Recent hand tracking systems have contributed to enhancing user experience in the virtual environment (VE) due to its natural and intuitive interaction. In addition, wearable haptic devices are another approach to provide engaging and immersive experiences. However, controllers are still prevalent in VR (Virtual Reality) games as a main interaction device. Also, haptic devices are rare and not widely accepted by users because they get bulky to implement sophisticated haptic sensation. To overcome this issue, I conducted experiments (Study 1 and Study 2 of this Thesis) to investigate the effect of interaction method (controller and whole-hand interaction using hand tracking) and vibrotactile feedback on user experience in the VR game. In Study 1 of this Thesis, I recruited 36 participants and compared the user's sense of presence, engagement, usability, and task performance under three different conditions: (1) VR controllers, (2) hand tracking without vibrotactile feedback, and (3) hand tracking with vibrotactile feedback at fingertips through the gloves I developed. The gloves deliver vibrotactile feedback at each fingertip by vibration motors. I observed that whole-hand interaction using hand tracking enhanced the user's sense of presence, engagement, usability, and task performance. Further vibrotactile feedback increased the presence and engagement more clearly. Based on the participants' feedback, I could further modify the form factor to make it more usable in the VR game and comfortable to wear on a regular basis. In this sense, in Study 2 of this Thesis, I developed a new thimble-shape device to deliver vibrotactile feedback only at one fingertip rather than ten fingertips. Further, social VR is an emerging VR platform where multiple users can interact with one another. However, most social VR applications have not provided a sense of touch. I recruited 24 participants and conducted an experiment that explored the effects of interaction method and fingertip vibrotactile feedback on the user's sense of social presence, presence, engagement, and task performance in a cooperative VR game under four different conditions: (1) VR controllers without vibrotactile feedback, (2) VR controllers with vibrotactile feedback, (3) hand tracking without vibrotactile feedback, and (4) hand tracking with vibrotactile feedback with the fingertip vibrotactile device. The results showed that whole-hand interaction using hand tracking increased the level of presence. In addition, multiple items in the presence questionnaire indicated that vibrotactile feedback enhanced the level of presence as well. However, I could not observe the significant difference in social presence due to the unique setting of this experiment. Unlike the previous studies, my task was sufficiently cooperative, and thus, the participants felt high level of social presence regardless the conditions, which led to the ceiling effect. I also observed that there was no significant difference in engagement. Controller conditions had higher performance than hand tracking due to the technological limitations in hand tracking. Results are discussed in terms of implications for the components of interaction in the VR with hands, a touch in social VR, cooperative VR game, and practical design guidelines. / Master of Science / Recent hand tracking systems have contributed to enhancing user experience in the virtual environment (VE) due to its natural and intuitive interaction. In addition, wearable haptic devices are another approach to provide engaging and immersive experiences. However, controllers are still prevalent in VR (Virtual Reality) games as a main interaction device. Also, haptic devices are rare and not widely accepted by users because they get bulky to implement sophisticated haptic sensation. To overcome this issue, I conducted experiments (Study 1 and Study 2 of this Thesis) to investigate the effect of interaction method (controller and whole-hand interaction using hand tracking) and vibrotactile feedback on user experience in the VR game. In Study 1 of this Thesis, I recruited 36 participants and compared the user's sense of presence, engagement, usability, and task performance under three different conditions: (1) VR controllers, (2) hand tracking without vibrotactile feedback, and (3) hand tracking with vibrotactile feedback at fingertips through the gloves I developed. The gloves deliver vibrotactile feedback at each fingertip by vibration motors. I observed that whole-hand interaction using hand tracking enhanced the user's sense of presence, engagement, usability, and task performance. Further vibrotactile feedback increased the presence and engagement more clearly. Based on the participants' feedback, I could further modify the form factor to make it more usable in the VR game and comfortable to wear on a regular basis. In this sense, in Study 2 of this Thesis, I developed a new thimble-shape device to deliver vibrotactile feedback only at one fingertip rather than ten fingertips. Further, social VR is an emerging VR platform where multiple users can interact with one another. However, most social VR applications have not provided a sense of touch. I recruited 24 participants and conducted an experiment that explored the effects of interaction method and fingertip vibrotactile feedback on the user's sense of social presence, presence, engagement, and task performance in a cooperative VR game under four different conditions: (1) VR controllers without vibrotactile feedback, (2) VR controllers with vibrotactile feedback, (3) hand tracking without vibrotactile feedback, and (4) hand tracking with vibrotactile feedback with the fingertip vibrotactile device. The results showed that whole-hand interaction using hand tracking increased the level of presence. In addition, multiple items in the presence questionnaire indicated that vibrotactile feedback enhanced the level of presence as well. However, I could not observe the significant difference in social presence due to the unique setting of this experiment. Unlike the previous studies, my task was sufficiently cooperative, and thus, the participants felt high level of social presence regardless the conditions, which led to the ceiling effect. I also observed that there was no significant difference in engagement. Controller conditions had higher performance than hand tracking due to the technological limitations in hand tracking. Results are discussed in terms of implications for the components of interaction in the VR with hands, a touch in social VR, cooperative VR game, and practical design guidelines.

Vibrotactile feedback offers a unique opportunity to augment or reconstruct impaired tactile sensations, whether that be in the form of enhancing prosthetics or specialized protective clothing. Important information about temperature and object slippage serve to endanger the human operator or equipment. This thesis presents three experiments which investigate amplitude modulated vibrotactile signals as a scalar dimension of roughness, the effect those signals and their locations (finger pad, forearm, bicep) have on the performance of two tasks: the sensing of temperatures simulated by vibrotactile signals and gripping an object of simulated surface texture. The results show task performance increase when the feedback and site of action are co-located for sensory tasks and decrease for manipulatory tasks.

Following lower-limb amputation, patients suffer from sensory loss within the prosthesis/residuum complex leading to diminished proprioception and balance. Artificial sensory systems have the potential to improve rehabilitation outcomes including better functional usage of lower-limb prostheses to achieve a higher quality of life for the prosthetic users. The purpose of this work was to develop and test the e fficacy of a vibrotactile feedback system for lower-limb amputees that may augment feedback during complex balance and movement tasks. Responses to different vibrotactile stimuli frequencies, locations, and physical conditions were assessed. Key outcome measures for this work were the response time and response accuracy of the subjects to the different stimulator configurations. Frequencies closer to 250 Hz applied to the anterior portion of the thigh resulted in the quickest reaction times. When multitasking, reaction times increased. These preliminary results indicate that vibrotactile sensory feedback may be viable to use by lower-limb amputees.

Following lower-limb amputation, patients suffer from sensory loss within the prosthesis/residuum complex leading to diminished proprioception and balance. Artificial sensory systems have the potential to improve rehabilitation outcomes including better functional usage of lower-limb prostheses to achieve a higher quality of life for the prosthetic users. The purpose of this work was to develop and test the e fficacy of a vibrotactile feedback system for lower-limb amputees that may augment feedback during complex balance and movement tasks. Responses to different vibrotactile stimuli frequencies, locations, and physical conditions were assessed. Key outcome measures for this work were the response time and response accuracy of the subjects to the different stimulator configurations. Frequencies closer to 250 Hz applied to the anterior portion of the thigh resulted in the quickest reaction times. When multitasking, reaction times increased. These preliminary results indicate that vibrotactile sensory feedback may be viable to use by lower-limb amputees.

This study was conducted to assess physical and perceptual properties of a tactile display for a vibrotactile notification system within the CIRMMT Live Electronics Framework (CLEF), a Max-based modular environment for composition and performance of live electronic music. The tactile display was composed of two rotating eccentric mass actuators driven by a PWM signal generated from an Arduino microcontroller. Physical measurements using an accelerometer were carried out in order to estimate intensity and spectral peak frequency as function of duty cycle of the PWM signal. In addition, three user-based studies were conducted to estimate perceptual vibrotactile absolute threshold, differential threshold and temporal differential threshold. Obtained results provided us with precise guidelines that facilitate the design of perceptually robust vibrotactile stimuli for our tactile application. A set of eight simple tactons (vibrotactile icons) was defined, whereafter an absolute identification test was conducted in order to estimate mean tacton recognition rates. Results were promising; mean tacton recognition rate was found to be 74 %. Based on all findings described above, a Max-based prototype used for exploration of tactile stimuli was developed. The prototype contained a library of tactile notification presets to be loaded into CLEF, along with a simple tacton editor for design of customized tactile events. / Syftet med denna studie var att undersöka fysiska och perceptuella egenskaper hos en taktil display som designats för att presentera taktila notifikationssignaler till användare av CIRMMT Live Electronics Framework (CLEF), en Max-baserad modulär miljö för komposition och framförande av musikstycken som involverar Live Electronics. Live Electronics är ett begrepp som innefattar elektronik som används för att generera, processera eller modifiera ljud i realtid. Den taktila display som användes i denna studie var uppbyggd av två roterande excentriska massor, drivna av en pulsbreddsmodulerad signal som genereras av en Arduino mikrokontroller. Accelerometermätningar och tre användarbaserade studier genomfördes för att undersöka följande: intensitet och spektral toppfrekvens som funktion av pulskvot, sensorisk tröskel och intensitetsdiskriminering mellan presenterade stimuli, samt JND i millisekunder för två efterföljande taktila stimuli. Erhållna resultat analyserades varefter riktlinjer för design av perceptuellt robusta signaler för vår taktila display sattes upp. I slutfasen av studien designades åtta taktila signaler, varefter en användarbaserad studie genomfördes för att uppskatta hur lätta dessa signaler var att identifiera. En genomsnittlig identifikationsnivå på 74 % kunde noteras. Baserat på ovan beskrivna resultat utvecklades slutligen en taktil modulprototyp i form av ett bibliotek av fördefinierade taktila stimuli. Denna prototyp inkluderande även en funktion som gav användaren möjlighet att designa och skräddarsy egna taktila signaler.

No description available.

The usefulness of vibrotactile feedback as a channel to communicate information has been widely recognized. However, most of the recent work on this subject uses actuators that are either too expensive or too large for many practical applications. This thesis explores the generation of vibrotacatile feedback patterns using a simple, inexpensive eccentric-mass motor that is constrained to use a constant voltage and a low on/off switching frequency. In particular, it explores the pulse timing method, which utilizes the slow transient response of the eccentric-mass motor to calculate pulse and rest times for an arbitrary envelope waveform shape. Several hardware tests were performed to (1) obtain a model of the transient response and (2) to verify that the resulting vibrations match the patterns predicted by the pulse timing method. Two custom built devices consisting of an eccentric-mass motor and a rigid housing were used in addition to a Wii remote. Vibrations for each device were measured and compared to the pattern predicted by the pulse timing method when the device was sitting on a table top and when the device was held in the hand. Results indicate that the vibrations match the predicted patterns very well in both cases. It was also determined that error in the motor's transient response model will result in some error between the measured and predicted vibrations. To assess whether this error affects perception of the intended envelope waveform, a study was performed in which users were asked to identify the envelope waveform of vibration patterns created using curve-fit models that contained various levels of error. An analysis of variance revealed that error in the curve-fit will have an effect on the perception of the envelope waveform if the error is large. Two more user studies were performed to determine the perceptual space of patterns generated using the pulse timing method, and to determine whether users could identify the meanings encoded within vibration features. The Perceptual Space study used a cluster-sorted Multi-Dimensional Scaling analysis to determine that envelope waveform, roughness (deviation from the envelope waveform), and amplitude are vibration features that may be used to encode information. Using these features, participants were presented with vibrations that contained GPS navigation instructions similar to those used in a car, and were asked to identify the associated meaning. Users were able to correctly identify all three features with an average accuracy of 80.6%, and were able to correctly identify the envelope waveform and roughness with accuracies of 96.9% and 94.5% respectively. These results are evidence that the pulse timing method (and eccentric-mass motors in general) are capable of generating complex vibrotactile feedback patterns that can be uniquely identified.

No description available.

There are different ways to interact with different hardware, therefore it is important to have an understanding about what factors that affect the experience when designing interactions and interfaces. This study focuses on exploring how auditory and vibrotactile feedback are perceived by the users when they interact in a virtual AR environment. An application was developed to the AR glasses Magic Leap with different interactions, both passive and active. An experimental study was conducted with 28 participants that got to interact in this virtual environment. The study included two parts. First the participants interacted in the virtual environment where they did a think aloud. Thereafter they were interviewed. There were a total of three test cases. One with only auditory feedback, one with vibrotactile feedback, and a third that had both auditory and vibrotactile feedback. Seven of the 28 participants acted as a control group that did not have any feedback to their interactions. The study shows that using only vibrotactile feedback creates different impressions depending on earlier experiences with the same AR environment. Using only auditory feedback created an atmosphere that were close to reality. Having both feedbacks active at the same time reduced the noticed feedback and some interactions were here not even noticed at all. Passive interactions were more noticed than active interactions in all cases. / Det finns flera olika sätt att interagera med olika hårdvaror och därför är det viktigt att ha en förståelse kring vilka faktorer som påverkar upplevelsen när man designar för diverse gränssnitt och interaktioner. Den här studien fokuserar på att utforska hur auditiv och vibrationsåterkoppling uppfattas av användaren när de interagerar i en virtuell AR-miljö. En applikation var utvecklad till AR-glasögonen Magic Leap One med olika aktiva och passiva interaktioner.En experimentell studie genomfördes med 28 deltagare som fick interagera i en virtuell miljö. Studien bestod av av två delar. Först fick deltagarna interagera i en virtuell miljö där de gjorde en think aloud. Efter detta blev de intervjuade. Det var totalt tre testfall, ett hade endast auditiv återkoppling, ett hade vibrationsåterkoppling och det sista hade både auditiv och vibrationsåterkoppling. Sju av de 28 deltagarna agerade kontrollgrupp och de hade ingen återkoppling på deras interaktioner.Studien visade att bara använda vibrationsåterkoppling skapade olika intryck beroende på de tidigare erfarenheterna i samma AR-miljö. Att endast använda auditiv återkoppling skapade en atmosfär som vara nära verkligheten. Att ha båda återkopplingarna aktiva samtidigt reducerade den totala märkta återkopplingen och några interaktioner hade inte någon person som noterade någon av dem. Passiva interaktioner var mer uppmärksammade än aktiva interaktioner i alla testfallen.

<p>Our study investigates how different mapping strategies of distance information affect performance in an object exploration task with a teleoperated virtual robot. The task was to find an object inside a backpack using a simulated robotic gripper. A virtual proximity sensor tracked the distance between the tip of the gripper and the object. The distance was conveyed as a vibration pattern on the users index finger. This is the only information that was received to guide the user towards the object. The goal was to locate the hidden object by moving the tip of the gripper as quickly and as closely towards the object as possible without touching it. We implemented three different mapping strategies that utilized continuous frequency and amplitude variations of sinusoidal vibrations to encode distance. The present study provides empirical evidence that the mapping strategy can affect accuracy when approaching an object. We found that linear feedback sensations help to sense the rate of approach. Non- linear feedback perception can provide cues that enable more accurate approximation of the absolute distance. We found that experienced participants could selectively attend to and integrate frequency and intensity cues when both modalities are changed simultaneously. Inexperienced participants were not able to make this distinction and found it difficult to interpret such a signal. They preferred one-dimensional changes.</p>