Electrotactile feedback applications for hand and arm interactions: A systematic review, meta-analysis, and future directions

Haptic feedback is critical in a broad range of human-machine/computer-interaction applications. However, the high cost and low portability/wearability of haptic devices remain unresolved issues, severely limiting the adoption of this otherwise promising technology. Electrotactile interfaces have the advantage of being more portable and wearable due to their reduced actuators' size, as well as their lower power consumption and manufacturing cost. The applications of electrotactile feedback have been explored in human-computer interaction and human-machine-interaction for facilitating hand-based interactions in applications such as prosthetics, virtual reality, robotic teleoperation, surface haptics, portable devices, and rehabilitation. This paper presents a technological overview of electrotactile feedback, as well a systematic review and meta-analysis of its applications for hand-based interactions. We discuss the different electrotactile systems according to the type of application. We also discuss over a quantitative congregation of the findings, to offer a high-level overview into the state-of-art and suggest future directions. Electrotactile feedback systems showed increased portability/wearability, and they were successful in rendering and/or augmenting most tactile sensations, eliciting perceptual processes, and improving performance in many scenarios. However, knowledge gaps (e.g., embodiment), technical (e.g., recurrent calibration, electrodes' durability) and methodological (e.g., sample size) drawbacks were detected, which should be addressed in future studies.Comment: 18 pages, 1 table, 8 figures, under review in Transactions on Haptics. This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible.Upon acceptance of the article by IEEE, the preprint article will be replaced with the accepted versio

Enriching passive touch sensation on flat surfaces using visual feedback

While human computer interaction has evolved around touch interaction a lot in recent years, it's been lacking any haptic feedback from the very beginning. Nowadays, devices using touch interaction all to do on a flat surface, using either a projection of digital contents or a touch screen. Since haptic feedback is an important factor in human surface perception, people have tried various ways to simulate haptic feedback even on completely flat surfaces. One of these ways is electrotacile feedback, which has mostly been used to simulate surface properties on active touch where the user has to move their finger over the surface in order to feel the haptic sensation. Previous research shows that vision is also a very important factor in surface perception and proprioception in general. We conducted a user study to investigate the influence of visual feedback on passive touch using electrotactile feedback. We concentrated on simulating depth instead of roughness which doesn't word particularly well for passive touch. We found that even though both electrotactile and visual feedback work well for depth or softness if applied individually, as soon as we presented our study subjects a condition with both feedback types, they did not repond to it anymore.Während sich die Mensch-Computer-Interaktion in den letzten Jahren stark um Touch-Interaktion entwickelt hat, hat dieser Interaktion von Anfang an jegliche Form des haptischen Feedbacks gefehlt. Heutzutage nuten alle touchfähigen Gerate flache Displays oder Projektionen von digitalen Inhalten auf flache Oberflächen. Da haptisches Feedback ein wichtiger Faktor der menschlichen Oberflächenwahrnehmung ist wurden schon viele Wege erforscht um haptisches Feedback auf komplett flachen Oberflächen zu simulieren. Eine dieser Wege ist elektrotaktiles Feedback was bisher hauptsächlich benutzt wurde um Oberflächeneigenschaften bei aktiver Berührung zu simulieren, also bei einem sich bewegenden Finger auf der Oberfläche. Vorige Studien zeigen auch, dass Visuelle Reize ein wichtiger Faktor bei der Oberflächenwahrnehmung sind und sogar die Wahrnehmung im Generellen dominieren. Wir haben eine Benutzerstudie durchgeführt um den Einfluss von visuellem Feedback auf passive Berührungen mit elektrotaktilem Feedback zu bestimmen. Wir haben und auf die Simulaton von Tiefe statt Rauhheit konzentriert, was schlecht mit passiven Berührungen funktioniert. Unsere Studie hat gezeigt dass obwohl das elektrotaktile und das visuelle Feedback alleine gut funktionieren um Weichheit oder Tiefe zu simulieren, beide Feedbackarten zusammen keine signifikanten Unterschiede erzielen

Electrotactons: designing and evaluating electrotactile cues

Electrotactile feedback is a novel haptic feedback modality that can be used to evoke a desired level of alertness and emotion or convey multidimensional information to the user. However, there is a lack of research investigating its basic design parameters and how they can be used to create effective tactile cues. This thesis investigates the effect of Electrotactile feedback on the subjective perception of specific sensations, such as urgency, annoyance, valence and arousal, to find the number of distinguishable levels in each sensation. These levels are then used for designing structured, abstract, electrotactile messages called Electrotactons. These have potential benefits over vibration-based cues due to the greater flexibility of the actuators. Experiments 1, 2 & 4 investigated the effects of manipulating the basic electrotactile parameters pulse width, amplitude and pulse frequency on perceived sensations. The results showed that all parameters have a significant effect on the perceived sensations, except for pulse frequency not having an effect on valence. Also, pulse frequencies of 30 PPS and above did not influence the perceived sensations. Experiment 3 investigated the use of pulse width, amplitude and pulse frequency to convey three types of information simultaneously encoded into an electrotactile cue. This was the first attempt to design Electrotactons using the basic parameters of electrotactile feedback. The results showed overall recognition rates of 38.19% for the complete Electrotactons. For the individual component parameters, pulse width had a recognition rate of 71.67%, amplitude 70.27%, and pulse frequency 66.36%. Experiment 5 investigated intensity and pulse frequency to determine how many distinguishable levels could be perceived. Results showed that both intensity and pulse frequency significantly affected perception, with four distinguishable levels of intensity and two of pulse frequency. Experiment 6 investigated the use of intensity and pulse frequency from in Experiment 5 to improve the design of Electrotactons on three body locations using two different size electrodes. The results showed overall recognition rates of up to 65.31% for the complete Electrotactons. For the individual component parameters, intensity had a recognition rate of 68.68%, and pulse frequency 94.41%. These results add significant new knowledge about the parameter space of electrotactile cue design and help designers select suitable properties to use when creating electrotactile cues

A hybrid haptic stimulation prosthetic wearable device to recover the missing sensation of the upper limb amputees

A hybrid haptic feedback stimulation system that is capable in sensing the contact pressure, the surface texture, and the temperature, simultaneously, was designed for a prosthetic hand to provide a tactile sensation to amputation patients. In addition, the haptic system was developed to enable the prosthetic’s users to implement withdrawal reflexes due to the thermal noxious stimulus in a quick manner. The re-sensation is achieved by non-invasively stimulating the skin of the patients’ residual limbs, based on the type and the level of tactile signals provided by the sensory system of the prostheses. Accordingly, three stages of design and development were performed to satisfy the research methodology. A vibrotactile prosthetic device, which is designed for the detection of contact pressure and surface texture in upper extremity, represents. While, the design of a novel wearable hybrid pressure-vibration haptic feedback stimulation device for conveying the tactile information regarding the contact pressure between the prosthetic hand and the grasped objects represents the second methodology stage. Lastly, the third stage was achieved by designing a novel hybrid pressure-vibration-temperature feedback stimulation system to provide a huge information regarding the prostheses environment to the users without brain confusing or requiring long pre-training. The main contribution of this work is the development and evaluation of the first step of a novel approach for a lightweight, 7 Degrees-Of-Freedom (DOF) tactile prosthetic arm to perform an effective as well as fast object manipulation and grasping. Furthermore, this study investigates the ability to convey the tactile information about the contact pressure, surface texture, and object temperature to the amputees with high identification accuracy by mean of using the designed hybrid pressure-vibration-temperature feedback wearable device. An evaluation of sensation and response has been conducted on forty healthy volunteers to evaluate the ability of the haptic system to stimulate the human nervous system. The results in term of Stimulus Identification Rate (SIR) show that all the volunteers were correctly able to discriminate the sensation of touch, start of touch, end of touch, and grasping objects. While 94%, 96%, 97%, and 95.24% of the entire stimuli were successfully identified by the volunteers during the experiments of slippage, pressure level, surface texture, and temperature, respectively. The position tracking controller system was designed to synchronize the movements of the volunteers’ elbow joints and the prosthetic’s elbow joint to record the withdrawal reflexes. The results verified the ability of the haptic system to excite the human brain at the abnormal noxious stimulus and enable the volunteers to perform a quick withdrawal reflex within 0.32 sec. The test results and the volunteers' response established evidence that amputees are able to recover their sense of the contact pressure, the surface texture, and the object temperature as well as to perform thermal withdrawal reflexes using the solution developed in this work

Head-mounted Sensory Augmentation System for Navigation in Low Visibility Environments

Sensory augmentation can be used to assist in some tasks where sensory information is limited or sparse. This thesis focuses on the design and investigation of a head-mounted vibrotactile sensory augmentation interface to assist navigation in low visibility environments such as firefighters’ navigation or travel aids for visually impaired people. A novel head-mounted vibrotactile interface comprising a 1-by-7 vibrotactile display worn on the forehead is developed. A series of psychophysical studies is carried out with this display to (1) determine the vibrotactile absolute threshold, (2) investigate the accuracy of vibrotactile localization, and (3) evaluate the funneling illusion and apparent motion as sensory phenomena that could be used to communicate navigation signals. The results of these studies provide guidelines for the design of head-mounted interfaces. A 2nd generation head-mounted sensory augmentation interface called the Mark-II Tactile Helmet is developed for the application of firefighters’ navigation. It consists of a ring of ultrasound sensors mounted to the outside of a helmet, a microcontroller, two batteries and a refined vibrotactile display composed of seven vibration motors based on the results of the aforementioned psychophysical studies. A ‘tactile language’, that is, a set of distinguishable vibrotactile patterns, is developed for communicating navigation commands to the Mark-II Tactile Helmet. Four possible combinations of two command presentation modes (continuous, discrete) and two command types (recurring, single) are evaluated for their effectiveness in guiding users along a virtual wall in a structured environment. Continuous and discrete presentation modes use spatiotemporal patterns that induce the experience of apparent movement and discrete movement on the forehead, respectively. The recurring command type presents the tactile command repeatedly with an interval between patterns of 500 ms while the single command type presents the tactile command just once when there is a change in the command. The effectiveness of this tactile language is evaluated according to the objective measures of the users’ walking speed and the smoothness of their trajectory parallel to the virtual wall and subjective measures of utility and comfort employing Likert-type rating scales. The Recurring Continuous (RC) commands that exploit the phenomena of apparent motion are most effective in generating efficient routes and fast travel, and are most preferred. Finally, the optimal tactile language (RC) is compared with audio guidance using verbal instructions to investigate effectiveness in delivering navigation commands. The results show that haptic guidance leads to better performance as well as lower cognitive workload compared to auditory feedback. This research demonstrates that a head-mounted sensory augmentation interface can enhance spatial awareness in low visibility environments and could help firefighters’ navigation by providing them with supplementary sensory information

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