Mechanical and psychophysical studies of surface wave propagation during vibrotactile stimulation

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 50-51).Vibrotactile displays are based on mechanical stimulation delivered using an array of motors to communicate with the user. The way in which the display's motors are spaced and positioned on the body can have a significant impact on the effectiveness of communication, especially for tactile displays used to convey spatial information. The objective of the present research was to determine how the surface waves induced by vibrotactile stimulation of the skin varied as a function of the site on the body where the motors were mounted, and how these waves influenced the ability to localize vibrotactile stimulation. Three locations on the body were selected for study: the palm, the forearm, and the thigh. A flexible printed circuit board containing 3-axis micro-accelerometers was fabricated to measure the amplitude and frequency of surface waves produced by a vibrating motor at each body site. Results of these experiments showed significant differences in the frequency and amplitude of vibration on the glabrous skin on the palm as compared to the hairy skin on the arm and thigh. The palm had the highest frequency and lowest amplitude surface waves, and the forearm and thigh were very similar with lower frequency higher amplitude surface waves. No anisotropies were found from surface wave measurements. Most wave attenuation occurred within the first 8 mm from the motor, but there were still detectable amplitudes at a distance of 24 mm from the motor, which suggests that motor spacing should be at least 24 mm for this type of motor when used for precise spatial localization. A series of psychophysical experiments was conducted using a three-by-three array of motors in which the ability of subjects to localize the point of stimulation in an array was determined at each of the three body locations. The results from these experiments indicated that the palm had the highest localization accuracy (81% correct) as compared to the forearm and thigh which had similar localization accuracies (49% correct on forearm, 45% correct on thigh). Accuracy on the palm and forearm improved when the motor spacing increased from 8 mm to 16 mm, but increased spacing did not improve accuracy on the thigh. The results also showed that subjects were more able to identify the column of activation as opposed to the row of activation, which suggests a higher spatial acuity along the mediallateral as opposed to proximal-distal axis. The localization experiments indicate that glabrous skin is better suited for precise spatial localization than hairy skin, and that precise spatial localization requires an inter-motor spacing of more than 16 mm at these sites.by Katherine O. Sofia.S.M

Vibrotactile feedback as a countermeasure for spatial disorientation

Spaceflight can make astronauts susceptible to spatial disorientation which is one of the leading causes of fatal aircraft accidents. In our experiment, blindfolded participants used a joystick to balance themselves while inside a multi-axis rotation device (MARS) in either the vertical or horizontal roll plane. On Day 1, in the vertical roll plane (Earth analog condition) participants could use gravitational cues and therefore had a good sense of their orientation. On Day 2, in the horizontal roll plane (spaceflight analog condition) participants could not use gravitational cues and rapidly became disoriented and showed minimal learning and poor performance. One potential countermeasure for spatial disorientation is vibrotactile feedback that conveys body orientation provided by small vibrating devices applied to the skin. Orientation-dependent vibrotactile feedback provided to one group enhanced performance in the spaceflight condition but the participants reported a conflict between the accurate vibrotactile cues and their erroneous perception of their orientation. Specialized vibrotactile training on Day 1 provided to another group resulted in significantly better learning and performance in the spaceflight analog task with vibrotactile cueing. In this training, participants in the Earth analog condition on Day 1 were required to disengage from the task of aligning with the gravitational vertical encoded by natural vestibular/somatosensory afference and had to align with randomized non-vertical directions of balance signaled by vibrotactile feedback. At the end of Day 2, we deactivated the vibrotactile feedback after both vibration-cued groups had practiced with it in the spaceflight analog condition. They performed as well as the group who did not have any vibrotactile feedback. We conclude that after appropriate training, vibrotactile orientation feedback augments dynamic spatial orientation and does not lead to any negative dependence

Navigation Method Enhancing Music Listening Experience by Stimulating Both Neck Sides with Modulated Music Vibration

We propose a method that stimulates music vibration (generated from and synchronized with musical signals), modulated by the direction and distance to the target, on both sides of a user's neck with Hapbeat, a necklace-type haptic device. We conducted three experiments to confirm that the proposed method can achieve both haptic navigation and enhance the music listening experience. Experiment 1 consisted of conducting a questionnaire survey to examine the effect of stimulating music vibrations. Experiment 2 evaluated the accuracy (deg) of users' ability to adjust their direction toward a target using the proposed method. Experiment 3 examined the ability of four different navigation methods by performing navigation tasks in a virtual environment. The results of the experiments showed that stimulating music vibration enhanced the music listening experience, and that the proposed method is able to provide sufficient information to guide the users: accuracy in identifying directions was about 20\textdegree, participants reached the target in all navigation tasks, and in about 80\% of all trials participants reached the target using the shortest route. Furthermore, the proposed method succeeded in conveying distance information, and Hapbeat can be combined with conventional navigation methods without interfering with music listening.Comment: 12 pages, 8 figure

Haptic Navigation Cues on the Steering Wheel

Haptic feedback is used in cars to reduce visual inattention. While tactile feedback like vibration can be influenced by the car's movement, thermal and cutaneous push feedback should be independent of such interference. This paper presents two driving simulator studies investigating novel tactile feedback on the steering wheel for navigation. First, devices on one side of the steering wheel were warmed, indicating the turning direction, while those on the other side were cooled. This thermal feedback was compared to audio. The thermal navigation lead to 94.2% correct recognitions of warnings 200m before the turn and to 91.7% correct turns. Speech had perfect recognition for both. In the second experiment, only the destination side was indicated thermally, and this design was compared to cutaneous push feedback. The simplified thermal feedback design did not increase recognition, but cutaneous push feedback had high recognition rates (100% for 200 m warnings, 98% for turns)

Customizable Wearable Vibrotactile Display for Gait Biofeedback Research

ME450 Capstone Design and Manufacturing Experience: Winter 2021Approximately a third of American adults experience balance problems throughout their lifetime which can lead to a fear of falling, activity avoidance, and an increasingly sedentary lifestyle. While gait and balance training regimens are the most common therapeutic solution for adults with increased risk for falling, interventions that involve personalized biofeedback have been successfully shown to improve standing balance in research studies; however, it is still unclear how best to provide meaningful biofeedback during gait-related activities. Current gait correction systems are limited to providing feedback on a single gait parameter which cannot capture the full complexity of gait, and commonly use only one feedback scheme/modality. Additionally, many devices cannot provide the device wearer with immediate feedback. Therefore, there is a need to develop a customizable/reconfigurable wearable device to be used in a research setting, which will explore the effects of vibrotactile feedback on individuals with vestibular disorders. This device must be able to gather information on multiple kinematic parameters related to gait and provide vibrotactile feedback for the device wearer to interpret and correct their balance irregularities within each testing trial. Ultimately, this research platform will inform the development of a clinic-based and home-based biofeedback system.Christopher DiCesare, Safa Jabri, Kathleen Sienko: Sienko Research Labhttp://deepblue.lib.umich.edu/bitstream/2027.42/167651/1/Team_7-Customizable_Wearable_Vibrotactile_Display_for_Gait_Biofeedback_Research.pd

A Haptic Feedback System for Lower Limb Amputees Based on Gait Event Detection

Lower limb amputation has significant effects on a person’s quality of life and ability to perform activities of daily living. Prescription of prosthetic device post amputation aims to help restore some degrees of mobility function, however studies have shown evidence of low balance confidence and higher risk of falling among amputee community, especially those suffering from above knee amputation. While advanced prostheses offer better control, they often lack a form of feedback that delivers the awareness of the limb position to the prosthetic user while walking. This research presents the development and evaluation of a wearable skinstretch haptic feedback system intended to deliver cues of two crucial gait events, namely the Initial Contact (IC) and Toe-off (TO) to its wearer. The system comprises a haptic module that applies lateral skin-stretch on the upper leg or the trunk, corresponding to the gait event detection module based on Inertial Measurement Unit (IMU) attached at the shank. The design and development iterations of the haptic module is presented, and characterization of the feedback parameters is discussed. The validation of the gait event detection module is carried out and finally the integration of the haptic feedback system is described. Experimental work with healthy subjects and an amputee indicated good perceptibility of the feedback during static and dynamic (walking) condition, although higher magnitude of stretch was required to perceive the feedback during dynamic condition. User response time during dynamic activity showed that the haptic feedback system is suitable for delivering cues of IC and TO within the duration of the stance phase. In addition, feedback delivered in discernible patterns can be learned and adapted by the subjects. Finally, a case study was carried out with an above-knee amputee to assess the effects of the haptic feedback on spatio-temporal gait parameters and on the vertical ground reaction force during treadmill and overground walking. The research presented in this report introduces a novel design of a haptic feedback device. As such, the outcome includes a well-controlled skin-stretch effect which contributes to the research by investigating skin-stretch feedback for conveying discrete event information rather than conveying direction information as presented in other studies. In addition, it is found that stretch magnitude as small as 3 mm could be perceived in short duration of 150 ms during dynamic condition, making it a suitable alternative to other widely investigated haptic modality such as vibration for ambulatory feedback application. With continuous training, the haptic feedback system could possibly benefit lower limb amputees by creating awareness of the limb placement during ambulation, potentially reducing visual dependency and increasing walking confidence

Designing Tactile Interfaces for Abstract Interpersonal Communication, Pedestrian Navigation and Motorcyclists Navigation

The tactile medium of communication with users is appropriate for displaying information in situations where auditory and visual mediums are saturated. There are situations where a subject's ability to receive information through either of these channels is severely restricted by the environment they are in or through any physical impairments that the subject may have. In this project, we have focused on two groups of users who need sustained visual and auditory focus in their task: Soldiers on the battle field and motorcyclists. Soldiers on the battle field use their visual and auditory capabilities to maintain awareness of their environment to guard themselves from enemy assault. One of the major challenges to coordination in a hazardous environment is maintaining communication between team members while mitigating cognitive load. Compromise in communication between team members may result in mistakes that can adversely affect the outcome of a mission. We have built two vibrotactile displays, Tactor I and Tactor II, each with nine actuators arranged in a three-by-three matrix with differing contact areas that can represent a total of 511 shapes. We used two dimensions of tactile medium, shapes and waveforms, to represent verb phrases and evaluated ability of users to perceive verb phrases the tactile code. We evaluated the effectiveness of communicating verb phrases while the users were performing two tasks simultaneously. The results showed that performing additional visual task did not affect the accuracy or the time taken to perceive tactile codes. Another challenge in coordinating Soldiers on a battle field is navigating them to respective assembly areas. We have developed HaptiGo, a lightweight haptic vest that provides pedestrians both navigational intelligence and obstacle detection capabilities. HaptiGo consists of optimally-placed vibro-tactile sensors that utilize natural and small form factor interaction cues, thus emulating the sensation of being passively guided towards the intended direction. We evaluated HaptiGo and found that it was able to successfully navigate users with timely alerts of incoming obstacles without increasing cognitive load, thereby increasing their environmental awareness. Additionally, we show that users are able to respond to directional information without training. The needs of motorcyclists are di erent from those of Soldiers. Motorcyclists' need to maintain visual and auditory situational awareness at all times is crucial since they are highly exposed on the road. Route guidance systems, such as the Garmin, have been well tested on automobilists, but remain much less safe for use by motorcyclists. Audio/visual routing systems decrease motorcyclists' situational awareness and vehicle control, and thus increase the chances of an accident. To enable motorcyclists to take advantage of route guidance while maintaining situational awareness, we created HaptiMoto, a wearable haptic route guidance system. HaptiMoto uses tactile signals to encode the distance and direction of approaching turns, thus avoiding interference with audio/visual awareness. Evaluations show that HaptiMoto is intuitive for motorcyclists, and a safer alternative to existing solutions

Haptics: Science, Technology, Applications

This open access book constitutes the proceedings of the 13th International Conference on Human Haptic Sensing and Touch Enabled Computer Applications, EuroHaptics 2022, held in Hamburg, Germany, in May 2022. The 36 regular papers included in this book were carefully reviewed and selected from 129 submissions. They were organized in topical sections as follows: haptic science; haptic technology; and haptic applications

Ubiquitäre Systeme (Seminar) und Mobile Computing (Proseminar) WS 2016/17. Mobile und Verteilte Systeme. Ubiquitous Computing. Teil XIV

Diese Arbeit wird einen Überblick über virtuelle intelligente Assistenten (VIA), die im deutschen auch oft als Sprachassistenten bezeichnet werden, geben. Es werden die verschiedenen Arten von VIA gezeigt und in welchem Zusammenhang sie momentan schon genutzt werden. Als Beispiel werden einige aktuelle Assistenten dienen. Zudem werden neben den Möglichkeiten der Programme, auch noch die Grenzen dieser Technik dargestellt und mögliche Verbesserungen und Optimierungen für die Zukunft besprochen. Ebenfalls wird das empfindliche Thema Datenschutz mit Bezug auf die VIA behandelt. Am Ende des zweiten Teils gehen wir auf die aktuelle Beliebtheit und Nutzung der Anwendungen ein. Im dritten Abschnitt wird dann die Funktionsweise der Software im Hintergrund der Assistenten betrachtet. Es wird der allgemeine Aufbau eines VIA skizziert. Zudem werden zwei Modelle für die Arbeitsweise der Sprachassistenten betrachtet. Dazu werden auch einige theoretische Konzepte wie Ontologien, Knowledge Graphen und POMDP (partially observable Markov decision process) beleuchtet. Zum Schluss kommt ein Fazit über die weitere Entwicklung der VIA mit Überlegungen für Verbesserungen und Optimierungen