Development of a Dynamic Knee Actuator for a KAFO Using Superelastic Alloys

2014 ◽  
Author(s):  
Feng Tian ◽  
Mohamed Samir Hefzy ◽  
Mohammad Elahinia
Keyword(s):  
Knee Joint ◽  
Gait Cycle ◽  
Swing Phase ◽  
Walking Ability ◽  
Knee Motion ◽  
Walking Gait ◽  
Ankle Foot Orthosis ◽  
Stance Control ◽  
In Series ◽  
Foot Orthosis

A knee-ankle-foot orthosis (KAFO), which covers the knee, ankle and foot, can mitigate abnormal walking pattern caused by weak quadriceps. Several types of KAFOs are currently available in the market: passive KAFOs, stance-control KAFOs and dynamic KAFOs. In passive KAFOs, the knee joint keeps being locked during standing and walking, and can be unlocked manually to allow free rotation for sitting. Stance-control KAFOs (SCKAFOs) allow free knee motion during swing phase when the braced leg is unloaded. Dynamic KAFOs are able to reproduce normal walking ability throughout whole gait cycle. This research is directed at using superelastic alloys to develop a dynamic knee actuator that can be mounted on a traditional passive KAFO. The actuator stiffness can match that of a normal knee joint during the walking gait cycle. This proposed knee actuator utilizes a storing-releasing energy method to apply functional compensation to the knee joint, controlling the knee joint during both stance and swing phases. Fundamentally, the knee actuator is composed of two distinct parts which are connected with the thigh and shank segments, respectively. There are two superelastic actuators that are housed within these two parts and activated independently. Each actuator is developed by combining a superelastic rod and a rotary spring in series. When neither actuator is engaged, the knee joint is allowed to rotate freely. The stance actuator works only in the stance phase and the swing actuator is active for the swing phase. The conceptual design of the knee actuator is verified using numerical simulation and a prototype is developed through additive manufacturing for confirming the concept.

Design and Evaluation of a Knee Actuator for a Dynamic Knee-Ankle-Foot Orthosis

2014 ◽  
Author(s):  
Feng Tian ◽  
Mohammad Elahinia ◽  
Mohamed Samir Hefzy
Keyword(s):  
Knee Joint ◽  
Gait Cycle ◽  
Gait Pattern ◽  
Walking Ability ◽  
Hydraulic Systems ◽  
Walking Gait ◽  
Normal Knee ◽  
Actuation System ◽  
Normal Gait ◽  
In Series

Dynamic KAFOs are developed to recover the normal walking ability during both stance and swing phases. Three types of dynamic KAFOs have been reported in the literature. Various actuation mechanisms including spring, pneumatic and hydraulic systems have been used. These devices can improve walking disability and compensate lower leg muscle deficiency. However, they are bulky, in some cases need complex control systems and do not recreate the normal gait pattern. These shortcomings have limited the application of dynamic KAFOs in daily life. The purpose of this paper is to develop a novel knee actuator for a dynamic KAFO that is actuated easily by employing shape memory materials. Such an actuation system makes the KAFO lightweight and has a greater potential to restore the normal gait. Torsional superelastic alloys are used in this actuator in order to match the stiffness of the knee joint of the KAFO with that of a normal knee joint during the walking gait cycle. There are two distinct parts in the knee actuator, acting independently to mimic the two phases of the gait cycle. One engages only in the stance phase and the other works in the swing phase. Each part is developed by combining a superelastic rod and a stiff rotary spring, in series. According to numerical simulation, such combination reproduces the varying knee stiffness during the whole walking gait. Also mechanical experiments have been conducted to further verify the conceptual design. The simulation and experimental results show that the actuator is able to reproduce the stiffness of the normal knee joint during the gait cycle.

scholarly journals Newly designed computer controlled knee-ankle-foot orthosis (Intelligent Orthosis)

1998 ◽  
Vol 22 (3) ◽  
pp. 230-239 ◽  
Author(s):  
T. Suga ◽  
O. Kameyama ◽  
R. Ogawa ◽  
M. Matsuura ◽  
H. Oka
Keyword(s):  
Lower Limb ◽  
Stance Phase ◽  
Gait Cycle ◽  
Normal Subjects ◽  
Swing Phase ◽  
Ankle Foot Orthosis ◽  
Normal Gait ◽  
Heel Contact ◽  
Computer Controlled ◽  
Foot Orthosis

The authors have developed a knee-ankle-foot orthosis with a joint unit that controls knee movements using a microcomputer (Intelligent Orthosis). The Intelligent Orthosis was applied to normal subjects and patients, and gait analysis was performed. In the gait cycle, the ratio of the stance phase to the swing phase was less in gait with the knee locked using a knee-ankle-foot orthosis than in gait without an orthosis or gait with the knee controlled by a microcomputer. The ratio of the stance phase to the swing phase between controlled gait and normal gait was similar. For normal subjects the activity of the tibialis anterior was markedly increased from the heel-off phase to the swing phase in locked gait. The muscle activities of the lower limb were lower in controlled force in locked gait showed spikes immediately after heel-contact in the vertical at heel-contact in the sagittal to locked gait, gait with the Intelligent Orthosis is smooth and close to normal gait from the viewpoint of biomechanics. Even in patients with muscle weakness of the quadriceps, control of the knee joint using the Intelligent Orthosis resulted in a more smooth gait with low muscle discharge.

Feasibility of a Powered Knee Joint in Providing Stance and Swing Phase Knee Flexion when Using a Knee-Ankle-Foot Orthosis

2017 ◽  
Vol 29 (4) ◽  
pp. 177-182
Author(s):  
Masoud Rafiaei ◽  
Mokhtar Arazpour ◽  
Mahmood Bahramizadeh ◽  
Farzam Farahmand ◽  
Nima Jamshidi ◽  
...  
Keyword(s):  
Knee Joint ◽  
Knee Flexion ◽  
Swing Phase ◽  
Ankle Foot Orthosis ◽  
Foot Orthosis

Effect of ankle-foot orthosis on level walking in healthy subjects

2019 ◽  
Vol 233 (12) ◽  
pp. 1262-1268
Author(s):  
Mizuki Kato ◽  
Arinori Kamono ◽  
Naomichi Ogihara
Keyword(s):  
Ground Reaction Force ◽  
Healthy Subjects ◽  
Sagittal Plane ◽  
Reaction Force ◽  
Walking Ability ◽  
Vertical Ground Reaction Force ◽  
Walking Gait ◽  
Ankle Foot Orthosis ◽  
Heel Contact ◽  
Foot Orthosis

An ankle-foot orthosis is often prescribed in the rehabilitation of patients with neurological motor disorders such as hemiparesis. However, walking with a unilateral ankle-foot orthosis may not be effectively achieved just by trying to reproduce normal intact walking with a symmetrical gait pattern. Understanding skills to facilitate walking gait with a unilateral ankle-foot orthosis has implications for better rehabilitative interventions to help restore walking ability in patients with stroke. We, therefore, analyzed the kinematics and ground reaction forces of walking with and without an ankle-foot orthosis in healthy subjects to infer the possible skills to facilitate walking gait with a unilateral ankle-foot orthosis. Adult male participants were asked to walk with and without an ankle-foot orthosis across two force platforms set in a wooden walkway, and body kinematics and ground reaction force profiles in the sagittal plane were simultaneously recorded. We found that the forward tilting angle of the trunk at the time of toe-off of the leg with the ankle-foot orthosis was significantly larger than that of the leg without the ankle-foot orthosis, to adaptively compensate for the loss of ankle joint mobility due to the unilateral ankle-foot orthosis. Furthermore, the peak vertical ground reaction force at heel-contact was significantly larger in the leg without the ankle-foot orthosis than in the leg with the ankle-foot orthosis owing to the fact that the stance phase duration of the leg with the ankle-foot orthosis was relatively shorter. Such information may potentially be applied to facilitate walking training in stroke patients wearing a unilateral ankle-foot orthosis.

scholarly journals EFFECT OF KINETIC RETURN ANKLE FOOT ORTHOSIS IN PATIENT WITH INCOMPLETE SPINAL CORD INJURY: CHANGES OF THE GAIT PATTERN. A CASE REPORT

2016 ◽  
Vol 2 (101) ◽  
pp. 8-16
Author(s):  
Margot Bergmann ◽  
Mari Alvela ◽  
Priit Eelmäe ◽  
Doris Vahtrik ◽  
Helena Gapeyeva
Keyword(s):  
Spinal Cord ◽  
Knee Joint ◽  
Ankle Joint ◽  
Gait Pattern ◽  
Swing Phase ◽  
Initial Contact ◽  
Ankle Foot Orthosis ◽  
Foot Progression Angle ◽  
Cord Injury ◽  
Foot Orthosis

Background. The variety of orthotics available induces a purpose for estimation of their influence of functional mobility for individual needs in people with incomplete spinal cord injuries (ISCI). The aim of the study was to investigate the effect of the use of kinetic return ankle foot orthosis (KRAFO) on gait pattern in case of ISCI. Methods. Ankle and knee joint kinematic and kinetic characteristics during gait with and without KRAFO were studied in a 34-year-old man with ISCI (fracture v.C5) using 3D motion analysis system (Vicon Motion Systems Ltd., UK) including two dynamographic platforms (AMTI, USA). Ankle and knee joint angles at initial contact and mid-stance, ankle dorsiflexion and foot progression angle in swing phase and ankle joint push-off values in stance phase were analysed. Results. An excessive dorsiflexion in right ankle joint at initial contact, in mid-stance and in swing-phase occurred when walking without the orthosis, which decreased (105, 57 and 73%, respectively, p < .01) with the use of KRAFO. Orthoses use evoked the decrease (77%, p < .01) in peak foot progression angle. Ankle joint peak push- off power was low without the use of KRAFO and decreased even more (28%, p < .05) with the use of orthosis. Decreases of knee joint flexion angle at initial contact and in mid-stance (29 and 23%, respectively) with the use of KRAFO were not significant as compared to gait without orthosis. Conclusions. Walking with KRAFO improved ankle and knee joint stability, providing a decrease in ankle kinematic characteristics but ankle joint push-off power did not change. Further studies are needed to compare the effect of KRAFO in comparison with other orthoses on gait pattern in case of ISCI in accordance with the patient- centric approach for rehabilitation process management.

The influence of a powered knee–ankle–foot orthosis on walking in poliomyelitis subjects: A pilot study

2015 ◽  
Vol 40 (3) ◽  
pp. 377-383 ◽  
Author(s):  
Mokhtar Arazpour ◽  
Alireza Moradi ◽  
Mohammad Samadian ◽  
Mahmood Bahramizadeh ◽  
Mahmoud Joghtaei ◽  
...  
Keyword(s):  
Knee Joint ◽  
Knee Flexion ◽  
Stance Phase ◽  
Step Length ◽  
Gait Pattern ◽  
Swing Phase ◽  
Ankle Foot Orthosis ◽  
Active Flexion ◽  
Locked Knee ◽  
Foot Orthosis

Background:Traditionally, the anatomical knee joint is locked in extension when walking with a conventional knee–ankle–foot orthosis. A powered knee–ankle–foot orthosis was developed to provide restriction of knee flexion during stance phase and active flexion and extension of the knee during swing phase of gait.Objective:The purpose of this study was to determine differences of the powered knee–ankle–foot orthosis compared to a locked knee–ankle–foot orthosis in kinematic data and temporospatial parameters during ambulation.Study design:Quasi—experimental design.Methods:Subjects with poliomyelitis (n = 7) volunteered for this study and undertook gait analysis with both the powered and the conventional knee–ankle–foot orthoses. Three trials per orthosis were collected while each subject walked along a 6-m walkway using a calibrated six-camera three-dimensional video-based motion analysis system.Results:Walking with the powered knee–ankle–foot orthosis resulted in a significant reduction in both walking speed and step length (both 18%), but a significant increase in stance phase percentage compared to walking with the conventional knee–ankle–foot orthosis. Cadence was not significantly different between the two test conditions ( p = 0.751). There was significantly higher knee flexion during swing phase and increased hip hiking when using the powered orthosis.Conclusion:The new powered orthosis permitted improved knee joint kinematic for knee–ankle–foot orthosis users while providing knee support in stance and active knee motion in swing in the gait cycle. Therefore, the new powered orthosis provided more natural knee flexion during swing for orthosis users compared to the locked knee–ankle–foot orthosis.Clinical relevanceThis orthosis has the potential to improve knee joint kinematics and gait pattern in poliomyelitis subjects during walking activities.

scholarly journals Hybrid Modeling and Fractional Control of a SCKAFO Orthosis for Gait Assistance

2011 ◽  
Author(s):  
S. Hassan HosseinNia ◽  
Francisco Romero ◽  
Blas M. Vinagre ◽  
Francisco Javier Alonso ◽  
Ines Tejado ◽  
...  
Keyword(s):  
Weight Bearing ◽  
Hybrid Modeling ◽  
Knee Motion ◽  
Ankle Foot Orthosis ◽  
Stance Control ◽  
Cord Injury ◽  
Walking Biomechanics ◽  
Control Knee ◽  
Fractional Control ◽  
Foot Orthosis

SCKAFO, stance-control knee-ankle-foot orthosis, is a type of orthosis that permits free knee motion during swing while resisting knee flexion during stance, supporting thereby the limb during weight bearing. This orthosis specially assists patients who have incomplete spinal cord injury and allows them to walk with the aid of canes or crutches, maintaining a proper gait. In this paper, based on the human walking biomechanics, the SCKAFO hybrid modeling is proposed, which consists of eight different stages whose evolution is given by means of four planar sensors on each foot. In the model, it is considered that the patients can move their hip but not their knee that will be controlled using a DC motor. Two fractional order controllers are designed, following decision based control techniques, to control the knee angle. Simulation results are given in order to demonstrate the efficiency of the system performance.

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