IEEE Transactions on Haptics最新文献

Wearable haptic devices provide touch feedback to users for applications including virtual reality, prosthetics, and navigation. When these devices are designed for experimental validation in research settings, they are often highly specialized and customized to the specific application being studied. As such, it can be difficult to replicate device hardware due to the associated high costs of customized components and the complexity of their design and construction. In this work, we present Snaptics, a simple and modular platform designed for rapid prototyping of fully wearable multi-sensory haptic devices using 3D-printed modules and inexpensive off-the-shelf components accessible to the average hobbyist. We demonstrate the versatility of the modular system and the salience of haptic cues produced by wearables constructed with Snaptics modules in two human subject experiments. First, we report on the identification accuracy of multi-sensory haptic cues delivered by a Snaptics device. Second, we compare the effectiveness of the Snaptics Vibrotactile Bracelet to the Syntacts Bracelet, a high-fidelity wearable vibration feedback bracelet, in assisting participants with a virtual reality sorting task. Results indicate that participant performance was comparable in perceiving cue sets and in completing tasks when interacting with low-cost Snaptics devices as compared to a similar research-grade haptic wearables.

Tactile feedback is essential for upper-limb prostheses functionality and embodiment, yet its practical implementation presents challenges. Users must adapt to non-physiological signals, increasing cognitive load. However, some prosthetic devices transmit tactile information through socket vibrations, even to untrained individuals. Our experiments validated this observation, demonstrating a user's surprising ability to identify contacted fingers with a purely passive, cosmetic hand. Further experiments with advanced soft articulated hands revealed decreased performance in tactile information relayed by socket vibrations as hand complexity increased. To understand the underlying mechanisms, we conducted numerical and mechanical vibration tests on four prostheses of varying complexity. Additionally, a machine-learning classifier identified the contacted finger based on measured socket signals. Quantitative results confirmed that rigid hands facilitated contact discrimination, achieving 83% accuracy in distinguishing index finger contacts from others. While human discrimination decreased with advanced hands, machine learning surpassed human performance. These findings suggest that rigid prostheses provide natural vibration transmission, potentially reducing the need for tactile feedback devices, which advanced hands may require. Nonetheless, the possibility of machine learning algorithms outperforming human discrimination indicates potential to enhance socket vibrations through active sensing and actuation, bridging the gap in vibration-transmitted tactile discrimination between rigid and advanced hands.

This study presents the characterization and validation of the VIBES, a wearable vibrotactile device that provides high-frequency tactile information embedded in a prosthetic socket. A psychophysical characterization involving ten able-bodied participants is performed to compute the Just Noticeable Difference (JND) related to the discrimination of vibrotactile cues delivered on the skin in two forearm positions, with the goal of optimising vibrotactile actuator position to maximise perceptual response. Furthermore, system performance is validated and tested both with ten able-bodied participants and one prosthesis user considering three tasks. More specifically, in the Active Texture Identification, Slippage and Fragile Object Experiments, we investigate if the VIBES could enhance users' roughness discrimination and manual usability and dexterity. Finally, we test the effect of the vibrotactile system on prosthetic embodiment in a Rubber Hand Illusion (RHI) task. Results show the system's effectiveness in conveying contact and texture cues, making it a potential tool to restore sensory feedback and enhance the embodiment in prosthetic users.

Virtual damping is often employed to improve stability in virtual environments, but it has previously been found to bias perception of stiffness, with its effects differing when it is introduced locally within a wall/object or globally in both the wall and in freespace. Since many potential applications of haptic rendering involve not only comparisons between two environments, but also the ability to recognize rendered environments as belonging to different categories, it is important to understand the perceptual impacts of freespace and wall damping on stiffness classification ability. This study explores the effects of varying levels of freespace and wall damping on users' ability to classify virtual walls by their stiffness. Results indicate that freespace damping improves wall classification if the walls are damped, but will impair classification of undamped walls. These findings suggest that, in situations where users are expected to recognize and classify various stiffnesses, freespace damping can be a factor in narrowing or widening gaps in extended rate-hardness between softer and stiffer walls.

Existing market-available refreshable Braille displays (RBDs) offer limited functionality at a high cost, hindering accessibility for individuals with blindness and visual impairment for teaching and learning purposes. This motivates us to develop a multi-functional, compact, and affordable RBD tailored for educational institutes to enhance teaching and learning experiences. We propose the development of BLISS (Braille Letters and Interactive Shape Screen), a novel RBD, that BLISS presents a unique configuration arrangement of Braille cells that accommodates up to six letters at a time and shapes by reusing the Braille pins. To determine the optimal specifications, including size, Braille cell spacing, and pin configuration, we fabricated and evaluated 3D-printed sets, mimicking how BLISS would display letters and shapes. We tested 36 variants of 3D-printed sets with 8 individuals with blindness and visual impairment and found that conventional Braille spacing is insufficient for accurately representing shapes. Hence, BLISS will introduce a novel design that uses a pin configuration to raise the extra pins to present shapes and lower them for Braille letters, providing dual-mode operation. Our findings show the potential of BLISS to display both Braille letters and shapes on the same refreshable display, offering a novel, compact, and cost-effective solution.

Welding is an important operation in many industries, including construction and manufacturing, which requires extensive training and practices. Although welding simulators have been used to accommodate welding training, it is still challenging to enable novice trainees to effectively understand the kinesthetic experience of the expert in an egocentric manner, such as the proper way of force exertion in complex welding operations. This study implements a robot-assisted perceptual learning system to transfer the expert welders' experience to trainees, including both the positional and force control actions. A human-subject experiment (N = 30) was performed to understand the motor skill acquisition process. Three conditions (control, robotic positional guidance with force visualization, and force perceptual learning with position visualization) were tested to evaluate the role of robotic guidance in welding motion control and force exertion. The results indicated various benefits related to task completion time and force control accuracy under the robotic guidance. The findings can inspire the design of future welding training systems enabled by external robotic systems.

The movement-related cortical potential (MRCP) is a low-frequency component of the electroencephalography (EEG) signal that originates from the motor cortex and surrounding cortical regions. As the MRCP reflects both the intention and execution of motor control, it has the potential to serve as a communication interface between patients and neurorehabilitation robots. In this study, we investigated the EEG signal recorded centered at the Cz electrode with the aim of decoding four rates of force development (RFD) during isometric contractions of the tibialis anterior muscle. The four levels of RFD were defined with respect to the maximum voluntary contraction (MVC) of the muscle as follows: Slow (20% MVC/s), Medium (30% MVC/s), Fast (60% MVC/s), and Ballistic (120% MVC/s). Three feature sets were assessed for describing the EEG traces in the classification process. These included: (i) MRCP Morphological Characteristics in the δ-band, such as timing and amplitude; (ii) MRCP Statistical Characteristics in the δ-band, such as standard deviation, mean, and kurtosis; and (iii) Wideband Time-frequency Features in the 0.1-90 Hz range. The four levels of RFD were accurately classified using a support vector machine. When utilizing the Wideband Time-frequency Features, the accuracy was 83% ± 9% (mean ± SD). Meanwhile, when using the MRCP Statistical Characteristics, the accuracy was 78% ± 12% (mean ± SD). The analysis of the MRCP waveform revealed that it contains highly informative data on the planning, execution, completion, and duration of the isometric dorsiflexion task. The temporal analysis emphasized the importance of the δ-band in translating to motor command, and this has promising implications for the field of neural engineering systems.

Combining or integrating information from multiple senses often provides richer and more reliable estimates for the perception of objects and events. In daily life, sensory information from the same source often is in close spatiotemporal proximity. This can be an important determinant of whether and how multisensory signals are combined. The introduction of advanced technical display systems allows to present multisensory information in virtual environments. However, technical displays can lack the spatiotemporal fidelity of the real world due the rendering delays. Thus, any spatiotemporal incongruency could alter how information is combined. In the current study we tested this by investigating if and how spatially and temporally discrepant tactile displacement cues can supplement imprecise visual displacement cues. Participants performed a visual displacement task with visual and tactile displacement cues under spatial and temporal incongruency conditions. We modelled how participants combined visual and tactile information in visuotactile condition using their performance in visual only condition. We found that temporal incongruency lead to an increase in tactile weights although they were correlated with the congruency condition. In contrast, the spatial incongruency led to individual differences altering cue combination strategies. Our results illustrate the importance of spatiotemporal congruency for combining tactile and visual cues when making visual displacement judgments. Given the altered cue combination strategies and individual differences, we recommend developers to adopt individual spatiotemporal calibration procedures to improve the efficiency of the sensory augmentation.

Restoring tactile feedback in virtual reality can improve user experience and facilitate the feeling of embodiment. Electrotactile stimulation can be an attractive technology in this context as it is compact and allows for high-resolution spatially distributed stimulation. In the present study, a 32-channel tactile glove worn on the fingertips was used to provide tactile sensations during a virtual version of a rubber hand illusion experiment. To assess the benefits of multichannel stimulation, we modulated the spatial extent of feedback and its fidelity. Thirty-six participants performed the experiment in two conditions, in which stimulation was delivered to a single finger or all fingers, and three tactile stimulation types within each condition: no tactile feedback, simple single-point stimulation, and complex sliding stimulation mimicking the movements of the brush. Following each trial, the participants answered a multi-item embodiment questionnaire and reported the proprioceptive drift. The results confirmed that modulating the spatial extent of stimulation, from a single finger to all fingers, was indeed a successful strategy. When stimulating all fingers, tactile stimulation significantly improved all subjective measures compared to receiving no tactile stimulation. However, unexpectedly, the second strategy, that of modulating the fidelity of feedback, was not successful since there was no difference between the simple and complex tactile feedback in any of the measures. The results, therefore, imply that the effects of tactile feedback are better expressed in a more dynamic scenario (i.e., making/breaking contact and delivering stimulation to different body locations), while it still needs to be investigated if further improvements of the complex feedback can make it more effective compared to the simple approach.