Visual softness perception can be manipulated through exploratory procedures.

Both visual and haptic softness perception have recently been shown to have multiple dimensions, such as deformability, granularity, fluidity, surface softness, and roughness. During haptic exploration, people adjust their hand motions (exploratory procedures, EPs) based on the material qualities of the object and the particular information they intend to acquire. Some of these EPs are also shown to be associated with perceived softness dimensions, for example, stroking a silk blouse or applying pressure to a pillow. Here, we aimed to investigate whether we can manipulate observers' judgments about softness attributes through exposure to videos of others performing various EPs on everyday soft materials. In two experiments, participants watched two videos of the same material: one with a corresponding EP and the other without correspondence; then, they judged these materials based on 12 softness-related adjectives (semantic differentiation method). The results of the second experiment suggested that when the EP is congruent with the dimension from which the material is chosen, the ratings for the adjectives from the same dimension are higher than the incongruent EP. This study provides evidence that participants can assess material properties from optic and mechanical cues without needing haptic signals. Additionally, our findings indicate that manipulating the hand motion can selectively facilitate material-related judgments.

Autonomous Robotic Systems in Otolaryngology-Head and Neck Surgery.

Robotic surgery is a growing field with increasing applications to patient care. With the rising use of artificial intelligence (AI), a new frontier emerges, allowing semiautonomous robotics. This article reviews the origins of robotic surgery and subsequent trials of automaticity in all fields. It then describes specific nascent robotic and semiautonomous surgical prototypes within the field of otolaryngology. Finally, broader systemic considerations are posited regarding the implementation of AI-driven robotics in surgery.

Investigating Haptic Feedback in Vision-Deficient Millirobot Telemanipulation.

The evolution of magnetically actuated millirobots gives rise to unique teleoperation challenges due to their non-traditional kinematic and dynamic architectures, as well as their frequent use of suboptimal imaging modalities. Recent investigations into haptic interfaces for millirobots have shown promise but lack the clinically motivated task scenarios necessary to justify future development. In this work, we investigate the utility of haptic feedback on bilateral teleoperation of a magnetically actuated millirobot in visually deficient conditions. We conducted an N=23 user study in an aneurysm coiling inspired procedure, which required participants to navigate the robot through a maze in near total darkness to manipulate beads to a target under simulated fluoroscopy. We hypothesized that users will be better able to complete the telemanipulation task with haptic feedback while reducing excess forces on their surroundings compared to the no feedback conditions. Our results showed an over 40% improvement in participants' bead scoring, a nearly 10% reduction in mean force, and 13% reduction in maximum force with haptic feedback, as well as significant improvements in other metrics. Results highlight that benefits of haptic feedback are retained when haptic feedback is removed. These findings suggest that haptic feedback has the potential to significantly improve millirobot telemanipulation and control in traditionally vision deficient tasks.

Clinical Results of a Monofocal Aspheric Bitoric Intraocular Lens with Plate Haptics in Hyperopic Eyes.

Purpose: To assess the refractive and visual outcomes of hyperopic and astigmatic eyes implanted with a monofocal, aspheric, bitoric intraocular lens (IOL) with plate haptics following cataract surgery. Methods: The study evaluated 51 eyes implanted with the AT TORBI 709M IOL (Carl Zeiss Meditec AG, Jena, Germany) during a follow-up of 12-months. Refractive error, rotational stability, monocular uncorrected distance visual acuity (UDVA), monocular corrected distance visual acuity (CDVA), and contrast sensitivity were analyzed at 1-, 6-, and 12-months post-surgery. Results: At 12 months, the cumulative CDVA was 20/25 in 94.12% of eyes and 20/32 or better in 98.04%. The UDVA was the same as, or better than, the CDVA in 88.24% of eyes. The mean logMAR UDVA and CDVA values were 0.06 ± 0.11 and 0.00 ± 0.08, respectively. In addition, 92.16% of eyes were within ±0.50 D and 98.04% were within ±1.00 D of a spherical equivalent, and 86.27% of eyes had refractive astigmatism ≤0.50D and 100% were ≤1.00D. The mean spherical equivalent was 0.21 ± 0.31D and the mean refractive cylinder 0.34 ± 0.27D. The IOL rotation was 1.18 ± 1.35 degrees and all eyes had a rotation ≤5 degrees. The log contrast sensitivity functions were good and similar for all spatial frequencies during follow-up. Conclusion: Our results demonstrate that implantation of the AT TORBI 709M IOL in hyperopic and astigmatic eyes is effective and safe. The visual and refractive outcomes were good, showing excellent rotational stability.

Haptic based fundamentals of laparoscopic surgery simulation for training with objective assessments.

Force is crucial for learning psychomotor skills in laparoscopic tissue manipulation. Fundamental laparoscopic surgery (FLS), on the other hand, only measures time and position accuracy. FLS is a commonly used training program for basic laparoscopic training through part tasks. The FLS is employed in most of the laparoscopic training systems, including box trainers and virtual reality (VR) simulators. However, many laparoscopic VR simulators lack force feedback and measure tissue damage solely through visual feedback based on virtual collisions. Few VR simulators that provide force feedback have subjective force metrics. To provide an objective force assessment for haptic skills training in the VR simulators, we extend the FLS part tasks to haptic-based FLS (HFLS), focusing on controlled force exertion. We interface the simulated HFLS part tasks with a customized bi-manual haptic simulator that offers five degrees of freedom (DOF) for force feedback. The proposed tasks are evaluated through face and content validity among laparoscopic surgeons of varying experience levels. The results show that trainees perform better in HFLS tasks. The average Likert score observed for face and content validity is greater than 4.6 ± 0.3 and 4 ± 0.5 for all the part tasks, which indicates the acceptance of the simulator among subjects for its appearance and functionality. Face and content validations show the need to improve haptic realism, which is also observed in existing simulators. To enhance the accuracy of force rendering, we incorporated a laparoscopic tool force model into the simulation. We study the effectiveness of the model through a psychophysical study that measures just noticeable difference (JND) for the laparoscopic gripping task. The study reveals an insignificant decrease in gripping-force JND. A simple linear model could be sufficient for gripper force feedback, and a non-linear LapTool force model does not affect the force perception for the force range of 0.5-2.5 N. Further study is required to understand the usability of the force model in laparoscopic training at a higher force range. Additionally, the construct validity of HFLS will confirm the applicability of the developed simulator to train surgeons with different levels of experience.

Static and Dynamic Hand Gestures: A Review of Techniques of Virtual Reality Manipulation.

This review explores the historical and current significance of gestures as a universal form of communication with a focus on hand gestures in virtual reality applications. It highlights the evolution of gesture detection systems from the 1990s, which used computer algorithms to find patterns in static images, to the present day where advances in sensor technology, artificial intelligence, and computing power have enabled real-time gesture recognition. The paper emphasizes the role of hand gestures in virtual reality (VR), a field that creates immersive digital experiences through the Ma blending of 3D modeling, sound effects, and sensing technology. This review presents state-of-the-art hardware and software techniques used in hand gesture detection, primarily for VR applications. It discusses the challenges in hand gesture detection, classifies gestures as static and dynamic, and grades their detection difficulty. This paper also reviews the haptic devices used in VR and their advantages and challenges. It provides an overview of the process used in hand gesture acquisition, from inputs and pre-processing to pose detection, for both static and dynamic gestures.

A usability analysis of augmented reality and haptics for surgical planning.

PURPOSE: Proper visualization and interaction with complex anatomical data can improve understanding, allowing for more intuitive surgical planning. The goal of our work was to study what the most intuitive yet practical platforms for interacting with 3D medical data are in the context of surgical planning. METHODS: We compared planning using a monitor and mouse, a monitor with a haptic device, and an augmented reality (AR) head-mounted display which uses a gesture-based interaction. To determine the most intuitive system, two user studies, one with novices and one with experts, were conducted. The studies involved planning of three scenarios: (1) heart valve repair, (2) hip tumor resection, and (3) pedicle screw placement. Task completion time, NASA Task Load Index and system-specific questionnaires were used for the evaluation. RESULTS: Both novices and experts preferred the AR system for pedicle screw placement. Novices preferred the haptic system for hip tumor planning, while experts preferred the mouse and keyboard. In the case of heart valve planning, novices preferred the AR system but there was no clear preference for experts. Both groups reported that AR provides the best spatial depth perception. CONCLUSION: The results of the user studies suggest that different surgical cases may benefit from varying interaction and visualization methods. For example, for planning surgeries with implants and instrumentations, mixed reality could provide better 3D spatial perception, whereas using landmarks for delineating specific targets may be more effective using a traditional 2D interface.

A Wearable Fingertip Force Feedback Device System for Object Stiffness Sensing.

Virtual reality technology brings a new experience to human-computer interaction, while wearable force feedback devices can enhance the immersion of users in interaction. This paper proposes a wearable fingertip force feedback device that uses a tendon drive mechanism, with the aim of simulating the stiffness characteristics of objects within virtual scenes. The device adjusts the rotation angle of the torsion spring through a DC motor, and then uses a wire to convert the torque into a feedback force at the user's index fingertips, with an output force of up to 4 N and a force change rate of up to 10 N/s. This paper introduces the mechanical structure and design process of the force feedback device, and conducts a mechanical analysis of the device to select the appropriate components. Physical and psychological experiments are conducted to comprehensively evaluate the device's performance in conveying object stiffness information. The results show that the device can simulate different stiffness characteristics of objects, and users can distinguish objects with different stiffness characteristics well when wearing the force feedback device and interacting with the three-dimensional virtual environments.

A haptic guidance system for simulated catheter navigation with different kinaesthetic feedback profiles.

BACKGROUND: This paper proposes a haptic guidance system to improve catheter navigation within a simulated environment. METHODS: Three force profiles were constructed to evaluate the system: collision prevention; centreline navigation; and a novel force profile of reinforcement learning (RL). All force profiles were evaluated from the left common iliac to the right atrium. RESULTS: Our findings show that providing haptic feedback improved surgical safety compared to visual-only feedback. If staying inside the vasculature is the priority, RL provides the safest option. It is also shown that the performance of each force profile varies in different anatomical regions. CONCLUSION: The implications of these findings are significant, as they hold the potential to improve how and when haptic feedback is applied for cardiovascular intervention.

Enhancing robotic telesurgery with sensorless haptic feedback.

PURPOSE: This paper evaluates user performance in telesurgical tasks with the da Vinci Research Kit (dVRK), comparing unilateral teleoperation, bilateral teleoperation with force sensors and sensorless force estimation. METHODS: A four-channel teleoperation system with disturbance observers and sensorless force estimation with learning-based dynamic compensation was developed. Palpation experiments were conducted with 12 users who tried to locate tumors hidden in tissue phantoms with their fingers or through handheld or teleoperated laparoscopic instruments with visual, force sensor, or sensorless force estimation feedback. In a peg transfer experiment with 10 users, the contribution of sensorless haptic feedback with/without learning-based dynamic compensation was assessed using NASA TLX surveys, measured free motion speeds and forces, environment interaction forces as well as experiment completion times. RESULTS: The first study showed a 30% increase in accuracy in detecting tumors with sensorless haptic feedback over visual feedback with only a 5-10% drop in accuracy when compared with sensor feedback or direct instrument contact. The second study showed that sensorless feedback can help reduce interaction forces due to incidental contacts by about 3 times compared with unilateral teleoperation. The cost is an increase in free motion forces and physical effort. We show that it is possible to improve this with dynamic compensation. CONCLUSION: We demonstrate the benefits of sensorless haptic feedback in teleoperated surgery systems, especially with dynamic compensation, and that it can improve surgical performance without hardware modifications.

Haptics in fixed prosthodontics and their role in dental education: A literature review.

Technological progress leads to new advances in dental education. One of the applications involves the use of virtual and augmented reality as educational aids. The emerging question is to establish if and how these enhancements may prove beneficial to the overall student learning process. A review of recent literature was conducted with the aim of providing evidence for the development of relevant clinical guidelines. The proposed topic attempted to provide answers to the questions of (a) how participants perform when using haptic devices compared to traditional tooth preparation methods on typodonts, (b) how the use of simulators is perceived by both students and educators, and (c) what added value simulators may have in prosthetic dentistry training. The main findings of this study showed that participants expressed satisfaction with the educational experience, finding it both stimulating and very similar to the actual clinical environment. However, differences between haptic and conventional methods were also apparent. Haptics was a significant predictor of clinical crown performance. Significantly better results and shorter preparation times tended to increase with experience. In conclusion, self-directed learning appears to be beneficial in the clinical education that follows data-driven approach. At the pre-laboratory level, simulators may act as an initial familiarization instrument. At the preclinical level, they may aid in detecting students who require extra assistance, or to provide extra training hours for students lacking adequate competency to enter the clinical training phase.

SORI: A softness-rendering interface to unravel the nature of softness perception.

Tactile perception of softness serves a critical role in the survival, well-being, and social interaction among various species, including humans. This perception informs activities from food selection in animals to medical palpation for disease detection in humans. Despite its fundamental importance, a comprehensive understanding of how softness is neurologically and cognitively processed remains elusive. Previous research has demonstrated that the somatosensory system leverages both cutaneous and kinesthetic cues for the sensation of softness. Factors such as contact area, depth, and force play a particularly critical role in sensations experienced at the fingertips. Yet, existing haptic technologies designed to explore this phenomenon are limited, as they often couple force and contact area, failing to provide a real-world experience of softness perception. Our research introduces the softness-rendering interface (SORI), a haptic softness display designed to bridge this knowledge gap. Unlike its predecessors, SORI has the unique ability to decouple contact area and force, thereby allowing for a quantitative representation of softness sensations at the fingertips. Furthermore, SORI incorporates individual physical fingertip properties and model-based softness cue estimation and mapping to provide a highly personalized experience. Utilizing this method, SORI quantitatively replicates the sensation of softness on stationary, dynamic, homogeneous, and heterogeneous surfaces. We demonstrate that SORI accurately renders the surfaces of both virtual and daily objects, thereby presenting opportunities across a range of fields, from teleoperation to medical technology. Finally, our proposed method and SORI will expedite psychological and neuroscience research to unlock the nature of softness perception.

Child development and the role of visual experience in the use of spatial and non-spatial features in haptic object perception.

Previous work has suggested a different developmental timeline and role of visual experience for the use of spatial and non-spatial features in haptic object recognition. To investigate this conjecture, we used a haptic ambiguous odd-one-out task in which one object needed to be selected as being different from two other objects. The odd-one-out could be selected based on four characteristics: size, shape (spatial), texture, and weight (non-spatial). We tested sighted children from 4 to 12 years of age; congenitally blind, late blind, and adult participants with low vision; and normally sighted adults. Given the protracted developmental time course for spatial perception, we expected a shift from a preference for non-spatial features toward spatial features during typical development. Due to the dominant influence of vision for spatial perception, we expected congenitally blind adults to show a similar preference for non-spatial features as the youngest children. The results confirmed our first hypothesis; the 4-year-olds demonstrated a lower dominance for spatial features for object classification compared with older children and sighted adults. In contrast, our second hypothesis was not confirmed; congenitally blind adults' preferred categorization criteria were indistinguishable from those of sighted controls. These findings suggest an early development, but late maturation, of spatial processing in haptic object recognition independent of visual experience.

Haptics Vs Typodonts for Crown Preparation in Undergraduate Dental Student Education.

OBJECTIVES: This study aims to compare students' subjective perceptions and objective results by comparing two methods of crown preparation: typodonts and haptics. MATERIALS AND METHODS: Fifty-four second-year students were given instructions on crown preparation for the upper right second premolar. First on typodonts and then with haptics. They were given five minutes to familiarize with the artificial environment and then thirty minutes for the actual preparation. Finally, they completed a questionnaire about their experience. Their preparations were objectively compared by measuring the angle of total occlusal convergence-TOC on the typodonts and with haptics. RESULTS: Students reported that haptics can enhance the learning process and that they would use them for skill training in the future. Overall, their experience was rated as positive. The TOC of teeth prepared with haptics was significantly higher than those prepared with typodonts, but all values were within the acceptable range. CONCLUSION: Although students did not prefer haptics to typodonts, haptics appear to be a powerful tool in the educational process because it can be a complementary option to traditional methods at the preclinical level.

Developmental changes in the visual, haptic, and bimodal perception of geometric angles.

Geometrical knowledge is typically taught to children through a combination of vision and repetitive drawing (i.e. haptics), yet our understanding of how different spatial senses contribute to geometric perception during childhood is poor. Studies of line orientation suggest a dominant role of vision affecting the calibration of haptics during development; however, the associated multisensory interactions underpinning angle perception are unknown. Here we examined visual, haptic, and bimodal perception of angles across three age groups of children: 6 to 8 years, 8 to 10 years, and 10 to 12 years, with age categories also representing their class (grade) in primary school. All participants first learned an angular shape, presented dynamically, in one of three sensory tracing conditions: visual only, haptic only, or bimodal exploration. At test, which was visual only, participants selected a target angle from four possible alternatives with distractor angle sizes varying relative to the target angle size. We found a clear improvement in accuracy of angle perception with development for all learning modalities. Angle perception in the youngest group was equally poor (but above chance) for all modalities; however, for the two older child groups, visual learning was better than haptics. Haptic perception did not improve to the level of vision with age (even in a comparison adult group), and we found no specific benefit for bimodal learning over visual learning in any age group, including adults. Our results support a developmental increment in both spatial accuracy and precision in all modalities, which was greater in vision than in haptics, and are consistent with previous accounts of cross-sensory calibration in the perception of geometric forms.

Measuring tactile sensitivity and mixed-reality-assisted exercise for carpal tunnel syndrome by ultrasound mid-air haptics.

Introduction: Carpal tunnel syndrome (CTS) is the most common nerve entrapment neuropathy, which causes numbness and pain in the thumb, the index and middle fingers and the radial side of the ring finger. Regular hand exercises may improve the symptoms and prevent carpal tunnel surgery. This study applied a novel ultrasonic stimulation method to test tactile sensitivity in CTS and also a mixed-reality-assisted (MR-assisted) exercise program which measured hand movements and provided haptic feedback for rehabilitation. Methods: Twenty patients with mild unilateral CTS took part in the experiments. A mid-air haptics device (Ultrahaptics STRATOS Explore) was used to apply amplitude-modulated ultrasound waves (carrier frequency: 40 kHz) onto the skin to create tactile stimulation mechanically. Participants performed a two-alternative forced-choice task for measuring tactile thresholds at 250-Hz modulation frequency. They were tested at the index fingers and the thenar eminences of both hands. Additionally, 15 CTS patients used an MR-assisted program to do hand exercises with haptic feedback. Exercise performance was assessed by calculating errors between target and actual hand configurations. System Usability Scale (SUS) was adopted to verify the practical usability of the program. Results: Thresholds at the thenar eminences of the affected and healthy hands were not significantly different. While the thresholds at the healthy index fingers could be measured, those of the affected fingers were all higher than the stimulation level produced by the maximum output from the ultrasound device. In the exercise program, a significant positive correlation (ρ = 0.89, p < 0.001) was found between the performance scores and the SUS scores, which were above the criterion value established in the literature. Discussion: The results show that thenar tactile sensitivity is not affected in mild CTS as expected from the palmar cutaneous branch of the median nerve (PCBm), but index finger threshold is likely to be higher. Overall, this study suggests that mid-air haptics, with certain improvements, may be used as a preliminary test in the clinical setting. Moreover, the device is promising to develop gamified rehabilitation programs and for the treatment follow-up of CTS.

User confidence and electrodermal activity during haptic exploration for perceptual comparisons using a robotic system.

Children with physical impairments may have trouble effectively performing the hand movements used in haptic exploration and may miss information about object properties. Assistive robotic systems with haptic feedback may enable children with physical impairments to haptically explore objects. However, it is important to understand if they might be encountering difficulty in assessing object properties with the system. As such, we examined two methods to ascertain a user's uncertainty or stress when doing the exploration, user confidence and electrodermal activity (EDA). Twenty adults and ten children without physical impairments manipulated four pairs of objects to examine size, roughness, hardness and shape. All participants performed the manipulation by controlling a robotic system and by manual exploration in a randomized crossover design. Adults' confidence was lower when using the robotic system and correlated with lower accuracy at determining object properties. Children's responses indicated that they may not have understood how to self-rate confidence. EDA, a potentially objective measure of stress during the task, was actually lower for adults when they used the robotic system, suggesting less physiological arousal than when using their hands. Children's EDA was variable.

Telehealth and Virtual Reality Technologies in Chronic Pain Management: A Narrative Review.

PURPOSE OF REVIEW: This review provides medical practitioners with an overview of the present and emergent roles of telehealth and associated virtual reality (VR) applications in chronic pain (CP) management, particularly in the post-COVID-19 healthcare landscape. RECENT FINDINGS: Accumulated evidence points to the efficacy of now well-established telehealth modalities, such as videoconferencing, short messaging service (SMS), and mobile health (mHealth) applications in complementing remote CP care. More recently, and although still in early phases of clinical implementation, a wide range of VR-based interventions have demonstrated potential for improving the asynchronous remote management of CP. Additionally, VR-associated technologies at the leading edge of science and engineering, such as VR-assisted biofeedback, haptic technology, high-definition three-dimensional (HD3D) conferencing, VR-enabled interactions in a Metaverse, and the use of wearable monitoring devices, herald a new era for remote, synchronous patient-physician interactions. These advancements hold the potential to facilitate remote physical examinations, personalized remote care, and innovative interventions such as ultra-realistic biofeedback. Despite the promise of VR-associated technologies, several limitations remain, including the paucity of robust long-term effectiveness data, heterogeneity of reported pain-related outcomes, challenges with scalability and insurance coverage, and demographic-specific barriers to patient acceptability. Future research efforts should be directed toward mitigating these limitations to facilitate the integration of telehealth-associated VR into the conventional management of CP. Despite ongoing barriers to widespread adoption, recent evidence suggests that VR-based interventions hold an increasing potential to complement and enhance the remote delivery of CP care.

The Single-Pitch Texel: A flexible and practical texture-rendering algorithm.

As the number of applications for tactile feedback technology rapidly increases, so too does the need for efficient, flexible, and extensible representations of virtual textures. The previously introduced Single-Pitch Texel rendering algorithm offers designers the ability to produce textures with perceptually wide-band spectral characteristics while requiring very few input parameters. This paper expands on the capabilities of the rendering algorithm. Diverse families of fine textures, with widely varied spectral characteristics, were shown to be rendered reliably using the Texel algorithm. Furthermore, by leveraging an assistive algorithm, subjects were shown to consistently navigate the Texel parameter space in a matching task. Finally, a psychophysical study was conducted to demonstrate the rendering algorithm's resilience to spectral quantization, further reducing the data required to represent a virtual texture.

Accuracy and Precision of Haptic Robotic-Guided Implant Surgery in a Large Consecutive Series.

PURPOSE: To determine the accuracy of dental implant placement using haptic robotic guidance in a large clinical series. MATERIALS AND METHODS: In a prospective single-arm clinical study, 108 patients received 273 individual endosteal implants. A virtual preoperative restorative and surgical plan was created from a CBCT scan and matched to the surgical workspace on the day of surgery via either a tooth-based or bone-based fiducial splint. Intraoperatively, the surgeon manipulated a handpiece attached to a haptic robotic guidance arm. A variety of drills and implants were used. Both the osteotomy and the implant placement were guided by 3D haptic constraints according to the virtual plan. Postoperative CBCT scans permitted the calculation of the actual implant placement deviations compared to the plan for accuracy. Precision was calculated by comparing SDs from published literature. RESULTS: The implants were evenly distributed by arch, with 47% placed in the maxilla and 53% in the mandible. The mean ± SD signed depth deviation was 0.14 ± 0.87 mm proud. The global angular deviation averaged 1.42 ± 1.53 degrees, with 95% confidence limits of 1.24 and 1.60 degrees. The crown of the actual placed implant showed an average deviation from the plan of 1.10 ± 0.69 mm and the apex of the placed implant showed a deviation of 1.12 ± 0.69 mm. Haptic robotic guidance showed greater precision than freehand, static computerguided, and dynamic computer-guided implant placement. CONCLUSIONS: This large clinical series of 273 implants shows a high accuracy of implant placement compared to the published accuracy for angular deviations for any technology, as well as demonstrating statistically greater precision. Long-term clinical studies are necessary to establish the true effect of increased accuracy on clinical outcomes. Using haptic robotic guidance provides accurate implant placement while allowing additional benefits compared to computer-guided surgery, namely full visualization of the surgical field and the ability to change the plan intraoperatively.