IEEE Transactions on Haptics最新文献

Teleoperating mobile manipulators can be cognitively demanding due to a lack of depth perception and situational awareness. While virtual fixture constraints can be used to improve teleoperation performance, it is critical to ensure safety of these fixtures in order to enable their use in physical human-robot-interaction (pHRI) tasks. In this work, we propose to use control barrier functions (CBF) to design a virtual fixture architecture that allows us to tune the tradeoff between performance and safety. We design the architecture to ensure tracking performance between the user and robot is maintained outside of virtual fixture violations, and to simultaneously ensure that the robot cannot overshoot into a constraint. We conducted an analysis to investigate the relationship between tracking and safety, and present results which indicate that the ratio between the control gain used for tracking and the safety decay rate determine when the CBF filter and CBF-based force feedback become active. Finally, we implemented our proposed virtual fixture architecture on a mobile manipulator platform to investigate its effects on user's performance as they performed a simulated temperature scanning task. Overall, this work highlights the potential benefits of using CBF-based haptic virtual fixtures for conducting pHRI tasks.

Illusory pulling sensations, induced by asymmetric vibrations applied to the fingertips, have attracted attention as a means to investigate sensorimotor processing and develop haptic interfaces. In addition, sensitivity to the illusory pulling sensation tended to decline in some older female participants, suggesting that factors related to aging and/or gender difference may be involved in this phenomenon. In this study, we aimed to clarify the contribution of somatosensory and cognitive functions to the illusory pulling sensation, focusing on aging and gender difference to examine these contributions. Sixty older participants aged 63 to 80 years (30 males, 30 females) completed seven assessments, covering sensitivity to the illusory pulling sensation and a range of somatosensory and cognitive functions from vibration detection thresholds to general cognitive ability assessed by the Mini-Mental State Examination (MMSE). Consistent with prior findings, older females exhibited significantly lower sensitivity to the illusion. Interestingly, although gender differences were observed in some of the assessment items, such as hand length and performance on the parallel-setting task, none of these factors mediated the gender effect on the illusion. While age itself did not have a direct effect on the illusion, an indirect effect was observed through general cognitive function as assessed by the MMSE. These findings suggest that the illusory pulling sensation tends to weaken not only with aging, but also particularly when aging is accompanied by cognitive decline. Overall, gender and cognitive function may play key roles in individual differences in the illusory pulling sensation.

Wearable haptic gloves have the potential to greatly enhance active touch experiences in virtual reality (VR). However, it remains unclear how well people can interpret glove-enabled virtual touch experiences when experienced passively (for example, when they passively view a virtual hand perform autonomous actions while also feeling what the virtual hand feels via a haptic glove). Such a "haptic replay" scenario could enable people to share, revisit, or demonstrate touch-critical experiences, including medical palpation or fine manipulation of tools. This study explores a virtual user's ability to interpret one tactile feature, object size, when receiving touch feedback from a commercial haptic glove during either an active or passive grasp interaction. Although passive conditions resulted in poorer size acuity than during active touch, passive performance improved when participants mimicked the motion of the virtual hand, underscoring the role of proprioceptive feedback in grasp interpretation. Additionally, gender differences in performance suggest potential influences of glove ergonomics and size congruency between the real and virtual hand. Future research should investigate these variables and strive for balanced gender representation to assess generalization across VR applications.

We present a customizable soft haptic system that integrates modular hardware with an information-theoretic algorithm to personalize feedback for different users and tasks. Our platform features modular, multi-degree-of-freedom pneumatic displays, where different signal types - such as pressure, frequency, and contact area - can be activated or combined using fluidic logic circuits. These circuits simplify control by reducing reliance on specialized electronics and enabling coordinated actuation of multiple haptic elements through a compact set of inputs. Our approach allows rapid reconfiguration of haptic signal rendering through hardware-level logic switching, without rewriting code. Personalization of the haptic interface is achieved through the combination of modular hardware and software-driven signal selection. To determine which display configurations will be most effective, we model haptic communication as a signal transmission problem, where an agent must convey latent information to the user. We formulate the optimization problem to identify the haptic hardware setup that maximizes the information transfer between the intended message and the user's interpretation, accounting for individual differences in sensitivity, preferences, and perceptual salience. We evaluate this framework through user studies where participants interact with reconfigurable displays under different signal combinations. Our findings support the role of modularity and personalization in creating multimodal haptic interfaces and advance the development of reconfigurable systems that adapt with users in dynamic human-machine interaction contexts.

Vibrotactile actuators are used in many different haptic devices, e.g. game controllers and smartphones. These vibrotactile actuators are typically made of rigid materials. In this paper, we use soft pneumatic actuators known as Pneumatic Unit Cell (PUC) to characterize the perceived intensity of vibrotactile stimuli when presented at the tip of the index finger. This study investigates how three parameters-stimulus pressure (4 to 30 kPa), inflation-deflation frequency (20 to 100 Hz), and actuator stiffness (determined by top layer thicknesses of 0.9 mm and 1.2 mm)-influence the perceptual intensity of the stimuli. Psychophysical experiments involving 16 participants were conducted using the AEPsych toolbox. These reveal that all the three parameters - pressure, frequency, and actuator stiffness significantly affect perceptual intensity. The findings indicate that both pressure and frequency exhibit a positive main effect and a positive interaction effect on perceived vibrotactile intensity. Additionally, the results show that, for a given frequency, pressure variations produce more perceptually distinct stimuli than frequency variations for a given pressure. Finally, presenting vibrotactile stimuli on a less stiff PUC actuator was perceived as being less intense than when the same stimulus was presented on a stiffer PUC actuator. Overall, this study provides key insights into the combined influence of pressure, frequency and actuator stiffness on the perceived vibrotactile intensity.

Affective touch has attracted significant interest due to its positive effects on child development and adult well-being. Studies showed that light and slow stroke of soft brush on hairy skin elicits affective sensation by activating C-Tactile fibers. Mid-air haptics, which uses focused ultrasound to create tactile sensations in free space, offers a promising method for eliciting affective changes. However, it remains poorly understood to what extent mid-air haptics can produce the perception similar to a brush stroke on hairy skin. Here, we conducted a psychophysical study comparing the tactile perception of mid-air ultrasound stimulation with that of real materials (sandpaper, aluminum resin, urethane rubber, cloth, and soft brush). Participants rated each stimulation on the dorsum of hand along three affective touch dimensions (pleasantness, surprise, ticklishness) and three discriminative touch dimensions (smoothness, softness, warmness). Univariate analyses revealed that ultrasound stimuli differed from aluminum resin, sandpaper, and urethane rubber in one or more dimensions of discriminative touch. Ultrasound stimulation with 10 Hz amplitude modulation significantly felt more pleasant than sandpaper, while no consistent differences between ultrasound and real textures ratings was observed in surprise and ticklishness. Multivariate analyses showed that ultrasound stimuli with amplitude modulation at 10 Hz and 100 Hz were significantly closer to real textures than unmodulated ultrasound. Questionnaires showed that over half of the participants identified ultrasound stimulation as a brush or cotton. These findings suggest that mid-air haptics can evoke perceptual attributes overlapping with those of real textures, including soft brushes, on hairy skin. Moreover, amplitude modulation may enhance the perceptual resemblance to realistic textures.

Research in affective touch often utilizes a pleasant stroking paradigm, with touch typically delivered at velocities between 0.3-30 cm/s and forces about 0.4 N. These values are derived from perceptual and physiological responses of touch receivers rather than natural behaviors of touchers. Herein, we observe untrained touchers in delivering pleasant touch as gentle strokes to a receiver's forearm through high-resolution force and position measurement using an instrumented brush. Twenty participants delivered about eleven strokes in each of five trials, yielding data on stroke velocity, force, duration, and length. The cohort deployed forces (0.37 N ± 0.24, 2 SD) near 0.4 N, but stroking velocities (13.7 cm/s ± 8.8, 2 SD) slightly higher than typically considered "optimal" (1-10 cm/s). We observed no correlation between stroke force and velocity, which led us to consider these factors jointly in characterizing an individual's brushing strategy. Moreover, while the cohort of participants exhibited a compact range of forces and velocities, individuals tended to occupy only subsets of this range with high repeatability across trials. Altogether, the findings suggest a need to further evaluate the velocity range between 10-30 cm/s and to jointly consider force, velocity, and consistency in characterizing an individual's brushing strategy.

Rapid advances in engineering and materials science have introduced new possibilities for fabricating passive haptic interfaces such as tactile maps. This study proposes a dual-aspect evaluation methodology-based on user experience and production efficiency-to assess 12 tactile map production techniques, including additive manufacturing methods (e.g., SLA, UV printing), casting (epoxy resin, silicone), CNC milling, and paper-based techniques (e.g., swell-paper, TIGER). The user experience aspect includes spatial localization tasks, semantic differential ratings, and user rankings conducted with 21 people with visual impairments. It captures tactile comfort, symbol legibility, and perceptual clarity during 90-minute sessions using custom-designed pseudomaps. The production efficiency aspect considers cost, complexity, durability (including weather resistance), and versatility in reproducing hybrid - tactile and graphic content. Results showed that paper-based techniques offered high tactile comfort but lower spatial accuracy, legibility, and durability. In contrast, PolyJet and UV printing scored highest overall by balancing perceptual performance and practical production attributes. Several techniques-including UV printing and PolyJet-were evaluated for tactile map production for the first time. Our methodology is modular and adaptable: weights can be adjusted to prioritize specific application needs, such as cost-efficiency or outdoor durability. A case study involving tactile maps of historic gardens demonstrates the framework's utility in real-world use cases. This work contributes to the design and evaluation of passive haptic interfaces by providing a replicable tool for comparing tactile rendering methods across diverse material and perceptual dimensions.

Virtual mass simulation is one of the recent topics in the field of haptic devices (HDs), which can alter the apparent mass of the HD. Simulating negative values of virtual mass leads to a decrease in the apparent effective mass, improving transparency but weakening stability. Positive virtual mass rendering increases the apparent mass, reduces transparency, and enhances stability. This paper analyzes the stability of a haptic device while simulating a virtual environment consisting of a mass, spring, and damper in the presence of a constant time delay. The results are closed-form equations that can predict the stability boundary for small and even large values of virtual damping and time delay. These closed-form equations demonstrate that the maximum renderable virtual mass is twice the physical mass of the HD, and the minimum value equals its negative; both occur in the case of zero time delay. Increasing the time delay reduces both the minimum and maximum values of the renderable virtual mass. The study also shows that using virtual mass can improve the maximum value of a renderable virtual spring. The equations show that, in the absence of delay, properly tuning the virtual mass and virtual damping can enlarge the maximum renderable stiffness by up to 5.8 times in theory. In the experiments under time delay, the stiffness increased by a factor of 3.5, compared to the theoretical prediction of 4.1 times. The results further reveal situations where a nonzero minimum stiffness is required for stability. All findings are validated via simulations and experiments on a dedicated test bed.