative Refinement ◽  
Software Infrastructure ◽  
Human Interface ◽  
Heterogeneous Distributed Computing

The Virtual Environment Operating Shell (veos) was developed at University of Washington's Human Interface Technology Laboratory as software infrastructure for the lab's research in virtual environments. veos was designed from scratch to provide a comprehensive and unified management facility to support generation of, interaction with, and maintenance of virtual environments. VEOS emphasizes rapid prototyping, heterogeneous distributed computing, and portability. We discuss the design, philosophy and implementation of veos in depth. Within the Kernel, the shared database transformations are pattern-directed, communications are asynchronous, and the programmer's interface is LISP. An entity-based metaphor extends object-oriented programming to systems-oriented programming. Entities provide first-class environments and biological programming constructs such as perceive, react, and persist. The organization, structure, and programming of entities are discussed in detail. The article concludes with a description of the applications that have contributed to the iterative refinement of the VEOS software.

scholarly journals Crowd behaviour during high-stress evacuations in an immersive virtual environment

2016 ◽  
Vol 13 (122) ◽  
pp. 20160414 ◽  
Author(s):  
Mehdi Moussaïd ◽  
Mubbasir Kapadia ◽  
Tyler Thrash ◽  
Robert W. Sumner ◽  
Markus Gross ◽  
...  
Keyword(s):  
Virtual Environments ◽  
Virtual Environment ◽  
Human Subjects ◽  
High Stress ◽  
Three Dimensional ◽  
Real Life ◽  
Social Conventions ◽  
Emergency Situations ◽  
Crowd Behaviour ◽  
The Individual

Understanding the collective dynamics of crowd movements during stressful emergency situations is central to reducing the risk of deadly crowd disasters. Yet, their systematic experimental study remains a challenging open problem due to ethical and methodological constraints. In this paper, we demonstrate the viability of shared three-dimensional virtual environments as an experimental platform for conducting crowd experiments with real people. In particular, we show that crowds of real human subjects moving and interacting in an immersive three-dimensional virtual environment exhibit typical patterns of real crowds as observed in real-life crowded situations. These include the manifestation of social conventions and the emergence of self-organized patterns during egress scenarios. High-stress evacuation experiments conducted in this virtual environment reveal movements characterized by mass herding and dangerous overcrowding as they occur in crowd disasters. We describe the behavioural mechanisms at play under such extreme conditions and identify critical zones where overcrowding may occur. Furthermore, we show that herding spontaneously emerges from a density effect without the need to assume an increase of the individual tendency to imitate peers. Our experiments reveal the promise of immersive virtual environments as an ethical, cost-efficient, yet accurate platform for exploring crowd behaviour in high-risk situations with real human subjects.

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