Collision Awareness Using Vibrotactile Arrays

What is often missing from many virtual worlds is a physical sense of the confinement and constraint of the virtual environment. To address this issue, we present a method for providing localized cutaneous vibratory feedback to the user’s right arm. We created a sleeve of tactors linked to a real-time human model that activates when the corresponding body area collides with an object. The hypothesis is that vibrotactile feedback to body areas provides the wearer sufficient guidance to acertain the existence and physical realism of access paths and body configurations. The results of human subject experiments clearly show that the use of full arm vibrotactile feedback improves performance over purely visual feedback in navigating the virtual environment. These results validate the empirical performance of this concept

Multimodal “sensory illusions” for improving spatial awareness in virtual environments

Inaccurate judgement of distances in virtual environments (VEs) restricts their usefulness for engineering development, in which engineers must have a good understanding of the spaces they are designing. Multimodal feedback can improve depth perception in VEs, but this has yet to be implemented and tested in engineering applications with systems which provide haptic feedback to the body. The project reported in this paper will develop a multimodal VE to improve engineers’ understanding of 3D spaces. It will test the concept of “sensory illusions” where the point of collision in the VE differs to the point of haptic feedback on the body. This will permit the use of fewer vibrotactile devices and therefore the development of a more wearable system. This paper describes related work in multisensory and tactile stimulation which suggests that our perception of a stimulus is not fixed to the point of contact

Being a Part of the Crowd: Towards Validating VR Crowds Using Presence

Crowd simulation models are currently lacking a commonly accepted validation method. In this paper, we propose level of presence achieved by a human in a virtual environment (VE) as a metric for virtual crowd behavior. Using experimental evidence from the presence literature and the results of a pilot experiment that we ran, we explore the egocentric features that a crowd simulation model should have in order to achieve high levels of presence and thus be used as a framework for validation of simulated crowd behavior. We implemented four crowd models for our pilot experiment: social forces, rule based, cellular automata and HiDAC. Participants interacted with the crowd members of each model in an immersive virtual environment for the purpose of studying presence in virtual crowds, with the goal of establishing the basis for a future validation method

Multimodal "Sensory Illusions" for Improving Spatial Awareness in Virtual Environments

Inaccurate judgement of distances in virtual environments (VEs) restricts their usefulness for engineering development, in which engineers must have a good understanding of the spaces they are designing. Multimodal feedback can improve depth perception in VEs, but this has yet to be implemented and tested in engineering applications with systems which provide haptic feedback to the body. The project reported in this paper will develop a multimodal VE to improve engineers’ understanding of 3D spaces. It will test the concept of “sensory illusions” where the point of collision in the VE differs to the point of haptic feedback on the body. This will permit the use of fewer vibrotactile devices and therefore the development of a more wearable system. This paper describes related work in multisensory and tactile stimulation which suggests that our perception of a stimulus is not fixed to the point of contact

Augmenting Visual Feedback Using Sensory Substitution

Direct interaction in virtual environments can be realized using relatively simple hardware, such as standard webcams and monitors. The result is a large gap between the stimuli existing in real-world interactions and those provided in the virtual environment. This leads to reduced efficiency and effectiveness when performing tasks. Conceivably these missing stimuli might be supplied through a visual modality, using sensory substitution. This work suggests a display technique that attempts to usefully and non-detrimentally employ sensory substitution to display proximity, tactile, and force information. We solve three problems with existing feedback mechanisms. Attempting to add information to existing visuals, we need to balance: not occluding the existing visual output; not causing the user to look away from the existing visual output, or otherwise distracting the user; and displaying as much new information as possible. We assume the user interacts with a virtual environment consisting of a manually controlled probe and a set of surfaces. Our solution is a pseudo-shadow: a shadow-like projection of the user's probe onto the surface being explored or manipulated. Instead of drawing the probe, we only draw the pseudo-shadow, and use it as a canvas on which to add other information. Static information is displayed by varying the parameters of a procedural texture rendered in the pseudo-shadow. The probe velocity and probe-surface distance modify this texture to convey dynamic information. Much of the computation occurs on the GPU, so the pseudo-shadow renders quickly enough for real-time interaction. As a result, this work contains three contributions: a simple collision detection and handling mechanism that can generalize to distance-based force fields; a way to display content during probe-surface interaction that reduces occlusion and spatial distraction; and a way to visually convey small-scale tactile texture

Effectiveness of Vibration-based Haptic Feedback Effects for 3D Object Manipulation

This research explores the development of vibration-based haptic feedback for a mouse-like computer input device. The haptic feedback is intended to be used in 3D virtual environments to provide users of the environment with information that is difficult to convey visually, such as collisions between objects. Previous research into vibrotactile haptic feedback can generally be split into two broad categories: single tactor handheld devices; and multiple tactor devices that are attached to the body. This research details the development of a vibrotactile feedback device that merges the two categories, creating a handheld device with multiple tactors. Building on previous research, a prototype device was developed. The device consisted of a semi-sphere with a radius of 34 mm, mounted on a PVC disk with a radius of 34 mm and a height of 18 mm. Four tactors were placed equidistantly about the equator of the PVC disk. Unfortunately, vibrations from a single tactor caused the entire device to shake due to the rigid plastic housing for the tactors. This made it difficult to accurately detect which tactor was vibrating. A second prototype was therefore developed with tactors attached to elastic bands. When a tactor vibrates, the elastic bands dampen the vibration, reducing the vibration in the rest of the device. The goal of the second prototype was to increase the accuracy in localizing the vibrating tactor. An experiment was performed to compare the two devices. The study participants grasped one of the device prototypes as they would hold a computer mouse. During each trial, a random tactor would vibrate. By pushing a key on the keyboard, the participants indicated when they detected vibration. They then pushed another key to indicate which tactor had been vibrating. The procedure was then repeated for the other device. Detection of the vibration was faster (p < 0.01) and more accurate (p < 0.001) with the soft shell design than with the hard shell design. In a post-experiment questionnaire, participants preferred the soft shell design to the hard shell design. Based on the results of the experiment, a mould was created for building future prototypes. The mould allows for the rapid creation of devices from silicone. Silicone was chosen as a material because it can easily be moulded and is available in different levels of hardness. The hardness of the silicone can be used to control the amount of damping of the vibrations. To increase the vibration damping, a softer silicone can be used. Several recommendations for future prototypes and experiments are made