scholarly journals Biomimetic Design of a Planar Torsional Spring to an Active Knee Prosthesis Actuator Using FEM Analysis

Proceedings ◽  
2020 ◽  
Vol 64 (1) ◽  
pp. 30
Author(s):  
Guilherme Gomes Fiorezi ◽  
Jhonata dos Santos de Moraes ◽  
Pedro Henrique Fabriz Ulhoa ◽  
Rafhael Milanezi de Andrade
Keyword(s):  
Lower Limb ◽  
Material Selection ◽  
Knee Prosthesis ◽  
Angular Displacement ◽  
Mechanical Energy ◽  
Fem Analysis ◽  
Torsional Stiffness ◽  
Healthy Human ◽  
Human Knee ◽  
Torsional Spring

Lower-limb prostheses have an important function to partially recover the leg movement after amputation. In order to improve the mechanical joint behavior towards a healthy human knee, compliant elements have been introduced to the active prostheses, comprised of the well-known Series Elastic Actuators (SEAs). SEAs are used in lower-limb assistive devices due to their ability to tolerate impacts and passive store mechanical energy during ground-walking. Based on the healthy human knee in the stance phase of walking, this paper brings the design, prototyping, and analysis of a customized planar torsional spring. To enhance the compliance of a rigid active knee prosthesis, the proposed spring will substitute a torque flange between the transmission and the output of the actuator, and this carries a series of constraints to the design. The finite element method (FEM) is applied to the development and exploration of the three initially proposed geometries and the material selection along with its heat treatment is based on the maximum stress obtained in the simulations. The proposed geometry, chosen by comparison of the three, is made of austempered AISI 4340 steel and using two springs in parallel and it has a torsional stiffness of 250 N.m/rad with maximum angular displacement of ± 2.5° and 0.153 kg. In future work, we intend to compare the results of the rigid actuator against the SEA one during walking over the ground.

scholarly journals Development and Examination of a Knee Prosthesis Geometry

2019 ◽  
Vol 11 (1) ◽  
pp. 27-30
Author(s):  
Gábor Péter Balassa
Keyword(s):  
Knee Joint ◽  
Research Team ◽  
Knee Prosthesis ◽  
Experimental Measurements ◽  
Joint Movement ◽  
Knee Prostheses ◽  
Healthy Human ◽  
Human Knee ◽  
Human Knee Joint ◽  
Number Of Patients

Abstract The necessity for the knee prosthesis is confirmed by the large increase in the number of patients suffering from arthrosis, which is a present-day disease. Despite this need, there doesn’t exist an optimal knee prosthesis. Nowadays the development of the knee prostheses is progressing. It is very difficult to define the required geometry with traditional methods, because the movement conditions to be created by the prostheses should be similar to the movements of the human knee. During previous research the biomechanical research team of the Szent István University occupied with experimental measurements of the healthy human knee joint movement. In this paper I would like to introduce a method of prosthesis geometry development. As a result, a knee prosthesis geometry has been created which is approaching the movement form of the real human knee joint.

A Review of Use FEM Techniques in Modeling of Human Knee Joint

2016 ◽  
Vol 28 ◽  
pp. 14-25 ◽  
Author(s):  
Nitin Kumar Sahu ◽  
Ajay Kumar Kaviti
Keyword(s):  
Knee Joint ◽  
Knee Replacement ◽  
Knee Prosthesis ◽  
Experimental Studies ◽  
Fem Analysis ◽  
Human Knee ◽  
Replacement Surgery ◽  
Analysis Process ◽  
Human Knee Joint ◽  
Joint Biomechanics

The human knee joint is very critical and complex joint of human body which is responsible for our optimal daily functions. It consists of various bones – femur, tibia, patella, fibula, different ligaments, cartilages, menisci and muscles. FEM is a very useful tool for the analysis of knee joint and various knee replacement products. In the knee replacement surgery a proper understanding of knee joint biomechanics is essential. Because of certain limitations of experimental studies, FEM analysis process is playing a significance role for prominent understanding of knee biomechanics and produced an effective and impressive tool for total knee replacement (TKR/TKA) or partial knee replacement (PKR/PKA). The aim of this paper is to give a review on FEM analysis of human knee joint and knee prosthesis devices and how much adequate this method for these type of analysis.

Design of a Human Knee Reeducation Mechanism

2019 ◽  
Vol 11 (1) ◽  
pp. 42-53
Author(s):  
Allaoua Brahmia ◽  
Ridha Kelaiaia
Keyword(s):  
Lower Limb ◽  
Mechanical Design ◽  
Kinematic Chain ◽  
Lower Limbs ◽  
Kinematic Structure ◽  
Robotic Device ◽  
Human Knee ◽  
Kinematic Study ◽  
Rehabilitation Exercise ◽  
New Machine

Abstract To establish an exercise in open muscular chain rehabilitation (OMC), it is necessary to choose the type of kinematic chain of the mechanical / biomechanical system that constitutes the lower limbs in interaction with the robotic device. Indeed, it’s accepted in biomechanics that a rehabilitation exercise in OMC of the lower limb is performed with a fixed hip and a free foot. Based on these findings, a kinematic structure of a new machine, named Reeduc-Knee, is proposed, and a mechanical design is carried out. The contribution of this work is not limited to the mechanical design of the Reeduc-Knee system. Indeed, to define the minimum parameterizing defining the configuration of the device relative to an absolute reference, a geometric and kinematic study is presented.

scholarly journals Energy absorption at lower limb joints in different foot contact strategies while descending stairs

2021 ◽  
Vol 29 ◽  
pp. 433-440
Author(s):  
Hyeong-Min Jeon ◽  
Ki-Kwang Lee ◽  
Jun-Young Lee ◽  
Ju-Hwan Shin ◽  
Gwang-Moon Eom
Keyword(s):  
Knee Joint ◽  
Potential Energy ◽  
Energy Absorption ◽  
Lower Limb ◽  
Mechanical Energy ◽  
Connective Tissues ◽  
Stair Descent ◽  
Young Subjects ◽  
Power And Energy ◽  
Joint Loads

BACKGROUND: Joint loads in different walking strategies during stair descent have been investigated in terms of the joint moment in association with the risk of osteoarthritis. However, the absorption mechanisms of the potential energy loss are not known. OBJECTIVE: This study aims to compare the mechanical energy absorptions in lower limb joints in different initial foot contact strategies. METHODS: Nineteen young subjects walked down on instrumented stairs with two different strategies, i.e., forefoot and rearfoot strike. Power and energy at lower limb joints during stance phase were compared between strategies. RESULTS: Lower limb joints absorbed 73 ± 11% of the potential energy released by descending stairs and there was no difference between strategies. Rearfoot strategy absorbed less energy than forefoot strategy at the ankle joint in the 1st phase, which was compensated mainly by more energy absorption at the knee in the 2nd phase and less energy generation at the hip joints in the 3rd phase. CONCLUSION: The results suggest that a leg absorbs most of the potential energy while descending stairs irrespective of the walking strategies and that any reduction of energy absorption at one joint is compensated by other joints. Greater energy absorption at the knee joint compared to the other joints suggests high burden of knee joint muscles and connective tissues during stair-descent, which is even more significant for the rearfoot strike strategy.

scholarly journals Automatic Incremental Learning of Terrain Transitions in a Powered Below Knee Prosthesis

2020 ◽  
Author(s):  
Roman Stolyarov ◽  
Hugh Herr ◽  
Matt Carney
Keyword(s):  
Lower Limb ◽  
Incremental Learning ◽  
Prediction Accuracy ◽  
Knee Prosthesis ◽  
Estimation Algorithm ◽  
Limited Sample ◽  
Physiological Conditions ◽  
Lower Limb Prosthesis ◽  
Limb Prosthesis ◽  
High Range

Objective: This paper describes the developmentand preliminary offline validation of an algorithm facilitatingautomatic, self-contained learning of ground terrain transitionsin a lower limb prosthesis. This method allows for continuous,in-field convergence on an optimal terrain prediction accuracyfor a given walking condition, and is thus not limited bythe specific conditions and limited sample size of an in-labtraining scheme. Methods: We asked one subject with a below-kneeamputation to traverse level ground, stairs, and rampsusing a high-range-of-motion powered prosthesis while internalsensor data were remotely logged. We then used these datato develop a dynamic classification algorithm which predictsthe terrain of each stride and then continuously updates thepredictor using both data from the previous stride and anaccurate terrain back-estimation algorithm. Results: Across 100simulations randomizing stride order, our method attained amean next-stride prediction accuracy of ? 96%. This valuewas first reached after ? 200 strides, or about ? 5 minutesof walking. Conclusion and significance: These results demonstratea method for automatically learning the gait patternspreceding terrain transitions in a prosthesis without relyingon any external devices. By virtue of its dynamic learningscheme, application of this method in real-time would allow forcontinuous, in-field optimization of prediction accuracy across avariety of walking variables including physiological conditions,variable terrain geometries, control methodologies, and users.

scholarly journals Dynamic testing of below-knee prosthesis: Assembly and components

1987 ◽  
Vol 11 (3) ◽  
pp. 117-123 ◽  
Author(s):  
H. W. Wevers ◽  
J. P. Durance
Keyword(s):  
Failure Mechanism ◽  
Lower Limb ◽  
Structural Component ◽  
Dynamic Testing ◽  
Knee Prosthesis ◽  
Axial Loading ◽  
The Other ◽  
Normal Gait ◽  
Component Failures ◽  
Lower Limb Amputees

Prosthetic assemblies for lower limb amputees are highly engineered and consist of several components each with its own failure mechanism. This paper describes the dynamic testing of HDPE rotational moulded sockets in a specially designed machine which mimics normal gait. Thus the components are subjected to all main loadings occurring during a stride such as axial loading and A-P bending about the knee and ankle. Machine details as well as the other components of the system are described. SACH feet appear to be vulnerable by rapid wear and structural component failures at less than 100,000 cycles were observed. The sockets are much less vulnerable and stand up to simulated loading of 1350 N for approximately 400,000 cycles. Metal components such as the foot bolt may also fail in fatigue if not properly tightened. References to proposed ISO standards are also included.

scholarly journals FEM Analysis of the Human Knee Joint

2018 ◽  
Author(s):  
Zahra Trad ◽  
Abdelwahed Barkaoui ◽  
Moez Chafra ◽  
João Manuel R.S. Tavares
Keyword(s):  
Knee Joint ◽  
Fem Analysis ◽  
Human Knee ◽  
Human Knee Joint

scholarly journals Active plantar-flexion above-knee prosthesis: Concept and preliminary design

1985 ◽  
Vol 9 (3) ◽  
pp. 141-144 ◽  
Author(s):  
C. Rigas
Keyword(s):  
Lower Limb ◽  
Knee Prosthesis ◽  
Plantar Flexion ◽  
High Mass ◽  
Energy Output ◽  
Promising Alternative ◽  
Power Sources ◽  
Ankle Joints ◽  
External Power ◽  
Lower Limb Prostheses

Lower limb prostheses produced so far do not replace the function of the musculature, which provides the necessary amount and the proper distribution of energy to the ambulatory mechanism. Provision of external power to lower limb prostheses has been hindered by the fact that the large amount of energy needed at a lower limb necessitates the use of external power sources of unacceptably high mass and volume. Self energized mechanisms offer a promising alternative to the problem. Normally a large part of energy output during locomotion appears at the ankle joint. It seems therefore desirable to develop an above-knee prosthesis featuring active plantar-flexion at the ankle. Energy may be offered by a self energized system. The system, described here, accumulates energy during the passive movements of the knee and ankle joints and stores it for later use at the ankle.

scholarly journals Foot loading in amputee stance

1984 ◽  
Vol 8 (3) ◽  
pp. 159-164 ◽  
Author(s):  
M. Lord ◽  
D. M. Smith
Keyword(s):  
Body Weight ◽  
Lower Limb ◽  
Normative Data ◽  
Knee Prosthesis ◽  
Background Information ◽  
Clinical Environment ◽  
Training School ◽  
Number Of Patients ◽  
Foot Loading ◽  
Provide Background Information

A survey has been carried out to establish information on foot loading in amputee stance. The parameters measured are percentage body weight and the positions of the centres of pressure under each foot. The data was collected in a clinical environment by the use of a Double Video Forceplate (DVF), a tool developed at the Bioengineering Centre. The objective of the survey is to provide background information for the use of the DVF in static alignment of lower-limb prostheses. Results are presented from a number of patients attending the Roehampton Walking Training School, and for a small group of patients attending the Bioengineering Centre for delivery of an experimental below-knee prosthesis. Scattergrams and averaged results provide normative data which can assist in interpretation of DVF displays during individual alignment.

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