Above-knee Prosthesis Research Articles

309 歩行動作実験に基づく歩容解析(OS6-2 運動解析)(OS6 スポーツと医療福祉工学)

In this study, the relationship between instructed conditions of gait and the change of joint angles of a leg was experimentally examined. The results of this study will be useful for the development of an above-knee prosthesis that can adjust to various walking motion. It was clarified that the change of stride and pace in walking motion shows different tendency according to the instructed condition in the experiment.

力学モデルによる大腿義足の関節粘弾性調整法

力学モデルによる大腿義足の関節粘弾性調整法

310 パッシブ制御膝継ぎ手を有する大腿義足の解析的検討(OS6-2 運動解析)(OS6 スポーツと医療福祉工学)

Most of above-knee prostheses have link mechanism at knee joint for comfortable walking. Recently Intelligent prosthesis that can automatically adjust to the change of gait has appeared However, there is no prosthesis that can adjust to various motions. The purpose of this study is the development of an above-knee prosthesis that can adjust to various walking gaits by simple mechanism and control. In this report, joint torque in various walking and control mechanism of the knee joint were analytically examined.

Mechatronic Integration in Exoprosthetics

The basic requirements for artificial limbs are the replacement of body functions in respect to the skeletal system for supporting loads as well restoration of human movement. This leads to typical mechatronical concepts. As an example a myo-electric arm prosthesis with integrated grasp stabilization is described. This system also serves as a Manipulator for a mobile care robot. As a second example an electronically controlled above-knee prosthesis is described. It is shown that complex functions, reduced space availability and safety relevance inhibit frequently the use of standard components or OEM parts for exoprosthetics. The system requirements lead to integrated mechatronic solutions.

Adjusting technique of knee mechanism of above-knee prosthesis for preventing knee-collapse

Adjusting technique of knee mechanism of above-knee prosthesis for preventing knee-collapse

Influence of Knee Joints of Transfemoral Prosthesis on Walking Energy Consumption.

With the primary objective of examining a useful index for appropriate knee joints of above-knee prosthesis, the effect on the human body was studied by measuring walking velocity (m/s), stride length (m), and walking. Subjects consisted of 4 above-knee amputees, and the measurement was conducted using a three-dimensional co-ordinate recorder and a gait analysis system of a force plate. The results suggest that the effect of knee joints can be evaluated by walking energy consumption per unit gait distance.

Identification of pressure distribution at the socket interface of an above-knee prosthesis

The purpose of this study is to propose an indirect approach to identifying the pressure distribution at the stump-socket interface of a prosthesis. A finite-element model of the socket is combined with the observed deformation at the outer surface of the experimental socket, and the pressure identification problem is formulated in the context of an inverse problem. Under the criterion of the minimization of elastic energy, the most plausible pressure at the interface is searched based on the observed socket deformation. The proposed procedure is implemented by using a commercially available finite-element package, and successfully used for the quadrilateral socket of an above-knee prosthesis.

Feedback Error Learning Neural Network for Above-Knee Prosthesis

The purpose of this paper is to show how Feedback Error Learning can be applied to control hip and knee joints in an active Above-Knee Prosthesis. Feedback Error Learning is a control scheme based on neural networks and has its origin in physiological studies. A total energy method is used, thus eliminating the need for a known mathematical model of the prosthesis. The system's total energy is extracted from kinematic analysis, and used as an equivalent mathematical model. The findings conclusively show Feedback Error Learning is a suitable control strategy for an active above-knee prosthesis.

The impact of knee joint flexion on infrainguinal vascular grafts: An angiographic study

To characterise the morphologic behaviour of infrainguinal vascular grafts during flexion of the knee. A prospective angiographic study. In 64 infrainguinal bypass grafts, intravenous digital subtraction angiography was performed within the first postoperative week. Frontal and lateral projection angiograms with the knee joint extended and with a 80-90 degrees flexion were taken. The distal anastomosis of the bypass was performed below-knee in 49 cases (18 in situ veins, 8 reversed veins with an anatomic course, 2 reversed veins with an extra-anatomic course, 4 composite grafts, 15 synthetic grafts with an anatomic course (14 polytetrafluoroethylene (ePTFE), 1 polyurethane), and two synthetic grafts with an extra-anatomic course. Fifteen ePTFE prostheses were implanted in the above-knee position. Out of 64 cases a total of 16 grafts showed stenotic kinking during flexion: two of the 18 in situ vein grafts, four of the 12 reversed vein grafts implanted with an anatomic course, one of the two reversed vein grafts implanted in an extra-anatomic site, eight of the 15 synthetic grafts crossing the knee, 0 of the two extra-anatomic ePTFE grafts, and one of the 15 cases of above-knee femoropopliteal ePTFE grafts. Stenotic kinking due to knee flexion can affect all kinds of bypass grafts including vein grafts placed anatomically and above-knee prostheses.

Relationship between the mechanical properties of knee joints of above-knee prostheses and amputee gait

Complex pathologies associated with chronic health conditions must be dealt in a coordinated way and the ‘multidisciplinary team’ approach (MDTA) represents the most efficacious way of managing these patients. Over the last 25 years, the initial limited field for joint interventions by several specialists has been progressively expanded and this article reviews some of the conditions in which the MDTA has found useful application.This has been the case in fields as diverse as primary healthcare, oncology, diabetes, cardiovascular, chronic kidney diseases and high-risk pregnancy. In the latter situation, an MDTA can offer clear advantages for pregnancies in solid organ recipient women. In these patients, a close collaboration is mandatory between a series of dedicated physicians (including, but not limited to, infertility and maternal–foetal medicine specialists, obstetricians, paediatricians, transplant physicians, geneticists and psychologists). Such a team should be active before, during and after pregnancy and should cope with all their reproductive health needs.

Optimal control for an above-knee prosthesis with two degrees of freedom

Our previous research and clinical tests of a self-contained powered above-knee prosthesis (AKP) showed that a knee joint with one degree of freedom (DOF) increases the energy cost of walking with respect to able-bodied subjects. Better symmetry of the gait can improve performance, so we suggest here the integration of a second powered DOF into the knee joint mechanism to control the internal-external rotation of the shank-foot complex. The control for the AKP with two DOFs is based on a method of optimal tracking. The data used for analysis were collected in able-bodied subjects braced with an ankle splint to experimentally duplicate a gait like that of amputees using a two-DOF prosthesis. The simulation showed the following: (1) the technique of optimal programming can be used for simulation of the artificial leg during locomotion; (2) the optimal tracking method is an efficient tool for selection of actuators for the above-knee prosthesis, ensuring that the tracking remains within limits. Limitation of joint torque is desirable in order to reduce the size of the motor, but beyond a certain point limiting maximal torques lead to tracking errors that are associated with higher energy costs and hence the need for a larger power source. The errors are also associated with higher forces at the interface between the socket and the prosthesis. The optimal tracking method allows the optimization of tracking with constraints on the size of the motor used and its energy cost.

Optimal control for an above-knee prosthesis with two degrees of freedom

Our previous research and clinical tests of a self-contained powered above-knee prosthesis (AKP) showed that a knee joint with one degree of freedom (DOF) increases the energy cost of walking with respect to able-bodied subjects. Better symmetry of the gait can improve performance, so we suggest here the integration of a second powered DOF into the knee joint mechanism to control the internal-external rotation of the shank-foot complex. The control for the AKP with two DOFs is based on a method of optimal tracking. The data used for analysis were collected in able-bodied subjects braced with an ankle splint to experimentally duplicate a gait like that of amputees using a two-DOF prosthesis. The simulation showed the following: (1) the technique of optimal programming can be used for simulation of the artificial leg during locomotion; (2) the optimal tracking method is an efficient tool for selection of actuators for the above-knee prosthesis, ensuring that the tracking remains within limits. Limitation of joint torque is desirable in order to reduce the size of the motor, but beyond a certain point limiting maximal torques lead to tracking errors that are associated with higher energy costs and hence the need for a larger power source. The errors are also associated with higher forces at the interface between the socket and the prosthesis. The optimal tracking method allows the optimization of tracking with constraints on the size of the motor used and its energy cost.

Fuzzy Control of Electrohydraulic Above-Knee Prostheses

A fuzzy controller is employed to control an electrohydraulic four-bar above-knee prosthesis for the swing phase in level walking. A two-dimensional (sagittal plane)mechanical model of the above-knee amputee is developed and the amputee prosthesis system is simulated for the swing phase. The man-machine system has two fuzzy controllers : a knee fuzzy controller which adjusts the knee damping moment so the prosthetic knee angle trajectory will track that of the patient's sound knee in the previous swing and a hip fuzzy controller utilized to model the way that an amputee will manipulate the prosthesis. From an optimal design procedure, a set of fuzzy controllers is found and an optimal relationship between variations of initial stump velocity and initial artificial shank velocity for the amputee is found. The results showed that the amputee swing gait can be controlled to a near normal one and walking with varied speed is possible.

Output space tracking control for above-knee prosthesis.

The control of a knee joint in an active above-knee prosthesis has been designed using the Lyapunov tracking method. A simulation of locomotion was done to prove that the tracking control in output space is a valuable real time control method for artificial legs. The data used for simulation was collected in able-bodied subjects while they walked on a powered treadmill. Human volunteers were braced with an ankle splint (limiting dorsi- and plantar flexion) and with a knee cage (limiting knee movements to the lateral plane). We studied the achieved tracking of the prescribed knee motion, deviations of the thigh movement from the prescribed trajectory, maximal angular deviations from the desired trajectory and the power consumption as functions of a limited maximal knee torque and a damping constant in the knee actuator. We found that the use of output tracking method is suitable for the design of appropriate hardware of an above-knee prosthesis and for real-time control.

Development of Electrohydraulic Controlled Above-Knee Prostheses

In this study, a four-bar linkage above-knee (AK) prosthesis with an electrohydraulic controller was developed. A microcomputer was employed to regulate the puppet valve of the hydraulic control system. To obtain a reliable design, a test rig was also designed for evaluation of the knee controller performance. The rig had a variable-speed alternate-current servomotor for simulating the angular displacement of the hip joint at different walking speeds. A proportional+derivative (PD) controller was employed to regulate the knee torque of the above-knee prosthesis. Experimental results revealed that the controller can produce a knee joint trajectory close to that of a normal person or a designed one. Use of the electrohydraulic controller can be expected to improve the amputee swing phase gait.

Analysis of Axial Force and Moment on Above-Knee Prosthesis Socket -Application of Control Signal to A/K Prosthesis-

Analysis of Axial Force and Moment on Above-Knee Prosthesis Socket -Application of Control Signal to A/K Prosthesis-

Mathematical modelling and field trials of an inexpensive endoskeletal above-knee prosthesis.

The swing-phase motion of the shank of an above-knee prosthesis has been modelled mathematically. An inexpensive endoskeletal prosthesis was designed using the Jaipur foot and conduit pipes with a hinge joint for the knee. Results of field trials and the modelling indicate that a very simple above-knee prosthesis can give near normal gait at "normal" walking speeds on flat surfaces. The swing of the shank is most sensitive to the timing of toe-off.

Adaptative control of above knee electro-hydraulic prosthesis.

Conventional designs of an above-knee prosthesis are based on mechanisms with mechanical properties (such as friction, spring and damping coefficients) that remain constant during changing cadence. These designs are unable to replace natural legs due to the lack of active knee joint control. Since the nonlinear and time-varying dynamic coupling between the thigh and the prosthetic limb is high during swing phase, an adaptive control is employed to control the knee joint motion. Two dimensional simulation indicates that the adaptive controller can improve the appearance of gait pattern. It is adaptable to walking speed and can compensate for the variations of hip moment, hip trajectory and toe-off conditions.

Development of an above-knee prosthesis equipped with a microcomputer-controlled knee joint: first test results

The shortcomings of conventional above-knee prostheses are due to their lack of adaptive control. Implementation of a microcomputer controlling the knee joint in a passive way has been suggested to enhance the patient's gait comfort, safety and cosmesis. This approach was used in the design of a new prosthetic system for the above-knee amputee, and tested on one patient. The knee joint of a conventional, modular prosthesis was replaced by a knee joint mechanism, equipped with a controllable brake on the knee joint axis. Sensors and a microcomputer were added, keeping the system self-contained. The modularity of the design permits the use of an alternative, external, PC-based control unit, emulating the self-contained one, and offering extended data monitoring and storage facilities. For both units an operating environment was written, including sensor/actuator interfacing and the implementation of a real-time interrupt, executing the control algorithm. A double finite state approach was used in the design of the control algorithm. On a higher level, the mode identification algorithm reveals the patient's intent. Within a specific mode (lower level), the relevant mode control algorithm looks for the current phase within the gait cycle. Within a particular phase, a specific simple control action with the brake replaces normal knee muscle activity. Test were carried out with one prosthetic patient using a basic control algorithm for level walking, allowing controlled knee flexion during stance phase. The technical feasibility of such a concept is illustrated by the test results, even though only flexion during early stance phase was controlled during the trials. Patient acceptance is not straightforward since knee flexion during stance phase is associated with knee buckling.

Control aspects of active above-knee prosthesis

A methodology for control of an active above-knee prosthesis (AKP) is described. This approach is called Artificial Reflex Control (ARC), and depends on the use of production rules, so that the controller may be thought of as a leg movement expert. This control strategy is applicable to a variety of different gait modes. Automatic adaptation, according to the environment, and to the gait mode required, is based on heuristics related to human motor control.