An Empirical Evaluation On Vibrotactile Feedback For Wristband System

With the rapid development of mobile computing, wearable wrist-worn is becoming more and more popular. But the current vibrotactile feedback patterns of most wrist-worn devices are too simple to enable effective interaction in nonvisual scenarios. In this paper, we propose the wristband system with four vibrating motors placed in different positions in the wristband, providing multiple vibration patterns to transmit multi-semantic information for users in eyes-free scenarios. However, we just applied five vibrotactile patterns in experiments (positional up and down, horizontal diagonal, clockwise circular, and total vibration) after contrastive analyzing nine patterns in a pilot experiment. The two experiments with the same 12 participants perform the same experimental process in lab and outdoors. According to the experimental results, users can effectively distinguish the five patterns both in lab and outside, with approximately 90% accuracy (except clockwise circular vibration of outside experiment), proving these five vibration patterns can be used to output multi-semantic information. The system can be applied to eyes-free interaction scenarios for wrist-worn devices.Comment: 10 pages

Investigating the Usability of a Vibrotactile Torso Display for Improving Simulated Teleoperation Obstacle Avoidance

While unmanned ground vehicle (UGV) teleoperation is advantageous in terms of adaptability and safety, it introduces challenges resulting from the operator\u27s poor perception of the remote environment. Previous literature on the ability of haptic feedback to augment visual displays indicates that UGV obstacle avoidance information may be more meaningfully communicated via vibrotactile torso systems. Presenting this information so that operators can accurately detect the proximity from walls and obstructions could result in a significant reduction in errors, ultimately improving task performance and increasing the usability of teleoperation. The goal of the current study was to determine the degree to which a vibrotactile torso belt could improve UGV teleoperation performance over video feed alone in a simulated environment. Sixty operators controlled a UGV using a simulated video feed, while half also utilized a vibrotactile belt. Results indicated that the vibrotactile display did not improve navigational performance or decrease subjective workload over video feed alone. Possible reasons for this and limitations are discussed

HaptiSole: Wearable Haptic System in Vibrotactile Guidance Shoes for Visually Impaired Wayfinding

During the last decade, several Electronic Orientation Aids devices have been proposed to solve the autonomy problems of visually impaired people. When hearing is considered the primary sense for Visually Impaired people (VI) and it is generally loaded with the environment, the use of tactile sense can be considered a solution to transmit directional information. This paper presents a new wearable haptic system based on four motors implemented in shoes, while six directions can be played. This study aims to introduce an interface design and investigate an appropriate means of spatial information delivery through haptic sense. The first experiment of the proposed system was performed with 15 users in an indoor environment. The results showed that the users were able to recognize, with high accuracy, the directions displayed on their feet. The second experiment was conducted in an outdoor environment with five blindfolded users who were guided along 120 meters. The users, guided only by the haptic system, successfully reached their destinations. The potential of tactile-foot stimulation to help VI understand Electronic Orientation Aids (EOA) instructions was discussed, and future challenges were defined

Vibrotactile pattern recognition on the torso with one and two dimensional displays

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (leaves 27-28).This research focused on the evaluation of a tactile display that is used for navigation and communication. In the first experiment, a four by four array of vibrating motors (tactors) was mounted on the torso while the subject wore an Interceptor Body Armor (IBA) vest. Subjects were required to identify which of eight patterns was presented. The results indicated that subjects could recognize the patterns presented with perfect accuracy, which indicates that wearing heavy body armor over the display does not affect the ability to perceive tactile inputs. A second set of experiments involved a one-dimension tactile array of eight tactors worn around the waist. The results indicated that the subjects could recognize the six circumferential patterns presented with an accuracy of 98-100% correct. A further experiment confirmed that the linear tactile display could be used to provide cues about the location of an event in the environment. These experiments showed that identification of the vibrotactile patterns was slightly superior on the two-dimension tactile array on the torso as compared to the one-dimension tactile array around the waist.(cont.) When subjects were required to identify the location of an individual vibrating motor using the one-dimensional array they achieved an accuracy of 94-100% correct. This suggests that a linear tactile array can be used to present navigational cues.by Amy R. Lam.S.B

Haptic wearables as sensory replacement, sensory augmentation and trainer - a review

Sensory impairments decrease quality of life and can slow or hinder rehabilitation. Small, computationally powerful electronics have enabled the recent development of wearable systems aimed to improve function for individuals with sensory impairments. The purpose of this review is to synthesize current haptic wearable research for clinical applications involving sensory impairments. We define haptic wearables as untethered, ungrounded body worn devices that interact with skin directly or through clothing and can be used in natural environments outside a laboratory. Results of this review are categorized by degree of sensory impairment. Total impairment, such as in an amputee, blind, or deaf individual, involves haptics acting as sensory replacement; partial impairment, as is common in rehabilitation, involves haptics as sensory augmentation; and no impairment involves haptics as trainer. This review found that wearable haptic devices improved function for a variety of clinical applications including: rehabilitation, prosthetics, vestibular loss, osteoarthritis, vision loss and hearing loss. Future haptic wearables development should focus on clinical needs, intuitive and multimodal haptic displays, low energy demands, and biomechanical compliance for long-term usage

Mobile navigation: a multimodal approach

The functionality and processing power of mobile devices has increased dramatically over the last few years. Location based services and rich interactions are feasible with the majority of smart phones available today. However, whilst the capabilities of current devices afford rich interaction tailored to the user in mobile situations, they are still linked with desktop style interactions. Spatially situated virtual objects are used to represent multiple forms of information. Ranging from nav- igation beacons to places of interest and gaming objects. This thesis gives an review of the current literature of the use of virtual objects and examines the role of vibrotactile feedback for egocentric heading detection for virtual objects. Experiment results are also reported showing users can utilise vibrotactile feedback for heading acquisition. Possible future steps include combining directions and distance information for mobile navigation systems

Perception of Time-Discrete Haptic Feedback on the Waist is Invariant with Gait Events

The effectiveness of haptic feedback devices highly depends on the perception of tactile stimuli, which differs across body parts and can be affected by movement. In this study, a novel wearable sensory feedback apparatus made of a pair of pressure-sensitive insoles and a belt equipped with vibrotactile units is presented; the device provides time-discrete vibrations around the waist, synchronized with biomechanically-relevant gait events during walking. Experiments with fifteen healthy volunteers were carried out to investigate users' tactile perception on the waist. Stimuli of different intensities were provided at twelve locations, each time synchronously with one pre-defined gait event (i.e. heel strike, flat foot or toe off), following a pseudo-random stimulation sequence. Reaction time, detection rate and localization accuracy were analyzed as functions of the stimulation level and site and the effect of gait events on perception was investigated. Results revealed that above-threshold stimuli (i.e. vibrations characterized by acceleration amplitudes of 1.92g and 2.13g and frequencies of 100 Hz and 150 Hz, respectively) can be effectively perceived in all the sites and successfully localized when the intertactor spacing is set to 10 cm. Moreover, it was found that perception of time-discrete vibrations was not affected by phase-related gating mechanisms, suggesting that the waist could be considered as a preferred body region for delivering haptic feedback during walking

Haptic Guidance in Dynamic Environments Using Optimal Reciprocal Collision Avoidance

Human guidance in situations where the users cannot rely on their main sensory modalities, such as assistive or search-and-rescue scenarios, is a challenging task. In this letter, we address the problem of guiding users along collision-free paths in dynamic environments, assuming that they cannot rely on their main sensory modalities. In order to safely guide the subjects, we adapt the optimal reciprocal collision avoidance to our specific problem. The proposed algorithm takes into account the stimuli which can be displayed to the users and the motion uncertainty of the users when reacting to the provided stimuli. The proposed algorithm was evaluated in three different dynamic scenarios. A total of 18 blindfolded human subjects were asked to follow haptic cues in order to reach a target area while avoiding real static obstacles and moving users. Three metrics such as time to reach the goal, length of the trajectories, and minimal distance from the obstacles are considered to compare results obtained using this approach and experiments performed without visual impairments. Experimental results reveal that blindfolded subjects are successfully able to avoid collisions and safely reach the targets in all the performed trials. Although in this letter we display directional cues via haptic stimuli, we believe that the proposed approach can be general and tuned to work with different haptic interfaces and/or feedback modalities

Relative vibrotactile spatial acuity of the torso

While tactile acuity for pressure has been extensively investigated, far less is known about acuity for vibrotactile stimulation. Vibrotactile acuity is important however, as such stimulation is used in many applications, including sensory substitution devices. We tested discrimination of vibrotactile stimulation from eccentric rotating mass motors with in-plane vibration. In 3 experiments, we tested gradually decreasing center-to-center (c/c) distances from 30 mm (experiment 1) to 13 mm (experiment 3). Observers judged whether a second vibrating stimulator (‘tactor’) was to the left or right or in the same place as a first one that came on 250 ms before the onset of the second (with a 50-ms inter-stimulus interval). The results show that while accuracy tends to decrease the closer the tactors are, discrimination accuracy is still well above chance for the smallest distance, which places the threshold for vibrotactile stimulation well below 13 mm, which is lower than recent estimates. The results cast new light on vibrotactile sensitivity and can furthermore be of use in the design of devices that convey information through vibrotactile stimulation.Peer Reviewe