Passive Knee Joint Mechanism of Transfemoral Prosthesis for Stair Ascent

Analysis of knee kinematics and ground reaction forces (GRFs) is widely used to determine compensatory mechanisms of people with anterior cruciate ligament deficiency (ACLD). However, the practicality of the measurements is subject to their reliability during different trials. This study aims to determine the reliability and repeatability of knee joint rotations and GRFs in people with ACLD during stair ascent. Eight participants with unilateral ACL-deficient knees performed five trials of stair ascent with each leg. The movements were captured by VICON motion analysis system, and GRF components were recorded using force plate. Three-dimensional tibiofemoral joint rotations were calculated. Intraclass correlation coefficient (ICC), standard error of measurement (SEM) and coefficient of multiple correlation (CMC) were calculated ACL-deficient legs showed lower absolute reliability during swing ([Formula: see text]–6.4) than stance phase ([Formula: see text]–2.2) for knee joint rotations. Moderate to high average measure ICCs (0.59–0.98), relative reliability, were achieved for injured and uninjured sides. The results also demonstrated high repeatability for the knee joint rotation ([Formula: see text]–0.97) and GRF ([Formula: see text]–0.99). The outcomes of this study confirmed the consistency and repeatability of the knee joint rotations and GRFs in ACL-deficient subjects. Additionally, ACL-deficient legs exhibited similar levels of reliability and repeatability compared to contralateral legs.

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PROTOTYPE OF TRANSFEMORAL PROSTHESIS WITH AN ACTIVE ARTIFICIAL KNEE

Fundamental and Applied Problems of Engineering and Technology ◽

10.33979/2073-7408-2020-342-4-1-172-180 ◽

2020 ◽

Vol 4 (1) ◽

pp. 172-180

Author(s):

A.M. POLIAKOV ◽

P.K. SOPIN ◽

V.B. LAZAREV ◽

A.I. RYZHKOV ◽

M.A. KOLESOVA ◽

...

Keyword(s):

Mathematical Modeling ◽

Control System ◽

Knee Joint ◽

Hierarchical Control ◽

Control Level ◽

Quality Criteria ◽

Optimal Conditions ◽

Invariant Moments ◽

Biological Similarity ◽

Transfemoral Prosthesis

This article presents a transfemoral prosthesis prototype with active control of an artificial knee joint. One of the main criteria used in the design of the prosthesis was to achieve the maximum biological similarity of this device in order to provide optimal conditions conducive to user natural walking. The artificial knee joint, designed on the basis of a polycentric higed mechanism with intersecting links, provides such conditions at the design level, and a three-level hierarchical control system, built on the basis of an intelligent-synergetic concept, at the control level. To recognize user's intentions, the intelligent subsystem uses algorithms for comparing graphic images of user's walking phases by the method of estimating the invariant moments of Hu. After that, prosthesis elements movements are planned in the synergistic subsystem in accordance with the synergistic quality criteria. The algorithms used in the control system are adjusted depending on what type of artificial foot is used in the prosthesis: active, semi-active or passive (purely mechanical). Mathematical modeling of the prosthesis operation shows that the nature of its functioning corresponds to the quality criteria adopted in the design.

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Myoelectric Torque Control of an Active Transfemoral Prosthesis During Stair Ascent

ASME 2011 Dynamic Systems and Control Conference and Bath/ASME Symposium on Fluid Power and Motion Control, Volume 2 ◽

10.1115/dscc2011-5998 ◽

2011 ◽

Cited By ~ 1

Author(s):

Carl D. Hoover ◽

Kevin B. Fite ◽

George D. Fulk ◽

Donald W. Holmes

Keyword(s):

Impedance Control ◽

Torque Control ◽

Motion Capture Data ◽

Clinical Tests ◽

Joint Kinetics ◽

Set Point ◽

Stair Ascent ◽

Normal Gait ◽

Stiffness And Damping ◽

Transfemoral Prosthesis

This paper presents experimental results of a myoelectric impedance controller designed for reciprocal stair ascent with an active-knee powered transfemoral prosthesis. The controller is modeled from non-amputee (normal) motion capture data, estimating knee torque with a linear two-state (stance/swing) impedance control form that includes proportional myoelectric torque control. The normal gait model is characterized by small stiffness and damping in both stance and swing, a low angle set-point in stance, a high angle set-point in swing, and proportional myoelectric control in stance but not swing. Clinical tests with a single unilateral transfemoral amputee indicate good performance of the controller; however, subject feedback suggests a reduction in the extensive myoelectric torque parameter and the need for constant, balanced myoelectric torque parameters in both stance and swing. Average prosthesis knee joint kinetics from a stairwell test using the amputee-tuned controller compare favorably with non-amputee gait data.

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Multifunctional above-knee prosthesis for stairs' walking

Prosthetics and Orthotics International ◽

10.3109/03093648709078198 ◽

1987 ◽

Vol 11 (3) ◽

pp. 139-145 ◽

Cited By ~ 13

Author(s):

K. Koganezawa ◽

H. Fujimoto ◽

I. Kato

Keyword(s):

Knee Joint ◽

Ankle Joint ◽

Stance Phase ◽

Knee Prosthesis ◽

Power Sources ◽

Stair Ascent ◽

Level Walking ◽

External Power ◽

Leg Prosthesis ◽

Full Body

The multifunctional above-knee prosthesis WLP-7R (Waseda Leg Prosthesis - type 7 Refined) described in this study allows amputees to descend and ascend stairs with no external power sources. With the hydraulic circuit mounted in the shank, the ankle joint and the knee joint mutually conterbalance during stance phase in stair walking as well as level walking so that the following performances are obtained. The yielding (flexing) of the knee joint is prevented and smooth advance from stance-phase to swing-phase is realized in level walking. The gradual yielding of the knee joint and the ankle joint while sustaining full body weight is realized in stair descent. Reciprocal stepping with sound and disabled legs during stair ascent is also realised although the powerful extension of the knee joint during stance phase is not possible. The performance of the WLP-7R was examined by a walking experiment in which amputees could descend and ascend the stairs as well as walk on a flat surface after approximately one hour's training.

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