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.

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.

A Biologically Inspired Knee Actuator for a KAFO

2016 ◽  
Vol 10 (4) ◽  
Author(s):  
Feng Tian ◽  
Mohamed Samir Hefzy ◽  
Mohammad Elahinia
Keyword(s):  
Knee Joint ◽  
Knee Flexion ◽  
Gait Cycle ◽  
Knee Extension ◽  
Lateral Side ◽  
Walking Gait ◽  
Normal Knee ◽  
Knee Stiffness ◽  
Control Knee ◽  
Stiffness Profile

Knee–ankle–foot orthoses (KAFOs) are prescribed to improve abnormal ambulation caused by quadriceps weakness. There are three major types of KAFOs: passive KAFOs, semidynamic KAFOs, and dynamic KAFOs. Dynamic KAFOs are the only type that enables to control knee motions throughout the entire walking gait cycle. However, those available in the market are heavy, bulky, and have limited functionality. The UT dynamic KAFO is developed to allow knee flexion and assist knee extension over the gait cycle by using a superelastic nitinol actuator, which has the potential to reduce volume and weight and reproduce normal knee behavior. In order to match the normal knee stiffness profile, the dynamic actuator consists of two actuating parts that work in the stance and swing phases, respectively. Each actuating part combines a superelastic torsional rod and a torsional spring in parallel. Geometries of the two superelastic rods were determined by matlab-based numerical simulations. The simulation response of the dynamic actuator was compared with the normal knee stiffness, verifying that the proposed design is able to mimic the normal knee performance. The surrounding parts of the dynamic knee joint have then been designed and modeled to house the two actuating parts. The dynamic knee joint was fabricated and mounted on a conventional passive KAFO, replacing its original knee joint on the lateral side. Motion analysis tests were conducted on a healthy subject to evaluate the feasibility of the UT dynamic KAFO. The results indicate that the UT dynamic KAFO allows knee flexion during the swing phase of gait and provides knee motion close to normal.

A Dynamic Knee-Ankle-Foot Orthosis With Superelastic Actuators

2013 ◽  
Author(s):  
Feng Tian ◽  
Mohammad Elahinia ◽  
Mohamed Samir Hefzy
Keyword(s):  
Knee Joint ◽  
Shape Memory ◽  
Conceptual Design ◽  
Stance Phase ◽  
Gait Cycle ◽  
Joint Rotation ◽  
Ankle Foot Orthosis ◽  
Normal Knee ◽  
Actuation System ◽  
Foot Orthosis

A knee-ankle-foot orthosis (KAFO) spans the knee, ankle and foot, and assists in the walking motion of those who suffer neuromuscular deficiencies. KAFOs can be classified as passive, semi-dynamic and dynamic. Passive KAFOs lock the knee joint during the whole gait cycle. Semi dynamic KAFOs lock the knee joint during the stance phase. Dynamic KAFOs attempt to reproduce normal knee motions during the whole gait cycle. Two types of dynamic KAFOs have been reported in the literature. The first one is activated by using a pneumatic system, and the second one uses a spring mechanism. Both systems are bulky and controlled through complex control systems that limit their application as assistive devices. The purpose of our research is to develop a dynamic KAFO that is actuated easily by employing shape memory materials. Such an actuation system makes the KAFO lightweight and with a great commercialization potential. The purpose of this paper is to present a conceptual design for the knee actuator of a dynamic KAFO. This actuator uses torsional shape memory rods to match the stiffness of the knee joint of the KAFO with that of a normal knee joint during the walking gait cycle. Joint stiffness is measured by the moment around the joint per degree of joint rotation. The proposed actuator includes two parts that work independently during the two phases of the gait cycle. The first part engages only during the stance phase and the other works only during the swing phase. Each part is developed by combining a superelastic (SE) rod and a rotary spring in series. The conceptual design is verified by simulation. The simulation results show that the proposed knee actuator reproduces the stiffness of the normal knee joint during the whole gait cycle. It is thus possible to develop a novel dynamic KAFO that can provide normal knee stiffness characteristics to assist individuals with quadriceps deficiency.

scholarly journals The Effectiveness of Functional Electrical Stimulation Based on a Normal Gait Pattern on Subjects with Early Stroke: A Randomized Controlled Trial

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Zhimei Tan ◽  
Huihua Liu ◽  
Tiebin Yan ◽  
Dongmei Jin ◽  
Xiaokuo He ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Placebo Group ◽  
Controlled Trial ◽  
Berg Balance Scale ◽  
Gait Pattern ◽  
Walking Ability ◽  
Dual Channel ◽  
Normal Gait ◽  
Postural Assessment ◽  
And Performance

Objective.To investigate the effectiveness of four-channel FES based on a normal gait pattern on improving functional ability in subjects early after ischemic stroke.Methods.Forty-five subjects were randomly assigned into a four-channel FES group (n=16), a placebo group (n=15), or a dual-channel group (n=14). Stimulation lasted for 30 min in each session with 1 session/day, 5 days a week for 3 weeks. All subjects were assessed at baseline, at 3 weeks of treatment, and at 3 months after the treatment had finished. The assessments included Fugl-Meyer Assessment (FMA), the Postural Assessment Scale for Stroke Patients (PASS), Berg Balance Scale (BBS), Functional Ambulation Category (FAC), and the Modified Barthel Index (MBI).Results.All 3 groups demonstrated significant improvements in all outcome measurements from pre- to posttreatment and further gains at followup. The score of FMA and MBI improved significantly in the four-channel group at the end of the 3 weeks of training. And the scores of PASS, BBS, MBI, and FAC in the four-channel group were significantly higher than those of the placebo group.Conclusions.This study indicated that four-channel FES can improve motor function, balance, walking ability, and performance of activities of daily living in subjects with early ischemic stroke.

Functional assessment of outcome of surgery to correct patellofemoral instability in human patients

2020 ◽  
Vol 16 (3) ◽  
pp. 161-167
Author(s):  
D.A. Clark ◽  
D.L. Simpson ◽  
J.D. Eldridge ◽  
V. Pai ◽  
G.R. Colborne
Keyword(s):  
Knee Joint ◽  
Gait Analysis ◽  
Patellar Instability ◽  
Weight Bearing ◽  
Patellofemoral Instability ◽  
Knee Extensor ◽  
Gait Pattern ◽  
Joint Moments ◽  
Normal Gait ◽  
Gait Function

A case-control study with 6 months of patient follow up. This study sought to determine if surgery followed by rehabilitation for patellar instability could restore normal gait function. A previous study has established abnormalities in gait pattern and joint congruence in patients with a history of patellar instability. We hypothesised that surgery for patellofemoral instability would improve knee function. Eight human patients (mean age 29, range 17-42) who were awaiting patella stabilisation surgery (5 tibial tuberosity osteotomy, 2 medial patellofemoral ligament reconstruction, 1 trochleoplasty) were compared against eight normal Controls (mean age 28, range 19-31). Patients were assessed pre-operatively and six months after surgery by biomechanical gait analysis. Gait trials involved simultaneous collection of kinematic and force data. Patients were grouped into two subgroups pre-operatively based on knee joint net moment during stance, and their joint moments during stance pre- and post-operatively were compared against the Control subjects. In pre-operative gait analysis, four patients (P1) produced some extensor moment in early stance and four (P2) demonstrated a severe gait deficiency with failure to generate a knee extensor moment during stance. Normalisation in gait pattern was observed in all patients post-operatively. Those who had the most severe gait abnormality (P2) demonstrated the most improvement in their knee joint moments. Improvements were observed in the milder (P1) cases, but these were less dramatic. Patella stabilisation by surgery can restore normal gait function. Normalising the anatomy of the knee extensor mechanism is the objective of surgery. Normal anatomy facilitates the rehabilitation objectives of optimising extensor function during the weight-bearing phase of gait.

scholarly journals Analysis and characterization of the normal gait phases of walking Warmblood horses as a tool for the diagnosis of lameness

2018 ◽  
Vol 38 (3) ◽  
pp. 536-543 ◽  
Author(s):  
Lázaro Morales-Acosta ◽  
Armando Ortiz-Prado ◽  
Víctor H. Jacobo-Armendáriz ◽  
Raide A. González-Carbonell
Keyword(s):  
Hind Limb ◽  
Gait Cycle ◽  
Experimental Methods ◽  
Gait Pattern ◽  
Diagnostic Techniques ◽  
Maximum Displacement ◽  
Orthogonal Acceleration ◽  
Normal Gait

ABSTRACT: Horses with lameness modify gait behavior, but when it is subtle, it may not be possible to identify it clinically. The objective of this research is to characterize the normal gait phases of walking Warmblood horses by combining photogrammetry and accelerometry to monitor lameness to indicate a structural or functional disorder in the extremities. The study was conducted in 23 adult male Warmblood horses. Photogrammetry was used to identify the kinematic variables of the limbs and the markers path over time; triaxial accelerometers were used to capture the orthogonal acceleration components. It was determined that only 10 horses showed a normal gait pattern, there was a 43% correspondence between the expert´s judgment and the diagnostic techniques. According to the Stashak classification of the gait phases, cycle phases to forelimb were 34/4/8/13/41, while for hind limb were 54/11/8/8/19 (% of the stride). The range of motion (ROM) of the neck, knee and fetlock joints was 45.52±5.63°, 196.04±19.7° and 209±11.52° respectively. A combination of experimental methods was used to identify the phases of gait cycle of healthy horses. There was a correspondence in the location of the points of maximum displacement of the limbs with both techniques. More detailed information on the limbs movement was obtained using the accelerometer technology. These methods are applicable to other conditions either outdoors or in the lab.

A Biomechanical Analysis of Amputee Athlete Gait

1990 ◽  
Vol 6 (3) ◽  
pp. 262-282 ◽  
Author(s):  
Andrew W. Smith
Keyword(s):  
Knee Joint ◽  
Gait Cycle ◽  
Biomechanical Analysis ◽  
Kinematic Data ◽  
Joint Kinetics ◽  
Additional Information ◽  
Prosthetic Limb ◽  
Normal Gait ◽  
Coefficients Of Variation ◽  
Knee Flexors

The aims of the present study were to quantify lower limb kinetics and kinematics during walking and slow jogging of below-knee amputee athletes and to demonstrate the usefulness of the additional information provided by kinetic analyses as compared to that of kinematic assessments alone. Kinematic and force platform data from three amputee subjects were collected while the subjects walked and jogged in the laboratory. Results indicated that neither prosthesis (SACH and an energy-storing carbon fiber or ESCF) emulated the kinetics or the kinematics of so-called normal gait during walking. While the knee joint on the prosthetic side clearly tended to be biased toward extension during stance, the knee flexors were dominant and acted concentrically during this phase of the gait cycle. An examination of prosthetic limb hip and knee joint kinetics at both cadences revealed the functional role played by the hamstrings early in stance. The results indicated that with increasing cadence, less variability, measured by coefficients of variation, was evident in the kinematic data while the opposite was true for the kinetics.

scholarly journals Real-Time Identification of Knee Joint Walking Gait as Preliminary Signal for Developing Lower Limb Exoskeleton

Electronics ◽  
2021 ◽  
Vol 10 (17) ◽  
pp. 2117
Author(s):  
Susanto Susanto ◽  
Ipensius Tua Simorangkir ◽  
Riska Analia ◽  
Daniel Sutopo Pamungkas ◽  
Hendawan Soebhakti ◽  
...  
Keyword(s):  
Knee Joint ◽  
Real Time ◽  
Gait Cycle ◽  
Initial Step ◽  
Knee Joints ◽  
Walking Gait ◽  
Lower Limb Exoskeleton ◽  
Walking Rehabilitation ◽  
Research Experiment ◽  
Real Time Identification

An exoskeleton is a device used for walking rehabilitation. In order to develop a proper rehabilitation exoskeleton, a user’s walking intention needs to be captured as the initial step of work. Moreover, every human has a unique walking gait style. This work introduced a wearable sensor, which aimed to recognize the walking gait phase, as the fundamental step before applying it into the rehabilitation exoskeleton. The sensor used in this work was the IMU sensor, used to recognize the pitch angle generated from the knee joint while the user walks, as information about the walking gait cycle, before doing the investigation on how to identify the walking gait cycle. In order to identify the walking gait cycle, Neural Network has been proposed as a method. The gait cycle identification was generated to recognize the gait cycle on the knee joint. To verify the performance of the proposed method, experiments have been done in real-time application. The experiments were carried out with different processes such as walking on a flat floor, climbing up, and walking down stairs. Five subjects were trained and tested using the system. The experiments showed that the proposed method was able to recognize each gait cycle for all users as they wore the sensor on their knee joints. This study has the potential to be applied on an exoskeleton rehabilitation robot as a further research experiment.

Design of a 6-DOF Robotic Gait Training System With Closed-Chain Foot Initiated Kinematics Control

2015 ◽  
Author(s):  
Wei Liu ◽  
John Kovaleski ◽  
Marcus Hollis
Keyword(s):  
Three Dimensional ◽  
Computer Software ◽  
Gait Training ◽  
Gait Pattern ◽  
Training System ◽  
Normal Walking ◽  
Robot Assisted ◽  
Walking Gait ◽  
The Right ◽  
Joint Motions

Robotic assisted rehabilitation, taking advantage of neuroplasticity, has been shown to be helpful in regaining some degree of gait performance. Robot-applied movement along with voluntary efferent motor commands coordinated with the robot allows optimization of motion training. We present the design and characteristics of a novel foot-based 6-degree-of-freedom (DOF) robot-assisted gait training system where the limb trajectory mirrored the normal walking gait. The goal of this study was to compare robot-assisted gait to normal walking gait, where the limb moved independently without robotics. Motion analysis was used to record the three-dimensional kinematics of the right lower extremity. Walking motion data were determined and transferred to the robotic motion application software for inclusion in the robotic trials where the robot computer software was programmed to produce a gait pattern in the foot equivalent to the gait pattern recorded from the normal walking gait trial. Results demonstrated that ankle; knee and hip joint motions produced by the robot are consistent with the joint motions in walking gait. We believe that this control algorithm provides a rationale for use in future rehabilitation, targeting robot-assisted training in people with neuromuscular disabilities such as stroke.

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