Multilevel control of an anthropomorphic prosthetic hand for grasp and slip prevention

The success of grasping and manipulation tasks of commercial prosthetic hands is mainly related to amputee visual feedback since they are not provided either with tactile sensors or with sophisticated control. As a consequence, slippage and object falls often occur. This article wants to address the specific issue of enhancing grasping and manipulation capabilities of existing prosthetic hands, by changing the control strategy. For this purpose, it proposes a multilevel control based on two distinct levels consisting of (1) a policy search learning algorithm combined with central pattern generators in the higher level and (2) a parallel force/position control managing slippage events in the lower level. The control has been tested on an anthropomorphic robotic hand with prosthetic features (the IH2 hand) equipped with force sensors. Bi-digital and tri-digital grasping tasks with and without slip information have been carried out. The KUKA-LWR has been employed to perturb the grasp stability inducing controlled slip events. The acquired data demonstrate that the proposed control has the potential to adapt to changes in the environment and guarantees grasp stability, by avoiding object fall thanks to prompt slippage event detection

Survey of transfemoral amputee experience and priorities for the user-centered design of powered robotic transfemoral prostheses

BACKGROUND: Transfemoral amputees experience a complex host of physical, psychological, and social challenges, compounded by the functional limitations of current transfemoral prostheses. However, the specific relationships between human factors and prosthesis design and performance characteristics have not yet been adequately investigated. The present study aims to address this knowledge gap. METHODS: A comprehensive single-cohort survey of 114 unilateral transfemoral amputees addressed a broad range of demographic and clinical characteristics, functional autonomy, satisfaction and attitudes towards their current prostheses, and design priorities for an ideal transfemoral prosthesis, including the possibility of active assistance from a robotic knee unit. The survey was custom-developed based on several standard questionnaires used to assess motor abilities and autonomy in activities of daily living, prosthesis satisfaction, and quality of life in lower-limb amputees. Survey data were analyzed to compare the experience (including autonomy and satisfaction) and design priorities of users of transfemoral prostheses with versus without microprocessor-controlled knee units (MPKs and NMPKs, respectively), with a subsequent analyses of cross-category correlation, principal component analysis (PCA), cost-sensitivity segmentation, and unsupervised K-means clustering applied within the most cost-sensitive participants, to identify functional groupings of users with respect to their design priorities. RESULTS: The cohort featured predominantly younger (< 50 years) traumatic male amputees with respect to the general transfemoral amputee population, with pronounced differences in age distribution and amputation etiology (traumatic vs. non-traumatic) between MPK and NMPK groups. These differences were further reflected in user experience, with MPK users reporting significantly greater overall functional autonomy, satisfaction, and sense of prosthesis ownership than those with NMPKs, in conjunction with a decreased incidence of instability and falls. Across all participants, the leading functional priorities for an ideal transfemoral prosthesis were overall stability, adaptability to variable walking velocity, and lifestyle-related functionality, while the highest-prioritized general characteristics were reliability, comfort, and weight, with highly variable prioritization of cost according to reimbursement status. PCA and user clustering analyses revealed the possibility for functionally relevant groupings of prosthesis features and users, based on their differential prioritization of these features—with implications towards prosthesis design tradeoffs. CONCLUSIONS: This study’s findings support the understanding that when appropriately prescribed according to patient characteristics and needs in the context of a proactive rehabilitation program, advanced transfemoral prostheses promote patient mobility, autonomy, and overall health. Survey data indicate overall stability, modularity, and versatility as key design priorities for the continued development of transfemoral prosthesis technology. Finally, observed associations between prosthesis type, user experience, and attitudes concerning prosthesis ownership suggest both that prosthesis characteristics influence device acceptance and functional outcomes, and that psychosocial factors should be specifically and proactively addressed during the rehabilitation process. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12984-021-00944-x

DESIGN OF A NEW EMG SENSOR FOR UPPER LIMB PROSTHETIC CONTROL AND REAL TIME FREQUENCY ANALYSIS

Myoelectric prosthesis are aids that try to give back to patients a bit of autonomy and indipendence in their life. Several control techniques were explored in the past, but still the electromyographic (EMG) control remains the most widely used method. Most of the commercial EMG electrodes for prosthetic control available on the market modify the acquired signal acting a heavy frequency filtering, making the signal more clear and better suitable for prosthetic control even if the information related to its frequency behaviour are lost. This information instead would be precious for a frequency analysis, to face and solve the problem of musclular fatigue, an effect that arises in case both of repetitive movements and sustained isometric contraction, as literature reports, causing an amplitude increasing and a spectrum shift toward lower frequencies of the EMG signal. This, in turn, can cause problems in the control of myoelectric prostheses [1]. The aim of this work is hence to illustrate the design of a new EMG electrode suitable both for prosthetic control and frequency analisys, taking into account the problem of muscular fatigue

VR-Wheel: a rehabilitation platform for motor recovery

In this paper we introduce VR-Wheel, a platform combining cognitive and motor-learning tasks, intended for motor recovery in lower limb amputee and tetraplegic patients in post-traumatic conditions. The main feature of the platform is its versatility from the biomechanical, hardware and software viewpoint, since the design of the application is such that patients\u2019 own wheelchairs are transformed into an USB mouse, interfaced with any types of mouse-drivable graphics and/or software and any kind of operative system. The mechanics is flexible and the dedicated VR-environment is user friendly and easily tunable to different, specific clinical requirements. In this paper we present its general design and some scenarios for its clinical use

A New Sustainable Soft Body Protector for Increasing Human Safety in Combat Sports: The Case of Taekwondo

Taekwondo is a martial art recognized as an Olympic sport since 2000. During competitions, athletes wear the typical protective garment composed by head, arms, hands, trunk, genitals, legs, foot protectors. The trunk protector has been developed with several modifications during history adding electronic devices to help referees in the points’ assignment. In this paper, some recent technologies adopted in body protectors are analyzed with the purpose of modelling an innovative sustainable soft body protector specific for Taekwondo competitions. The proposed body protector is composed of internal embedded pneumatic devices to increase safety from injuries and reducing transmissibility of a kick or punch on the human’s trunk. Making use of FEM analysis, several geometries of this device are examined to guarantee a high protection level. Some comparison on transmissibility of the impact on the human’s trunk with our solutions and available results in literature of an electronic body protector on market underline the very good results obtained with our proposal. The transmissibility is reduced of 70% using the commercial product and of 30% using our engineering simulation. The excellent results open-up a new sustainable research field in the wearable protection systems. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG

PERFORMANCE EVALUATION OF THE NEW OTTO BOCK “DynamicArm” BY MEANS OF BIOMECHANICAL MODELLING

Through infra-red motion analysis systems it is possible to acquire the 3D joint kinematics of a patient while performing every day activities. These data, combined with a biomechanical model of the anatomical structures under investigation and clinical rating scales, can form the basis for an objective assessment of the patient motor ability. When the subject acquired is an amputee fitted with a new prosthetic arm, the information provided can be useful not only for the practitioner but also for the prosthesis designer. The aim of this work is to give an example of this kind of clinical/technology assessment, presenting the results obtained for a young trans-humeral amputee fitted with a prototype of the new Otto Bock DynamicArm. In particular, the analysis intended to quantitatively evaluate: 1) the performances of the Otto Bock arm, and in particular of the electromechanic elbow, when controlled in-vivo by the patient EMG signals; 2) how the patient controls the prosthesis, in order to identify critical movements and prevent possible disorders; 3) if the new prosthesis increases the patient abilities

Sistema di aggancio per collegare elettricamente un dispositivo elettronico con un sensore tessile

È descritto un sistema di aggancio in continuità elettrica con elettrodi tessili, detto sistemadiagganciocomprendendo:-una scocca contenitiva comprendente una sede adatta a ricevere un dispositivo elettronico ed almeno un connettore metallico; in cui il connettore metallico comprende: - una parte superiore avente una conformazione sostanzialmente allungata ed estendentisi attraverso il fondo della sede, detta parte superiore essendo adatta a collegarsi elettricamente con detto dispositivo elettronico;- una parte centrale sostanzialmente piatta ed impegnata ad una estremità di detta parte superiore, detta parte centrale essendo adatta a bloccare meccanicamente il connettore metallico tra un tessuto e la scocca contenitiva;- una parte inferiore comprendente una pluralità di elementi cilindrici, in cui ciascun elemento cilindrico si estende, da detta parte centrale, in direzione opposta rispetto a detta parte superiore; in cui ciascun elemento cilindrico è configurato per penetrare in un sensore tessile formando una connessione sia elettrica sia meccanica

Soft Tissue Artefact Assessment in Humeral Axial Rotation

The accuracy of upper-limb kinematic data acquired from optoelectronic systems with retro-reflective markers is poor, mainly due to soft tissue artefact (STA). For the upper-arm, humeral internal/external rotation (HIER) is the movement most affected by STA, which is measured as a percentile fraction (K) of the effective humeral axial rotation performed. The aim of this work was to quantify STA during HIERs, with independently varying attitude of the humerus and elbow flexion, and to test the possibility of estimating its mean value over the tested upper-limb orientations using one simple trial. Six able-bodied subjects performed a series of HIERs in combination with elbow flexion for different humeral planes and degrees of elevation. During the trials the instantaneous attitudes of two humeral anatomical frames were compared, one being affected by the STA to be measured, and the other assumed as the gold standard. K was found to range from 20% to 48% of the effective humeral axial rotation performed, depending on the subject, humeral attitude and elbow flexion. These last two factors comparably affect STA and resulted in mean K coefficients of variation among the subjects of about 9% and 7%, respectively. Common patterns of K with elbow flexion and humerus elevation are discussed. The data also show that the mean of K of a subject is very close to the value assessed in a specific upper-limb configuration consistent among the subjects. This result from this study could be used to build up a time-saving STA compensation procedure suitable for clinical applications