Search

Real-world application of haptic feedback from kinesthetic devices is implemented while the user is in motion, but human wrist torque magnitude discrimination has previously only been characterized while users are stationary. In this study, we measured wrist torque discrimination in conditions relevant to activities of daily living, using a previously developed backdrivable wrist exoskeleton capable of applying wrist flexion and extension torque. We implemented a torque comparison test using a two-alternative forced-choice paradigm while participants were both seated and walking on a treadmill, with both a stationary and a moving wrist. Like most kinesthetic haptic devices, the wrist exoskeleton output torque is commanded in an open-loop manner. Thus, the study design was informed by Monte Carlo simulations to verify that the errors in the wrist exoskeleton output torque would not significantly affect the results. Results from ten participants show that although both walking and moving wrist conditions result in higher Weber Fractions (worse perception), participants were able to detect relatively small changes in torque of 12-19% on average in all grouped conditions. The results provide insight regarding the torque magnitudes necessary to make wrist-worn kinesthetic haptic devices noticeable and meaningful to the user in various conditions relevant to activities of daily living.

Continuum and soft robots can leverage complex actuator shapes to take on useful shapes while actuating only a few of their many degrees of freedom. Continuum robots that also grow increase the range of potential shapes that can be actuated and enable easier access to constrained environments. Existing models for describing the complex kinematics involved in general actuation of continuum robots rely on simulation or well-behaved stress-strain relationships, but the non-linear behavior of the thin-walled inflated-beams used in growing robots makes these techniques difficult to apply. Here we derive kinematic models of single, generally routed tendon paths on a soft pneumatic backbone of inextensible but flexible material from geometric relationships alone. This allows for forward modeling of the resulting shapes with only knowledge of the geometry of the system. We show that this model can accurately predict the shape of the whole robot body and how the model changes with actuation type. We also demonstrate the use of this kinematic model for inverse design, where actuator designs are found based on desired final robot shapes. We deploy these designed actuators on soft pneumatic growing robots to show the benefits of simultaneous growth and shape change., 21 pages, 18 figures

There is increasing interest in the African spiny mouse (Acomys cahirinus) as a model organism because of its ability for regeneration of tissue after injury in skin, muscle, and internal organs such as the kidneys. A high-quality reference genome is needed to better understand these regenerative properties at the molecular level. Here, we present an improved reference genome forA. cahirinusgenerated from long Nanopore sequencing reads. We confirm the quality of our annotations using RNA sequencing data from four different tissues. Our genome is of higher contiguity and quality than previously reported genomes from this species and will facilitate ongoing efforts to better understand the regenerative properties of this organism.

During social interactions, people use auditory, visual, and haptic cues to convey their thoughts, emotions, and intentions. Due to weight, energy, and other hardware constraints, it is difficult to create devices that completely capture the complexity of human touch. Here we explore whether a sparse representation of human touch is sufficient to convey social touch signals. To test this we collected a dataset of social touch interactions using a soft wearable pressure sensor array, developed an algorithm to map recorded data to an array of actuators, then applied our algorithm to create signals that drive an array of normal indentation actuators placed on the arm. Using this wearable, low-resolution, low-force device, we find that users are able to distinguish the intended social meaning, and compare performance to results based on direct human touch. As online communication becomes more prevalent, such systems to convey haptic signals could allow for improved distant socializing and empathetic remote human-human interaction., Comment: Copyright 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works

The revised 2018 ISN/RPS Classification System for lupus nephritis (LN) includes calculations for both activity index (A.I.) and chronicity index (C.I.). Unchanged were the thresholds of 25%, 25-50%, and 50% crescents to distinguish between mild, moderate, and severe activity/chronicity. We aimed to evaluate these thresholds for percent crescents in childhood-onset LN.Eighty-six subjects 21 years of age were enrolled from the Pediatric Glomerulonephritis with Crescents Registry, a retrospective multi-center cohort sponsored by the Pediatric Nephrology Research Consortium. Thresholds of 10%, 25%, and 50% for both cellular/fibrocellular and fibrous crescents were interrogated for primary outcomes of kidney failure, eGFR, and eGFR slope.Median age at time of initial biopsy was 14 years (range 1-21). Median follow-up time was 3 years (range 1-11). Cumulative incidence of kidney failure was 6% at 1 year and 10% at latest follow-up. Median eGFR slope was - 18 mL/1.73 mIn children with crescentic LN, use of 10% and 25% thresholds for cellular crescents better reflects disease activity, while these thresholds for fibrous crescents better discriminates kidney disease outcomes. A higher resolution version of the Graphical abstract is available as Supplementary information.

Online learning is an important aspect of higher education today. One-third of college students take at least one course online, and almost 70% of chief academic leaders say that online learning is critical to their long-term strategy [1]. Despite the success and growth of online education, the number of courses that currently offer a hands-on laboratory component is extremely limited, resulting in the lack of an entire category of engineering courses.

Lupus nephritis (LN) is a life-threatening manifestation of systemic lupus erythematosus (SLE) and is more common in children than adults. The epidemiology and management of childhood-onset SLE (cSLE) have changed over time, prompting the need to reassess expected outcomes. The purpose of this study is to use the Childhood Arthritis and Rheumatology Research Alliance (CARRA) prospective registry to validate historical principles of LN in a contemporary, real-world cohort. After an extensive literature review, six principles of LN in cSLE were identified. The CARRA registry was queried to evaluate these principles in determining the rate of LN in cSLE, median time from cSLE diagnosis to LN, short-term renal outcomes, and frequency of rituximab as an induction therapy. Of the 677 cSLE patients in the CARRA registry, 32% had documented LN. Decline in kidney function was more common in Black cSLE patients than non-Black patients ( p = 0.04). Black race was associated with worse short-term renal outcomes. In short-term follow up, most children with LN had unchanged or improved kidney function, and end stage kidney disease (ESKD) was rare. Ongoing follow-up of cSLE patients in the CARRA registry will be necessary to evaluate long-term outcomes to inform risk, management, and prognosis of LN in cSLE.

ObjectiveWe aimed to develop a system for people with amputation that non-invasively restores missing control and sensory information for an ankle-foot prosthesis.MethodsIn our approach, a wrist exoskeleton allows people with amputation to control and receive feedback from their prosthetic ankle via teleoperation. We implemented two control schemes: position control with haptic feedback of ankle torque at the wrist; and torque control that allows the user to modify a baseline torque profile by moving their wrist against a virtual spring. We measured tracking error and frequency response for the ankle-foot prosthesis and the wrist exoskeleton. To demonstrate feasibility and evaluate system performance, we conducted an experiment in which one participant with a transtibial amputation tracked desired wrist trajectories during walking, while we measured wrist and ankle response.ResultsBenchtop testing demonstrated that for relevant walking frequencies, system error was below human perceptual error. During the walking experiment, the participant was able to voluntarily follow different wrist trajectories with an average RMS error of 1.55° after training. The ankle was also able to track desired trajectories below human perceptual error for both position control (RMSE = 0.8°) and torque control (RMSE = 8.4%).ConclusionWe present a system that allows a user with amputation to control an ankle-foot prosthesis and receive feedback about its state using a wrist exoskeleton, with accuracy comparable to biological neuromotor control.SignificanceThis bilateral teleoperation system enables novel prosthesis control and feedback strategies that could improve prosthesis control and aid motor learning.

Vibratory stimulation may improve post-stroke symptoms such as spasticity; however, current studies are limited by the large, clinic-based apparatus used to apply this stimulation. A wearable device could provide vibratory stimulation in a mobile form, enabling further study of this technique. An initial device, the vibrotactile stimulation (VTS) Glove, was deployed in an eight-week clinical study in which sixteen individuals with stroke used the device for several hours daily. Participants reported wearing the glove during activities such as church, social events, and dining out. However, 69% of participants struggled to extend or insert their fingers to don the device. In a follow-up study, eight individuals with stroke evaluated new VTS device prototypes in a three-round iterative design study with the aims of creating the next generation of VTS devices and understanding features that influence interaction with a wearable device by individuals with impaired upper-limb function. Interviews and interaction tasks were used to define actionable design revisions between each round of evaluation. Our analysis identified six new themes from participants regarding device designs: hand supination is challenging, separate finger attachments inhibit fit and use, fingers may be flexed or open, fabric coverage impacts comfort, a reduced concern for social comfort, and the affected hand is infrequently used. Straps that wrap around the arm and fixtures on the anterior arm were other challenging features. We discuss potential accommodations for these challenges, as well as social comfort. New VTS device designs are presented and were donned in an average time of 48 seconds.

Fibrosis-driven solid organ failure is a major global health burden. Spiny mice (genus: Acomys ) are terrestrial mammals that regenerate severe skin wounds without scars to avoid predation. To test whether spiny mice can also regenerate internal organ injuries, we performed acute obstructive or ischemic surgeries on adult kidneys of Acomys cahirinus compared to Mus musculus. Despite equivalent acute tissue damage, Acomys fully regenerate nephron structure, vascular & lymphatic networks, and organ function without fibrosis by 14d while Mus (CD1 or C57BL/6) develop extensive interstitial fibrosis and progress to organ failure and death. Comparative transcriptomic, epigenetic, and single-cell assays revealed that the Acomys genome appears poised to initiate a regenerative response at the time of injury. In addition, we found the Hippo pathway effector protein YAP localized to the nucleus in renal tubular epithelial cells (RTEs) undergoing scarless wound healing in Acomys while it was either cytoplasmic or not detectable in Mus RTEs. Experiments in vitro revealed an accelerated PP2A-dependent YAP phosphatase activity that maintained nuclear YAP in Acomys RTEs and was not detected in Mus or human cells. Treatment of Acomys in vivo with the nuclear YAP-TEAD inhibitor verteporfin converted tissue regeneration to fibrosis in the dermis and similar experiments for the kidney are in progress. These results suggest that the spiny mouse genome evolved both transcriptional and post-translational adaptations important for scar-free regenerative wound healing in vivo .

The winds of Patagonia are referred to by locals as "The Broom of God" because they sweep away the less fit species that cannot survive there. Fitness as an evolutionary trait has been considered as fundamental for many aspects of morphogenesis and behavior in metazoans. Yet, it has not received much attention in the area of wound healing, despite the obvious relevance of this polygenic trait to an organism's survival in nature. In this chapter, we review the evidence that the rodent species Acomys cahirinus is an emerging mammalian model system that has evolved a non-typical (for mammals) wound healing response that offers unique opportunities for the study of organ regeneration without fibrosis in an adult mammalian species.

Fibrosis-driven solid organ failure is a major world-wide health burden with few therapeutic options. Spiny mice (genus: Acomys) are terrestrial mammals that regenerate severe skin wounds without fibrotic scars to evade predators. Recent studies have shown that spiny mice also regenerate acute ischemic and traumatic injuries to kidney, heart, spinal cord, and skeletal muscle. A common feature of this evolved wound healing response is a lack of formation of fibrotic scar tissue that degrades organ function, inhibits regeneration, and leads to organ failure. Complex tissue regeneration is an extremely rare property among mammalian species. In this article, we discuss the evidence that Acomys represents an emerging model organism that offers a unique opportunity for the biomedical community to investigate and clinically translate molecular mechanisms of scarless wound healing and regeneration of organ function in a mammalian species.

Haptic guidance can be beneficial for aiding or training human users in many applications, such as teleoperation, rehabilitation, and navigation. Existing world-grounded haptic devices can provide effective multi-degree-of-freedom movement guidance. Wearable or holdable haptic devices can enable larger workspaces and unencumbered movement, but their use in guidance beyond one or two degrees of freedom has been limited. A holdable haptic device, called the Pantogripper, was previously presented in a study demonstrating its intuitive, directional guidance cues in four separate degrees of freedom. Here, using the same device, we present a controller for providing continuous closed-loop guidance for path following. In a human study, participants followed translation and rotation guidance from the device to successfully traverse three 3D paths with either no visual feedback or only a visual preview of the paths. Results indicate promise for holdable haptic devices to effectively provide high-degree-of-freedom movement guidance when visual guidance is unavailable or unsuitable.

A new class of continuum robots has recently been explored, characterized by tip extension, significant length change, and directional control. Here, we call this class of robots "vine robots," due to their similar behavior to plants with the growth habit of trailing. Due to their growth-based movement, vine robots are well suited for navigation and exploration in cluttered environments, but until now, they have not been deployed outside the lab. Portability of these robots and steerability at length scales relevant for navigation are key to field applications. In addition, intuitive human-in-the-loop teleoperation enables movement in unknown and dynamic environments. We present a vine robot system that is teleoperated using a custom designed flexible joystick and camera system, long enough for use in navigation tasks, and portable for use in the field. We report on deployment of this system in two scenarios: a soft robot navigation competition and exploration of an archaeological site. The competition course required movement over uneven terrain, past unstable obstacles, and through a small aperture. The archaeological site required movement over rocks and through horizontal and vertical turns. The robot tip successfully moved past the obstacles and through the tunnels, demonstrating the capability of vine robots to achieve navigation and exploration tasks in the field.

In this paper, we present a planning framework that uses a combination of implicit (robot motion) and explicit (visual/audio/haptic feedback) communication during mobile robot navigation. First, we developed a model that approximates both continuous movements and discrete behavior modes in human navigation, considering the effects of implicit and explicit communication on human decision making. The model approximates the human as an optimal agent, with a reward function obtained through inverse reinforcement learning. Second, a planner uses this model to generate communicative actions that maximize the robot's transparency and efficiency. We implemented the planner on a mobile robot, using a wearable haptic device for explicit communication. In a user study of an indoor human-robot pair of orthogonal crossing situation, the robot was able to actively communicate its intent to users in order to avoid collisions and facilitate efficient trajectories. Results showed that the planner generated plans that were easier to understand, reduced users' effort, and increased users' trust of the robot, compared to simply performing collision avoidance. The key contribution of this work is the integration and analysis of explicit communication (together with implicit communication) for social navigation.

Haptic shape displays provide compelling touch interactions by allowing users to freely explore a rendered surface. However, these displays are currently limited to 2.5-D surfaces due to the space requirements of their actuation. Building on previous work in haptic jamming, we developed a novel, soft 3-D shape display. A fully 3-D display that a user can grasp and hold allows for improved interactions for applications such as medical palpation training and virtual reality experiences. The shape display is implemented as an inflatable silicone membrane with embedded particle jamming cells that change stiffness and soft pneumatic actuators that control the distance between points on the surface. The device was modeled as a mass-spring system, and this model is used to develop a control sequence for a device to match a target shape. Due to constraints in actuation imposed by the 3-D geometry of the device, we developed an automatic design algorithm for the display, so that a display can be custom-designed to reach a set of target shapes using a relatively small number of actuators.

We present the design, evolution and analysis of "Hapkit," a low-cost, open-source kinesthetic haptic device for use in educational applications. Hapkit was developed in 2013 based on the design of the Stanford Haptic Paddle, with the goal of decreasing cost and increasing accessibility for educational applications, including online teaching, K-12 school use, and college dynamic systems and control courses. In order to develop Hapkit for these purposes, we tested a variety of transmission, actuation, and structural materials. Hapkit 3.0, the latest version, uses a capstan drive, inexpensive DC motor, and 3-D printed structural materials. A frequency-domain system identification method was used to characterize Hapkit dynamics across the various designs. This method was validated using a first principles parameter measurement and a transient response analysis. This characterization shows that Hapkit 3.0 has lower damping and Coulomb friction than previous designs. We also performed a user study demonstrating that Hapkit 3.0 improves discrimination of virtual stiffness compared to previous designs. The design evolution of Hapkit resulted in a low-cost, high-performance device appropriate for open-source dissemination and educational applications.

Tip-extending soft robots that "grow" via pneumatic eversion of their body material have demonstrated applications in exploration of cluttered environments. During growth, the motion and force of the robot tip can be controlled in three degrees of freedom using actuators that direct the tip in combination with extension. However, when reversal of the growth process is attempted by retracting the internal body material from the base, the robot body often responds by buckling rather than inverting the body material, making control of tip motion and force impossible. We present and validate a model to predict when buckling occurs instead of inversion, and we present an electromechanical device that can be added to a tip-extending soft robot to prevent buckling during retraction, restoring the ability of steering actuators to control the robot's motion and force during inversion. Using our retraction device, we demonstrate three previously impossible tasks: exploring different branches of a forking path, reversing growth while applying minimal force on the environment, and bringing back environment samples to the base., Comment: Under review for the IEEE Robotics and Automation Letters. Video available at https://www.youtube.com/watch?v=Vw8cArH0vxk

The properties of radio frequency electromagnetic systems can be manipulated by changing the 3D geometry of the system. Most reconfiguration schemes specify different conductive pathways using electrical switches in mechanically static systems, or they actuate and reshape a continuous metallic structure. Here, we demonstrate a novel strategy that utilizes soft continuum robots to both dynamically assemble electrical pathways and mechanically reconfigure 3D electromagnetic devices. Our concept consists of using soft robotic actuation to conductively connect multiple subwavelength-scale metallic building blocks, which form into electromagnetic structures when joined together. Soft robots offer an exciting avenue for electromagnetic device construction because they can form complex, high curvature shapes from low-loss dielectric materials using straightforward manufacturing methods. As a proof of concept, we experimentally implement a helical antenna that can switch chirality through tendon actuation of a soft pneumatic continuum robot. Our work introduces a new paradigm for electromagnetic reconfiguration using soft robotic platforms.

Navigation and motion control of a robot to a destination are tasks that have historically been performed with the assumption that contact with the environment is harmful. This makes sense for rigid-bodied robots where obstacle collisions are fundamentally dangerous. However, because many soft robots have bodies that are low-inertia and compliant, obstacle contact is inherently safe. As a result, constraining paths of the robot to not interact with the environment is not necessary and may be limiting. In this paper, we mathematically formalize interactions of a soft growing robot with a planar environment in an empirical kinematic model. Using this interaction model, we develop a method to plan paths for the robot to a destination. Rather than avoiding contact with the environment, the planner exploits obstacle contact when beneficial for navigation. We find that a planner that takes into account and capitalizes on environmental contact produces paths that are more robust to uncertainty than a planner that avoids all obstacle contact., Comment: 15 pages, 18 figures, supplementary video included and higher resolution available at https://youtu.be/XdTdFLz2TWU

The complex immunosuppressive nature of solid tumor microenvironments poses a significant challenge to generating efficacious and durable anticancer responses. Photoimmunotherapy is a cancer treatment strategy by which an antibody is conjugated with a non-toxic light-activatable dye. Following administration of the conjugate and binding to the target tumor, subsequent local laser illumination activates the dye, resulting in highly specific target cell membrane disruption. Here we demonstrate that photoimmunotherapy treatment elicited tumor necrosis, thus inducing immunogenic cell death characterized by the release of damage-associated molecular patterns (DAMPs). Photoimmunotherapy-killed tumor cells activated dendritic cells (DC), leading to the production of proinflammatory cytokines, T cell stimulation, priming antigen-specific T cells, and durable memory T cell responses, which led complete responder mice to effectively reject new tumors upon rechallenge. PD-1 blockade in combination with photoimmunotherapy enhanced overall anticancer efficacy, including against anti-PD-1-resistant tumors. The combination treatment also elicited abscopal anticancer activity, as observed by reduction of distal, non-illuminated tumors, further demonstrating the ability of photoimmunotherapy to harness local and peripheral T cell responses. With this work we therefore delineate the immune mechanisms of action for photoimmunotherapy and demonstrate the potential for cancer-targeted photoimmunotherapy to be combined with other immunotherapy approaches for augmented, durable anticancer efficacy. Moreover, we demonstrate responses utilizing various immunocompetent mouse models, as well as in vitro data from human cells, suggesting broad translational potential.

When humans socially interact with another agent (e.g., human, pet, or robot) through touch, they do so by applying varying amounts of force with different directions, locations, contact areas, and durations. While previous work on touch gesture recognition has focused on the spatio-temporal distribution of normal forces, we hypothesize that the addition of shear forces will permit more reliable classification. We present a soft, flexible skin with an array of tri-axial tactile sensors for the arm of a person or robot. We use it to collect data on 13 touch gesture classes through user studies and train a Convolutional Neural Network (CNN) to learn spatio-temporal features from the recorded data. The network achieved a recognition accuracy of 74% with normal and shear data, compared to 66% using only normal force data. Adding distributed shear data improved classification accuracy for 11 out of 13 touch gesture classes.

Everting, soft growing vine robots benefit from reduced friction with their environment, which allows them to navigate challenging terrain. Vine robots can use air pouches attached to their sides for lateral steering. However, when all pouches are serially connected, the whole robot can only perform one constant curvature in free space. It must contact the environment to navigate through obstacles along paths with multiple turns. This work presents a multi-segment vine robot that can navigate complex paths without interacting with its environment. This is achieved by a new steering method that selectively actuates each single pouch at the tip, providing high degrees of freedom with few control inputs. A small magnetic valve connects each pouch to a pressure supply line. A motorized tip mount uses an interlocking mechanism and motorized rollers on the outer material of the vine robot. As each valve passes through the tip mount, a permanent magnet inside the tip mount opens the valve so the corresponding pouch is connected to the pressure supply line at the same moment. Novel cylindrical pneumatic artificial muscles (cPAMs) are integrated into the vine robot and inflate to a cylindrical shape for improved bending characteristics compared to other state-of-the-art vine robots. The motorized tip mount controls a continuous eversion speed and enables controlled retraction. A final prototype was able to repeatably grow into different shapes and hold these shapes. We predict the path using a model that assumes a piecewise constant curvature along the outside of the multi-segment vine robot. The proposed multi-segment steering method can be extended to other soft continuum robot designs., Comment: Accepted for presentation at the 6th IEEE-RAS International Conference on Soft Robotics (RoboSoft 2023). 7 pages, 12 figures. For associated video, see ancillary files

Summary Fibrosis-driven solid organ failure is an enormous burden on global health. Spiny mice (Acomys) are terrestrial mammals that can regenerate severe skin wounds without scars to avoid predation. Whether spiny mice also regenerate internal organ injuries is unknown. Here, we show that despite equivalent acute obstructive or ischemic kidney injury, spiny mice fully regenerate nephron structure and organ function without fibrosis, whereas C57Bl/6 or CD1 mice progress to complete organ failure with extensive renal fibrosis. Two mechanisms for vertebrate regeneration have been proposed that emphasize either extrinsic (pro-regenerative macrophages) or intrinsic (surviving cells of the organ itself) controls. Comparative transcriptome analysis revealed that the Acomys genome appears poised at the time of injury to initiate regeneration by surviving kidney cells, whereas macrophage accumulation was not detected until about day 7. Thus, we provide evidence for rapid activation of a gene expression signature for regenerative wound healing in the spiny mouse kidney., Graphical abstract, Highlights • Acomys fully regenerate kidney structure and function without fibrosis after injury • Unique gene clusters rapidly activated in surviving cells align with regeneration • Acomys genome appears poised at the time of kidney injury to initiate regeneration, Animal physiology; Molecular biology; Developmental biology

Survivors of central nervous system injury commonly present with spastic hypertonia. The affected muscles are hyperexcitable and can display involuntary static muscle tone and an exaggerated stretch reflex. These symptoms affect posture and disrupt activities of daily living. Symptoms are typically measured using subjective manual tests such as the Modified Ashworth Scale; however, more quantitative measures are necessary to evaluate potential treatments. The hands are one of the most common targets for intervention, but few investigators attempt to quantify symptoms of spastic hypertonia affecting the fingers. We present the isometric force pillow (IFP) to quantify involuntary grip force. This lightweight, computerized tool provides a holistic measure of finger flexion force and can be used in various orientations for clinical testing and to measure the impact of assistive devices.

Augmented reality may benefit medical training by providing visual and haptic feedback as the user manipulates passive materials. We propose a haptic bracelet for feedback in a needle decompression training task, which allows the user to manipulate a physical needle represented in virtual space. As the user inserts the needle through virtual tissue layers, they receive haptic feedback on the wrist depending on the interaction forces at the needle tip. A virtual training environment was created to provide differing haptic feedback when the needle is inserted in locations with a hidden bone representing collision with a rib during the needle decompression task. A pilot study demonstrated that a user can recognize the location of the virtual rib via this haptic feedback; this motivates future work to use this feedback in a medical training system.

Fiber Reinforced Elastomeric Enclosures (FREEs) are soft pneumatic actuators that have been used in haptic devices. These actuators have constraining fibers embedded within them in patterns that determine how they deform when inflated. The existing process of manually embedding these fibers can be both time-consuming and imprecise, so we instead laser cut the constraint from a thin film in a pattern corresponding to the desired actuator behavior. Here, we describe the manufacturing process for an actuator using laser-cut constraints and present the axial force and twisting torque that it produced.

We propose a wrist worn haptic device providing 2-degree-of-freedom shear feedback for haptic guidance during a needle insertion task in mixed reality. We created a training environment to map needle orientation information to the haptic cues acting on the wrist to lead the user towards a desired needle angle. With this system, users can learn to successfully orient a needle before puncturing the skin of a virtual or real tissue at a chosen location while holding a real needle.

Emerging research seeks to apply vibrotactile stimulation in physical therapy to improve diminished limb function. However, for these systems to be accepted, prospective users must find the stimulation tolerable or even pleasant. Prior studies on affective response to stimulation focus on healthy, younger users; older users of new therapeutic applications have different sensory perception than these younger users. Here we queried older adults with and without history of stroke to understand their experience of vibration on the arm at several amplitude-frequency settings and patterns. None of our stimuli were perceived as painful by participants, including two with allodynia who perceive some tactile stimuli as noxious. Individuals with history of stroke reported significantly lower valence ratings but higher arousal ratings than individuals without history of stroke. Lower amplitude stimulation was rated with lower arousal by all participants. Some participants expressed a preference for perceivable or strong stimulation. Reported sensations included tickling, tingling, and numbness.

In this study, we measured wrist torque perception in conditions that mimic activities of daily living. We tested five participants with a two-alternative forced choice paradigm torque comparison test while the user was both seated and walking, with both a stationary and a moving wrist. Reference torque, walking, and moving wrist all significantly affected the results. Both walking and moving wrist conditions resulted in higher Weber fractions (worse perception), and the conditions with the smallest wrist flexion reference torque while walking and moving the wrist had significantly higher Weber fractions than a number of others. This information provides insight regarding the design of wearable kinesthetic haptic devices worn at the wrist.

Resonant frequency skin stretch uses cyclic lateral skin stretches matching the skin's resonant frequency to create highly noticeable stimuli, signifying a new approach for wearable haptic stimulation. Four experiments were performed to explore biomechanical and perceptual aspects of resonant frequency skin stretch. In the first experiment, effective skin resonant frequencies were quantified at the forearm, shank, and foot. In the second experiment, perceived haptic stimuli were characterized for skin stretch actuations across a spectrum of frequencies. In the third experiment, perceived haptic stimuli were characterized by different actuator masses. In the fourth experiment, haptic classification ability was determined as subjects differentiated haptic stimulation cues while sitting, walking, and jogging. Results showed that subjects perceived stimulations at, above, and below the skin's resonant frequency differently: stimulations lower than the skin resonant frequency felt like distinct impacts, stimulations at the skin resonant frequency felt like cyclic skin stretches, and stimulations higher than the skin resonant frequency felt like standard vibrations. Subjects successfully classified stimulations while sitting, walking, and jogging, perceived haptic stimuli was affected by actuator mass, and classification accuracy decreased with increasing speed, especially for stimulations at the shank. This paper could facilitate more widespread use of wearable skin stretch. Potential applications include gaming, medical simulation, and surgical augmentation, and for training to reduce injury risk or improve sports performance.

During interaction with objects using a tool, we experience force and tactile feedback. One form of tactile feedback is local fingerpad skin deformation. In this paper, we provide haptic feedback to users of a teleoperation system through a skin deformation tactile feedback device. The device is able to provide tangential and normal skin deformation in a coupled manner, and is designed so that users can grasp it with a precision grip using multiple fingerpads. By applying skin deformation feedback on multiple fingerpads, the device is able to provide multi-degree-of-freedom interaction force direction and magnitude information to the user. To evaluate the effectiveness of this approach for the performance of teleoperated manipulation tasks, we performed a study in which 20 participants used a teleoperation system to perform one of two manipulation tasks (peg transfer and tube connection) using force feedback, skin deformation feedback, and the combination of both feedback. Results showed that participants are able to use all feedback to improve task performance compared to the case without haptic feedback, although the degree of improvement depended on the nature of the task. The feedback also improved situation awareness, felt consistent with prior experience, and did not affect concentration on the task, as reported by participants.

Haptic devices use touch to enable communication in a salient and private manner. While most haptic devices are held or worn at the hand, there is recent interest in developing wearable haptic devices for the arms. This frees the hands for manipulation tasks, but creates challenges for wearability. One approach is to use pneumatically driven soft haptic devices that, compared to rigid devices, can be more readily worn due to their form factor and light weight. We propose a two-degree of freedom (2-DOF) pneumatic soft linear tactor that can be mounted on the forearm and provide shear force. The tactor is comprised of four soft fiber-constrained linear pneumatic actuators connected to a dome-shaped tactor head. The tactor can provide fast, repeatable forces on the order of 1 N in shear, in various directions in the plane of the skin surface. We demonstrate the tradeoffs of two housing schemes, one soft and one rigid, that mount the pneumatic soft linear actuator to the forearm. A user study demonstrated the performance of both versions of the device in providing directional cues, highlighting the challenges and importance of grounding soft wearable devices and the difficulties of designing haptic devices given the perceptual limits of the human forearm.

Pneumatic wearable haptic devices can provide distributed pressure feedback to human operators during robot teleoperation and in virtual and augmented reality. However, these devices have an inherent trade-off between the spatial coverage of their pressure output and their resolution and dynamic response. To achieve specified spatial resolution and dynamic response, we propose a macro-mini actuation approach that stacks a number of smaller inflatable pouches atop a larger inflatable pouch. We develop models for the static and dynamic responses of single and stacked pouches and compare these with experimental results, providing guidelines for the design of wearable stacked pneumatic displays. Finally, we demonstrate this pneumatic macro-mini approach by replicating the time series pressure profiles of data collected from a huggable robot embedded with distributed force sensors.

Simulating soft robots in cluttered environments remains an open problem due to the challenge of capturing complex dynamics and interactions with the environment. Furthermore, fast simulation is desired for quickly exploring robot behaviors in the context of motion planning. In this paper, we examine a particular class of inflated-beam soft growing robots called "vine robots", and present a dynamics simulator that captures general behaviors, handles robot-object interactions, and runs faster than real time. The simulator framework uses a simplified multi-link, rigid-body model with contact constraints. To narrow the sim-to-real gap, we develop methods for fitting model parameters based on video data of a robot in motion and in contact with an environment. We provide examples of simulations, including several with fit parameters, to show the qualitative and quantitative agreement between simulated and real behaviors. Our work demonstrates the capabilities of this high-speed dynamics simulator and its potential for use in the control of soft robots., Comment: IEEE International Conference on Robotics and Automation, 2021. (Submitted)

Funding Acknowledgements Type of funding sources: None. 【Background】 Patients with pulmonary hypertension (PH) suffer from poor exercise capacity due to impaired oxygenation or reduced cardiac output. However, the relationship between exercise capacity and physical functions remains unclear. 【Purpose】 The purpose of this study is to investigate the relationship between exercise capacity and physical functions in pulmonary hypertension. 【Methods】 From February 2018 to June 2020, 94 patients (61.3 ± 14.7 years old, 69.1% females) with group 1/3/4/5 PH underwent cardiac catheterization, 6-minute walking distance (6MWD), and physical function measurements simultaneously. The physical functions was measured using muscle strength (grip strength, knee extension muscle strength), balance function (one leg standing time), and short physical performance battery (SPPB). Exercise capacity was measured by 6MWD. 【Results】 The study cohort consists of 22/8/60/4 (23.4%/8.5%/63.8%/4.3%) patients with group 1/3/4/5 PH, respectively. The average age of each group was 50.7/64.7/63.1/66.0 years old, respectively. A total of 194 measurements of physical functions were evaluated from 94 patients and employed in multivariate logistic regression analysis using adaptive-LASSO methods with the 6MWD (476.2 ± 107.5m) as a dependent variable. WHO functional class (class II: standardized β=-0.35, 95% confidence interval (CI) [-0.54 - -0.16], p 【Conclusions】 Grip strength and balance function, as well as SvO2 and PVR, were associated with the exercise capacity in pulmonary hypertension.

Due to their ability to move without sliding relative to their environment, soft growing robots are attractive for deploying distributed sensor networks in confined spaces. Sensing of the state of such robots would also add to their capabilities as human-safe, adaptable manipulators. However, incorporation of distributed sensors onto soft growing robots is challenging because it requires an interface between stiff and soft materials, and the sensor network needs to undergo significant strain. In this work, we present a method for adding sensors to soft growing robots that uses flexible printed circuit boards with self-contained units of microcontrollers and sensors encased in a laminate armor that protects them from unsafe curvatures. We demonstrate the ability of this system to relay directional temperature and humidity information in hard-to-access spaces. We also demonstrate and characterize a method for sensing the growing robot shape using inertial measurement units deployed along its length, and develop a mathematical model to predict its accuracy. This work advances the capabilities of soft growing robots, as well as the field of soft robot sensing., Comment: https://www.youtube.com/watch?v=VLT3b9n0vqE&feature

Surgical procedures require a high level of technical skill to ensure efficiency and patient safety. Due to the direct effect of surgeon skill on patient outcomes, the development of cost-effective and realistic training methods is imperative to accelerate skill acquisition. Teleoperated robotic devices allow for intuitive ergonomic control, but the learning curve for these systems remains steep. Recent studies in motor learning have shown that visual or physical exaggeration of errors helps trainees to learn to perform tasks faster and more accurately. In this study, we extended the work from two previous studies to investigate the performance of subjects in different force field training conditions, including convergent (assistive), divergent (resistive), and no force field (null)., Comment: 2 pages, 2 figures, Hamlyn Symposium on Medical Robotics 2019

Intracortical brain-computer interfaces (iBCIs) provide people with paralysis a means to control devices with signals decoded from brain activity. Despite recent impressive advances, these devices still cannot approach able-bodied levels of control. To achieve naturalistic control and improved performance of neural prostheses, iBCIs will likely need to include proprioceptive feedback. With the goal of providing proprioceptive feedback via mechanical haptic stimulation, we aim to understand how haptic stimulation affects motor cortical neurons and ultimately, iBCI control. We provided skin shear haptic stimulation as a substitute for proprioception to the back of the neck of a person with tetraplegia. The neck location was determined via assessment of touch sensitivity using a monofilament test kit. The participant was able to correctly report skin shear at the back of the neck in 8 unique directions with 65% accuracy. We found motor cortical units that exhibited sensory responses to shear stimuli, some of which were strongly tuned to the stimuli and well modeled by cosine-shaped functions. We also demonstrated online iBCI cursor control with continuous skin-shear feedback driven by decoded command signals. Cursor control performance increased slightly but significantly when the participant was given haptic feedback, compared to the purely visual feedback condition.