scholarly journals Effect of Ankle Torque on the Ankle–Foot Orthosis Joint Design Sustainability

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2975
Author(s):  
Pruthvi Serrao ◽  
Vivek Kumar Dhimole ◽  
Chongdu Cho
Keyword(s):  
Ankle Joint ◽  
Material Selection ◽  
Functional Requirements ◽  
Element Analysis ◽  
Ankle Foot Orthosis ◽  
Prominent Component ◽  
Transfer Capability ◽  
Gear Mechanism ◽  
Dynamic Loading Conditions ◽  
Foot Orthosis

The ankle joint of a powered ankle–foot orthosis (PAFO) is a prominent component, as it must withstand the dynamic loading conditions during its service time, while delivering all the functional requirements such as reducing the metabolic effort during walking, minimizing the stress on the user’s joint, and improving the gait stability of the impaired subjects. More often, the life of an AFO is limited by the performance of its joint; hence, a careful design consideration and material selection are required to increase the AFO’s service life. In the present work, a compact AFO joint was designed based on a worm gear mechanism with steel and brass counterparts due to the fact of its large torque transfer capability in a single stage, enabling a compact joint. Further, it provided an added advantage of self-locking due to the large friction that prevents backdrive, which is beneficial for drop-foot recovery. The design was verified using nonlinear finite element analysis for maximum torque situations at the ankle joint during normal walking. The results indicate stress levels within its design performance; however, it is recommended to select high-grade structural steel for the ankle shaft as the highest stresses in AFO were located on it.

PROPULSION SYSTEM WITH PNEUMATIC ARTIFICIAL MUSCLES FOR POWERING ANKLE-FOOT ORTHOSIS

2013 ◽  
Vol 43 (4) ◽  
pp. 3-16 ◽  
Author(s):  
Ivanka Veneva ◽  
Bram Vanderborght ◽  
Dirk Lefeber ◽  
Pierre Cherelle
Keyword(s):  
Ankle Joint ◽  
Position Control ◽  
Human Motion ◽  
Propulsion System ◽  
Joint Torque ◽  
Joint Control ◽  
Artificial Muscles ◽  
Ankle Foot Orthosis ◽  
Pneumatic Artificial Muscles ◽  
Foot Orthosis

Abstract The aim of this paper is to present the design of device for control of new propulsion system with pneumatic artificial muscles. The propulsion system can be used for ankle joint articulation, for assisting and rehabilitation in cases of injured ankle-foot complex, stroke patients or elderly with functional weakness. Proposed device for control is composed by microcontroller, generator for muscles contractions and sensor system. The microcontroller receives the control signals from sensors and modulates ankle joint flex- ion and extension during human motion. The local joint control with a PID (Proportional-Integral Derivative) position feedback directly calculates desired pressure levels and dictates the necessary contractions. The main goal is to achieve an adaptation of the system and provide the necessary joint torque using position control with feedback.

An Automated Testing Assembly for Characterizing Stiffness of an Ankle Foot Orthosis

2011 ◽  
Author(s):  
Minal Y. Bhadane ◽  
Charles Armstrong ◽  
Mohamed Samir Hefzy ◽  
Mohammad H. Elahinia
Keyword(s):  
Ankle Joint ◽  
Automated Testing ◽  
Time Data ◽  
Angle Sensor ◽  
Ankle Foot Orthosis ◽  
Ankle Stiffness ◽  
Stiffness Variation ◽  
Stiffness Characteristics ◽  
Foot Orthosis ◽  
Testing Assembly

An ankle foot orthosis (AFO) is a device that provides a controlled force to compensate for the muscle deficiencies in the ankle and helps normalize the gait of the patient. Evidence has indicated that there exists an optimal match correlating the patient’s gait related problems and the AFO stiffness. AFO ankle stiffness is measured by the moment around the ankle joint exerted by the AFO per degree of ankle joint rotation. To date, several testing devices and procedures have been developed to assess the stiffness characteristics of AFOs. Most of the devices are manually driven and may not exactly replicate human leg motion. Objective of developing an automated testing assembly is to identify stiffness characteristics of passive AFOs so as to develop an active AFO with shape memory alloy. We have developed an assembly using aluminum T-slotted profiles, single flange linear bearings, and living hinges from 80/20 Inc. Angle measurement was done by mounting Digital Protractor on the shank segment. The whole assembly was mounted on BOSE ElectroForce 3330 test instrument. dSPACE hardware-in-the-loop solution was used for real time data capture of force and angle sensor output. After assessing the characteristics of passive AFO we incorporated SMA wire in the AFO. Similar tests were conducted to evaluate effect of SMA wires on the overall stiffness of an AFO. The results confirm that SMA wires provide stiffness variation such a way that AAFO can be developed to achieve stiffness variation close to normal ankle stiffness.

scholarly journals A Model to Predict the Effect of Ankle Joint Misalignment on Calf Band Movement in Ankle-Foot Orthoses

2007 ◽  
Vol 31 (1) ◽  
pp. 76-87 ◽  
Author(s):  
Stefania Fatone ◽  
Andrew H. Hansen
Keyword(s):  
Ankle Joint ◽  
Walking Speed ◽  
Sagittal Plane ◽  
Plantar Flexion ◽  
Dimensional Model ◽  
Ankle Foot Orthosis ◽  
Ankle Joints ◽  
Ankle Foot Orthoses ◽  
Foot Orthosis ◽  
Anterior Posterior

Accurate alignment of anatomical and mechanical joint axes is one of the major biomechanical principles pertaining to articulated orthoses, yet knowledge of the potential effects of axis misalignment is limited. The purpose of this project was to model the effects of systematic linear (proximal-distal and anterior-posterior) misalignments of single axis mechanical ankle joints in an ankle-foot orthosis (AFO) in order to determine the degree and direction of calf band travel that would occur over a functional range of motion. Sagittal plane misalignments of the ankle joint centres of an AFO were simulated using a simple two-dimensional model for both a range of ankle angles and a typical able-bodied ankle kinematic curve for self-selected normal walking speed. The model assumed that no movement occurred between the foot and the foot-plate of the AFO. The model predicted that for anterior (positive horizontal) misalignments, dorsiflexion movements would cause the calf band to travel proximally (i.e., up the leg) and plantar flexion movements would cause the calf band to travel distally (i.e., down the leg). The opposite was predicted for posterior (negative horizontal) misalignments. Proximal (positive vertical) misalignments would cause only distal movements of the calf band while distal (negative vertical) misalignments would cause only proximal movements of the calf band. Anterior-posterior misalignments were found to have a much larger effect on the amount of calf band travel than proximal-distal misalignments.

scholarly journals Ankle-foot Orthosis With an Oil Damper Versus Nonarticulated Ankle-foot Orthosis in the Gait of Patients With Subacute Stroke: A Randomized Controlled Trial

2021 ◽  
Author(s):  
Sumiko Yamamoto ◽  
Naoyuki Motojima ◽  
Yosuke Kobayashi ◽  
Yuji Osada ◽  
Souji Tanaka ◽  
...  
Keyword(s):  
Power Generation ◽  
Randomized Controlled Trial ◽  
Ankle Joint ◽  
Controlled Trial ◽  
Plantar Flexion ◽  
Vertical Angle ◽  
Power Absorption ◽  
Ankle Foot Orthosis ◽  
Randomized Controlled ◽  
Foot Orthosis

Abstract BackgroundGait improvement in patients with stroke using ankle-foot orthosis (AFO) has been compared to the effects of non-AFO use in previous studies, but the effect of different kinds of AFOs has not been clear. When considering the effect of different kinds of AFOs on gait, the dorsiflexion and plantar flexion moment of resistance is considered a key determinant of functional effect. In this study, the effect on gait of using an AFO with an oil damper (AFO-OD), which has plantar flexion resistance but no dorsiflexion resistance, and a nonarticulated AFO, which has both dorsiflexion and plantar flexion resistance, were compared in a randomized controlled trial. MethodsForty-one patients (31 men, 10 women; mean age 58.4 ± 11.3 years) in the subacute phase of stroke were randomly allocated to two groups to undergo 2 weeks of gait training by physiotherapists while wearing an AFO-OD or a nonarticulated AFO. A motion capture system was utilized to measure shod gait without orthosis at baseline and after training with the allocated AFO. Data analysis was performed focused on the spatial and temporal parameters, ground reaction force, shank-to-vertical angle, and ankle joint kinematics and kinetics. Two-way mixed ANOVA was performed to clarify the effect of AFO use and the difference between the two AFOs. ResultsThirty-six patients completed the study (17 in the AFO-OD group and 19 in the nonarticulated AFO group). Spatial and temporal parameters and ankle joint kinematics were improved after 2 weeks in both AFO groups. Interactions were found for the range of shank-to-vertical angles in paretic single stance and ankle peak power absorption. In the AFO-OD group, both parameters improved when the participants walked with the AFO compared to the shod gait, but there was no change in the nonarticulated AFO group. Power generation was not increased in either AFO group. ConclusionsThe results of this study showed that AFO with plantar flexion resistance but without dorsiflexion resistance improved the range of the shank-to-vertical angle and ankle power absorption but not power generation in a paretic stance. (336/350 words)Trial registration: UMIN000028126 Registered 1 August 2017,https://upload.umin.ac.jp/cgi-bin/icdr/ctr_menu_form_reg.cgi?recptno=R000032197

KINETIC EFFECTS OF A LOCKED ANKLE JOINT VIA AN ANKLE-FOOT ORTHOSIS DURING WALKING

1999 ◽  
Vol 31 (Supplement) ◽  
pp. S130
Author(s):  
S. M. Clark-Donovan ◽  
J. A. Crussemeyer ◽  
J. S. Dufek ◽  
B. T. Bates
Keyword(s):  
Ankle Joint ◽  
Ankle Foot Orthosis ◽  
Kinetic Effects ◽  
Foot Orthosis

Stiffness Analysis of a Simplified Ankle-Foot Orthosis

2020 ◽  
Author(s):  
Ethan Swierski ◽  
Molly Burke ◽  
Maria Arenas ◽  
Jessica Bernat ◽  
James Manzer ◽  
...  
Keyword(s):  
Design Process ◽  
Laser Cutting ◽  
High Performance ◽  
Low Cost ◽  
Walking Ability ◽  
Thermoplastic Resin ◽  
Element Analysis ◽  
Ankle Foot Orthosis ◽  
The Impact ◽  
Foot Orthosis

Abstract Due to the impact gait impairments have on afflicted individuals’ lives, there are many efforts to find effective remedies. One example is drop foot, a condition in which the dorsiflexion in the leg falters, and the forefront of the foot drags during walking. One of these is the use of an Ankle Foot Orthosis (AFO), a device worn on the lower extremity of the leg to improve walking ability. Although these orthoses have been improved over time to address a user’s physical needs, material and financial restrictions are still an obstacle. To find the lowest cost AFO design of high performance, a study was conducted to investigate the applications of a simplified design process for an AFO. The design process is a fast, low cost, easy technique of laser cutting thermoplastic resin and bending a drawing into a 3-dimensional AFO. Finding the best AFO possible using this design process was easy, involving making a 2-dimensional CAD model for laser cutting, performing Finite Element Analysis (FEA) simulations and comparing a variety of designs, materials, and configurations for their ability to improve a user’s gait kinematics while also meeting optimal cost and comfort needs.

Effects of joint alignment and type on mechanical properties of thermoplastic articulated ankle-foot orthosis

2011 ◽  
Vol 35 (2) ◽  
pp. 181-189 ◽  
Author(s):  
Fan Gao ◽  
William Carlton ◽  
Susan Kapp
Keyword(s):  
Mechanical Properties ◽  
Ankle Joint ◽  
Plantar Flexion ◽  
Skin Irritation ◽  
Neutral Position ◽  
Motor Shaft ◽  
Ankle Foot Orthosis ◽  
Resistance Torque ◽  
Flexure Joints ◽  
Foot Orthosis

Background: Articulated or hinged ankle-foot orthosis (AFO) allow more range of motion. However, quantitative investigation on articulated AFO is still sparse.Objective: The objective of the study was to quantitatively investigate effects of alignment and joint types on mechanical properties of the thermoplastic articulated AFO.Study design: Tamarack dorsiflexion assist flexure joints with three durometers (75, 85 and 95) and free motion joint were tested. The AFO joint was aligned with the center of the motor shaft (surrogate ankle joint), 10 mm superior, inferior, anterior and posterior with respect to the motor shaft center.Methods: The AFO was passively moved from 20° plantar flexion to 15° dorsiflexion at a speed of 10°/s using a motorized device. Mechanical properties including index of hysteresis, passive resistance torque and quasi-static stiffness (at neutral, 5°, 10° and 15° in plantar flexion) were quantified.Results: Significant effects of joint types and joint alignment on the mechanical properties of an articulated thermoplastic AFO were revealed. Specifically, center alignment showed minimum resistance and stiffness while anterior and posterior alignment showed significantly higher resistance and stiffness. The dorsiflexion assist torques at neutral position ranged from 0.69 ± 0.09 to 1.88 ± 0.10 Nm.Conclusions: Anterior and posterior alignment should be avoided as much as possible.Clinical relevanceThe current study suggested that anterior and posterior alignment be avoided as much as possible in clinical practice due to potential skin irritation and increase in stress around the ankle joint.

Ankle–foot orthosis design between the tradition and the computerized perspectives

2019 ◽  
Vol 43 (5) ◽  
pp. 354-361
Author(s):  
Ayham Darwich ◽  
Hasan Nazha ◽  
Aleen Sliman ◽  
William Abbas
Keyword(s):  
Numerical Models ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Material Loss ◽  
Ankle Foot Orthosis ◽  
Engineering Software ◽  
Numerical Design ◽  
Dynamic Loading Conditions ◽  
Design And Testing ◽  
Foot Orthosis

This study focuses on the drop foot case related to hyperthyroidism of the ankle joint resulting in the relaxation of the toes during walking. This condition requires treatment using an ankle–foot orthosis. Traditional orthosis techniques lack precision and depend on the skill of the fabricator. This research aims to make a bias in ankle–foot orthosis design and analysis methods, where a complete methodology of numerical design and testing has been proposed using advanced engineering software. A numerical model of the patient’s foot was generated and used to design an ankle–foot orthosis model using SolidWorks. The designed model was mechanically analyzed by the finite element method using ANSYS Workbench 16.1 under different static and dynamic loading conditions. The ankle–foot orthosis model was numerically designed and analyzed before the manufacturing process. This is believed to reduce time and material loss and foster the use of numerical models in biomedical applications. This study suggests focusing on the design and analysis of orthoses according to the patient’s measurements. This is expected to increase the comfort and raise the level of treatment. Numerical design methods also enable precise manufacturing using computerized devices such as three-dimensional printers.

scholarly journals A Portable Ankle-Foot Rehabilitation Orthosis Powered by Electric Motor

2015 ◽  
Vol 9 (1) ◽  
pp. 982-991 ◽  
Author(s):  
Yang Bai ◽  
Xueshan Gao ◽  
Jun Zhao ◽  
Fei Jin ◽  
Fuquan Dai ◽  
...  
Keyword(s):  
Ankle Joint ◽  
Electric Motor ◽  
Plantar Flexion ◽  
Structure Design ◽  
Foot Drop ◽  
Installation Space ◽  
Joint Movement ◽  
Loop Control ◽  
Ankle Foot Orthosis ◽  
Foot Orthosis

Powered ankle-foot orthosis can not only prevent foot-drop and assist patients’ walking but also improve the ankle joint movement for patients with dysfunction caused by the various injuries and nervous system diseases. Common ankle rehabilitation devices limit the ankle injury patients’ rehabilitation training within fixed places, so a portable powered ankle-foot orthosis is presented in this paper to enable the patients to continue their work normally with the treatment. The orthosis employs electric motor drive mode to provide ankle dorsiflexion and plantar flexion assistance during patient’s walking. First, the ankle-foot dynamics model is established and the gait is analyzed for the powered ankle-foot orthosis system. Then, a new mechanical structure including wearing parts, analogous ankle joint and transmission is described. For the small installation space between the instep and the knee, the compact transmission mechanism has been given more attention and the finite element method is adopted to optimize the key structure after the force analysis. In addition, the closed-loop control system is chosen for the orthosis position and speed control. At last, wearing and movement experiments on the prototype are carried out, which validates the stability and rationality of the structure design and the effectiveness of the motion control. It has great significance in promoting patient's rehabilitation to help them return to the society.

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