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High-spatial-resolution wearable tactile arrays have drawn interest from both industry and research, thanks to their capacity for delivering detailed tactile sensations. However, investigations of human tactile perception with high resolution tactile displays remain limited, primarily due to the high costs of multi-channel control systems and the complex fabrication required for fingertip-sized actuators. In this work, we introduce the Soft Haptic Display (SHD) toolkit, designed to enable students and researchers from diverse technical backgrounds to explore high-density tactile feedback in extended reality (XR), robotic teleoperation, braille displays, navigation aid, MR-compatible somatosensory stimulation, and remote palpation. The toolkit provides a rapid prototyping approach and real-time wireless control for a low-cost, 4×4 soft wearable fingertip tactile display with a spatial resolution of 4 mm. We characterized the display’s performance with a maximum vertical displacement of 1.8 mm, a rise time of 0.25 second, and a maximum refresh rate of 8 Hz. All materials and code are open-sourced to foster broader human tactile perception research of high-resolution haptic displays. 

(1) Background: The safe execution of heavy machinery operations and high-risk construction tasks requires operators to manage multiple tasks, with a constant awareness of coworkers and hazards. With high demands on visual and auditory resources, vibrotactile feedback systems offer a solution to enhance awareness without overburdening vision or hearing. (2) Aim: This study evaluates the impact of vibrotactile feedback regarding proximity to hazards on multitasking performance and cognitive workload in order to support hazard awareness in a controlled task environment. (3) Method: Twenty-four participants performed a joystick-controlled navigation task and a concurrent mental spatial rotation task. Proximity to hazards in the navigation task was conveyed via different encodings of vibrotactile feedback: No Vibration, Intensity-Modulation, Pulse Duration, and Pulse Spacing. Performance metrics, including obstacle collisions, target hits, contact time, and accuracy, were assessed alongside perceived workload. (4) Results: Intensity-Modulated feedback reduced obstacle collisions and proximity time, while lowering workload, compared to No Vibration. No significant effects were found on spatial rotation accuracy, indicating that vibrotactile feedback effectively guides navigation and supports spatial awareness. (5) Conclusions: This study highlights the potential of vibrotactile feedback to improve navigation performance and hazard awareness, offering valuable insights into multimodal safety systems in high-demand environments. 

Medical palpation is a task that traditionally requires a skilled practitioner to assess and diagnose a patient through direct touch and manipulation of their body. In regions with a shortage of such professionals, robotic hands or sensorized gloves could potentially capture the necessary haptic information during palpation exams and relay it to medical doctors for diagnosis. From an engineering perspective, a comprehensive understanding of the relevant motions and forces is essential for designing haptic technologies capable of fully capturing this information. This study focuses on thyroid examination palpation, aiming to analyze the hand motions and forces applied to the patient’s skin during the procedure. We identified key palpation techniques through video recordings and interviews and measured the force characteristics during palpation performed by both non-medical participants and medical professionals. Our findings revealed five primary palpation hand motions and characterized the multi-dimensional interaction forces involved in these motions. These insights provide critical design guidelines for developing haptic sensing and display technologies optimized for remote thyroid nodule palpation and diagnosis. 

Active, exploratory touch supports human perception of a broad set of invisible physical surface properties. When traditionally hands-on tasks, such as medical palpation of soft tissue, are translated to virtual settings, haptic perception is throttled by technological limitations, and much of the richness of active exploration can be lost. The current research seeks to restore some of this richness with advanced methods of passively conveying haptic data alongside synchronized visual feeds. A robotic platform presented haptic stimulation modeled after the relative motion between a hypothetical physician's hands and artificial tissue samples during palpation. Performance in discriminating the sizes of hidden “tumors” in these samples was compared across display conditions which included haptic feedback and either: 1) synchronized video of the participant's hand, recorded during active exploration; 2) synchronized video of another person's hand; 3) no accompanying video. The addition of visual feedback did not improve task performance, which was similar whether receiving relative motion recorded from one's own hand or someone else's. While future research should explore additional strategies to improve task performance, this initial attempt to translate active haptic sensations to passive presentations indicates that visuo-haptic feedback can induce reliable haptic perceptions of motion in a stationary passive hand.