Computational and Mathematical Methods in Medicine

Gait Analysis. An Introduction

https://www.mdpi.com/2218-6581/5/2/11/pdf

State of the Art Robotic Grippers and Applications

In the prosthetics field, one of the most important bottlenecks is still the human-machine interface, namely the socket. Indeed, a large number of amputees still rejects prostheses or points out a low satisfaction level, due to a sub-optimal interaction between the socket and the residual limb tissues. The aim of this paper is to describe the main parameters (displacements, stress, volume fluctuations and temperature) affecting the stump-socket interface and reducing the comfort/stability of limb prostheses. In this review, a classification of the different socket types proposed in the literature is reported, together with an analysis of advantages and disadvantages of the different solutions, from multiple viewpoints. The paper then describes the technological solutions available to face an altered distribution of stresses on the residual limb tissues, volume fluctuations affecting the stump overtime and temperature variations affecting the residual tissues within the socket. The open challenges in this research field are highlighted and the possible future routes are discussed, towards the ambitious objective of achieving an advanced socket able to self-adapt in real-time to the complex interplay of factors affecting the stump, during both static and dynamic tasks.

/pdf/sockets-for-limb-prostheses-a-review-of-existing-rl8nuxc0cu.pdf

Sockets for Limb Prostheses: A Review of Existing Technologies and Open Challenges

Recent trends in piezoelectric actuators for precision motion and their applications: a review

Piezoelectric bimorphs have been used as a micro-gripper in many applications, but the system might be complex and the response performance might not have been fully characterized. In this study the dynamic characteristics of bending piezoelectric bimorphs actuators were theoretically and experimentally investigated for micro-gripping applications in terms of deflection along the length, transient response, and frequency response with varying driving voltages and driving signals. In addition, the implementation of a parallel micro-gripper using bending piezoelectric bimorphs was presented. Both fingers were actuated separately to perform mini object handling. The bending piezoelectric bimorphs were fixed as cantilevers and individually driven using a high voltage amplifier and the bimorph deflection was measured using a non contact proximity sensor attached at the tip of one finger. The micro-gripper could perform precise micro-manipulation tasks and could handle objects down to 50 µm in size. This eliminates the need for external actuator extension of the microgripper as the grasping action was achieved directly with the piezoelectric bimorph, thus minimizing the weight and the complexity of the micro-gripper.

https://www.mdpi.com/1424-8220/13/5/5826/pdf

Development of a micro-gripper using piezoelectric bimorphs.

Several studies have presented technological ensembles of active knee systems for transfemoral prosthesis. Other studies have examined the amputees' gait performance while wearing a specific active prosthesis. This paper combined both insights, that is, a technical examination of the components used, with an evaluation of how these improved the gait of respective users. This study aims to offer a quantitative understanding of the potential enhancement derived from strategic integration of core elements in developing an effective device. The study systematically discussed the current technology in active transfemoral prosthesis with respect to its functional walking performance amongst above-knee amputee users, to evaluate the system's efficacy in producing close-to-normal user performance. The performances of its actuator, sensory system, and control technique that are incorporated in each reported system were evaluated separately and numerical comparisons were conducted based on the percentage of amputees' gait deviation from normal gait profile points. The results identified particular components that contributed closest to normal gait parameters. However, the conclusion is limitedly extendable due to the small number of studies. Thus, more clinical validation of the active prosthetic knee technology is needed to better understand the extent of contribution of each component to the most functional development.

/pdf/technology-efficacy-in-active-prosthetic-knees-for-46v45jf109.pdf

Technology Efficacy in Active Prosthetic Knees for Transfemoral Amputees: A Quantitative Evaluation

Alternative sensory systems for the development of prosthetic knees are being increasingly highlighted nowadays, due to the rapid advancements in the field of lower limb prosthetics. This study presents the use of piezoelectric bimorphs as in-socket sensors for transfemoral amputees. An Instron machine was used in the calibration procedure and the corresponding output data were further analyzed to determine the static and dynamic characteristics of the piezoelectric bimorph. The piezoelectric bimorph showed appropriate static operating range, repeatability, hysteresis, and frequency response for application in lower prosthesis, with a force range of 0-100 N. To further validate this finding, an experiment was conducted with a single transfemoral amputee subject to measure the stump/socket pressure using the piezoelectric bimorph embedded inside the socket. The results showed that a maximum interface pressure of about 27 kPa occurred at the anterior proximal site compared to the anterior distal and posterior sites, consistent with values published in other studies. This paper highlighted the capacity of piezoelectric bimorphs to perform as in-socket sensors for transfemoral amputees. However, further experiments are recommended to be conducted with different amputees with different socket types.

/pdf/piezoelectric-bimorphs-characteristics-as-in-socket-sensors-19ludyid2h.pdf

Piezoelectric Bimorphs’ Characteristics as In-Socket Sensors for Transfemoral Amputees

This paper presents an approach of identifying prosthetic knee movements through pattern recognition of mechanical responses at the internal socket's wall. A quadrilateral double socket was custom made and instrumented with two force sensing resistors (FSR) attached to specific anterior and posterior sites of the socket's wall. A second setup was established by attaching three piezoelectric sensors at the anterior distal, anterior proximal, and posterior sites. Gait cycle and locomotion movements such as stair ascent and sit to stand were adopted to characterize the validity of the technique. FSR and piezoelectric outputs were measured with reference to the knee angle during each phase. Piezoelectric sensors could identify the movement of midswing and terminal swing, pre-full standing, pull-up at gait, sit to stand, and stair ascent. In contrast, FSR could estimate the gait cycle stance and swing phases and identify the pre-full standing at sit to stand. FSR showed less variation during sit to stand and stair ascent to sensitively represent the different movement states. The study highlighted the capacity of using in-socket sensors for knee movement identification. In addition, it validated the efficacy of the system and warrants further investigation with more amputee subjects and different sockets types.

/pdf/detection-of-prosthetic-knee-movement-phases-via-in-socket-1wvqipve5x.pdf

Detection of Prosthetic Knee Movement Phases via In-Socket Sensors: A Feasibility Study

The present invention relates to a prosthetic limb (200) integrated with a sensory system (100), comprising of a prosthetic socket (210) for receiving an amputee stump; a lever arm; and an actuator (220); characterized in that said sensory system (100) comprises of a sensing element (120) mounted on the prosthetic socket (210); and a controller (110) connected to the sensing element (120) and the actuator (220), for estimating a gait phase and sending an input signal to the actuator (220) to produce the prosthetic limb (200) movement. The present invention also provides a method of producing the prosthetic limb (200) movement, characterized by the steps of transmitting information from the sensing element (120) to the controller (110); estimating the gait phase using the controller (110), thereby creating the input signal based on the information received from the sensing element (120); sending the input signal from the controller (110) to the actuator (220) to produce the prosthetic limb (200) movement.

Amr M. El-Sayed

Papers

Development of a micro-gripper using piezoelectric bimorphs.

Technology Efficacy in Active Prosthetic Knees for Transfemoral Amputees: A Quantitative Evaluation

Piezoelectric Bimorphs’ Characteristics as In-Socket Sensors for Transfemoral Amputees

Detection of Prosthetic Knee Movement Phases via In-Socket Sensors: A Feasibility Study

A prosthetic limb integrated with a sensory system