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Human tactile afferents provide essential feedback for grasp stability during dexterous object manipulation. Interacting forces between an object and the fingers induce slip events that are thought to provide information about grasp stability. To gain insight into this phenomenon, we made a transparent surface slip against a fixed fingerpad while monitoring skin deformation at the contact. Using microneurography, we simultaneously recorded the activity of single tactile afferents innervating the fingertips. This unique combination allowed us to describe how afferents respond to slip events and to relate their responses to surface deformations taking place inside their receptive fields. We found that all afferents were sensitive to slip events, but FA-I afferents in particular faithfully encoded compressive strain rates resulting from those slips. Given the high density of FA-I afferents in fingerpads, they are well suited to detect incipient slips and to provide essential information for the control of grip force during manipulation.

The study of dexterous manipulation has provided important insights into human sensorimotor control as well as inspiration for manipulation strategies in robotic hands. Previous work focused on experimental environment with restrictions. Here, we describe a method using the deformation and color distribution of the fingernail and its surrounding skin to estimate the fingertip forces, torques, and contact surface curvatures for various objects, including the shape and material of the contact surfaces and the weight of the objects. The proposed method circumvents limitations associated with sensorized objects, gloves, or fixed contact surface type. In addition, compared with previous single finger estimation in an experimental environment, we extend the approach to multiple finger force estimation, which can be used for applications such as human grasping analysis. Four algorithms are used, c.q., Gaussian process, convolutional neural networks, neural networks with fast dropout, and recurrent neural networks with fast dropout, to model a mapping from images to the corresponding labels. The results further show that the proposed method has high accuracy to predict force, torque, and contact surface.

Grip force control during robotic in-hand manipulation is usually modeled as a monolithic task, where complex controllers consider the placement of all fingers and the contact states between each finger and the gripped object in order to compute the necessary forces to be applied by each finger. Such approaches normally rely on object and contact models and do not generalize well to novel manipulation tasks. Here, we propose a modular grip stabilization method based on a proposition that explains how humans achieve grasp stability. In this biomimetic approach, independent tactile grip stabilization controllers ensure that slip does not occur locally at the engaged robot fingers. Local slip is predicted from the tactile signals of each fingertip sensor i.e., BioTac and BioTac SP by Syntouch. We show that stable grasps emerge without any form of central communication when such independent controllers are engaged in the control of multi-digit robotic hands. The resulting grasps are resistant to external perturbations while ensuring stable grips on a wide variety of objects.

Background International medical graduates need to show their proficiencies to obtain a medical license in a new country. In 2016 the Swedish National Board of Health and Welfare redesigned the proficiency test for Doctors of Medicine. The theoretical test consists of around 180 MCQ/SBA. All tests are made public after being used in accordance with the Swedish Public Access to Information and Secrecy Act. Thus, new tests have to be continuously developed. In addition, as a public institution, the test giver is required to reply to all challenges of the items on the test. 

Summary of Work To involve the stakeholders and to improve the quality of the test, the items and corresponding answer keys were made public immediately after the test was finished. The test takers were invited to challenge any item and correct answer via a web form and support challenge with literature references. The item authors then reviewed and replied to each individual challenge. Based on these challenges and the associated review, definitive answer keys were decided. Three weeks after test admission, the test takers received their results, a copy of their test together with correct answers, and the response to their challenges. 

Summary of Results So far, 13 different tests have been given to totally 2,328 test takers. 3,047 challenges were submitted and resulted in 87 changes in answer keys or deletions of an item from the test (3.7% of the 2,360 items across all 13 tests). The number of changes/deletions has decreased significantly with the number of developed tests. 

Discussion & Conclusion We consider the number of test items that have been rejected or adjusted answer keys to be low. Nevertheless, it was necessary to build a system where the challenges from the test takers were built into the test process. In the Swedish educational system appealing a grade is not possible, but if any item in a test is incorrect, the 1992 administrative law requires test givers to promptly adjust test scores. While the implemented process is resource demanding, we believe that it is crucial both for test acceptance among the examinees and to improve the skills of the item authors. 

Take-home Message Involving the test takers in quality assurance of a national licensing test might improve item quality.

Understanding the neurophysiological signals underlying voluntary motor control and decoding them for controlling limb prostheses is one of the major challenges in applied neuroscience and rehabilitation engineering. While pattern recognition of continuous myoelectric (EMG) signals is arguably the most investigated approach for hand prosthesis control, its underlying assumption is poorly supported, i.e., that repeated muscular contractions produce consistent patterns of steady-state EMGs. In fact, it still remains to be shown that pattern recognition-based controllers allow natural control over multiple grasps in hand prosthesis outside well-controlled laboratory settings. Here, we propose an approach that relies on decoding the intended grasp from forearm EMG recordings associated with the onset of muscle contraction as opposed to the steady-state signals. Eight unimpaired individuals and two hand amputees performed four grasping movements with a variety of arm postures while EMG recordings subsequently processed to mimic signals picked up by conventional myoelectric sensors were obtained from their forearms and residual limbs, respectively. Off-line data analyses demonstrated the feasibility of the approach also with respect to the limb position effect. The sampling frequency and length of the classified EMG window that off-line resulted in optimal performance were applied to a controller of a research prosthesis worn by one hand amputee and proved functional in real-time when operated under realistic working conditions.

Det är avgörande att det ställs samma höga krav på läkare från länder utanför EU som på svenskutbildade. Bilden av att det ställs olika krav på olika grupper vore förödande, skriver ansvariga för kunskapsprovet för läkare vid Umeå universitet ihop med Socialstyrelsen.

Background. Reduced sensory feedback from lower leg prostheses results in harmful gait patterns and entails a significant cognitive burden because users have to visually monitor their locomotion. Objectives. The purpose of this study was to validate a sensory feedback device designed to help elderly patients with transfemoral amputation to improve their temporal gait symmetry after a training program aimed at associating the vibrotactile patterns with symmetrical walking. Design. This was a prospective quasi-experimental study including 3 elderly patients walking with lower leg prostheses. Methods. During training sessions, participants walked on a treadmill equipped with feedback device that controlled vibrotactile stimulators based on signals from a sensorized insole while provided with visual feedback about temporal gait symmetry. The vibrotactile stimulators delivered short-lasting, low-intensity vibrations synchronously with certain gait phase transitions. During pretraining and posttraining sessions, participants walked without visual feedback about gait symmetry under 4 conditions: with or without vibrotactile feedback while performing or not performing a secondary cognitive task. The primary outcome measure was temporal gait symmetry. Results. with <= 52 hours of training,the participants improved their temporal gait symmetry from 0.82 to 0.84 during the pretraining evaluation session to 0.98 to 1.02 during the follow-up session across all conditions. Following training, participants were able to maintain good temporal gait synmsetry, without any evidence of an increased cognitive burden. Limitations. The small sample size and short follow-up time do not allow straightforward extrapolations to larger populations or extended time periods. Conclusions. Low-cost, gait phase-specific vibrotactile feedback after training combined with visual feedback may improve the temporal gait synmsetry in patients with transfemoral amputation without representing an additional cognitive burden.

Human grasping and manipulation control critically depends on tactile feedback. Without this feedback, the ability for fine control of a prosthesis is limited in upper limb amputees. Although various approaches have been investigated in the past, at present there is no commercially available device able to restore tactile feedback in upper limb amputees. Based on the Discrete Event-driven Sensory feedback Control (DESC) policy we present a device able to deliver short-lasting vibrotactile feedback to transradial amputees using commercially available myoelectric hands. The device (DESC-glove) comprises sensorized thimbles to be placed on the prosthesis digits, a battery-powered electronic board, and vibrating units embedded in an arm-cuff being transiently activated when the prosthesis makes and breaks contact with objects. The consequences of using the DESC-glove were evaluated in a longitudinal study. Five transradial amputees were equipped with the device for onemonth at home. Through a simple test proposed here for the first time-the virtual eggs test-we demonstrate the effectiveness of the device for prosthetic control in daily life conditions. In the future the device could be easily exploited as an add-on to complement myoelectric prostheses or even embedded in prosthetic sockets to enhance their control by upper limb amputees.

The temporal evolution of surface strain, resulting from a combination of normal and tangential loading forces on the fingerpad, was calculated from high-resolution images. A customized robotic device loaded the fingertip with varying normal force, tangential direction and tangential speed. We observed strain waves that propagated from the periphery to the centre of the contact area. Consequently, different regions of the contact area were subject to varying degrees of compression, stretch and shear. The spatial distribution of both the strains and the strain energy densities depended on the stimulus direction. Additionally, the strains varied with the normal force level and were substantial, e.g. peak strains of 50% with a normal force of 5 N, i.e. at force levels well within the range of common dexterous manipulation tasks. While these observations were consistent with some theoretical predictions from contact mechanics, we also observed substantial deviations as expected given the complex geometry and mechanics of fingertips. Specifically, from in-depth analyses, we conclude that some of these deviations depend on local fingerprint patterns. Our data provide useful information for models of tactile afferent responses and background for the design of novel haptic interfaces.