| 1. |
- Berbyuk, Viktor, 1953
(författare)
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Dynamic simulation of a human gait and design problems of the lower limb prostheses
- 1999
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Ingår i: Proceedings of the 12th International Biomechanics Seminar, Ed. C. Högfors, Chalmers, Gothenburg, Sweden, September 10-11, 1999. - 1100-2247. ; XII, s. 1-20
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Konferensbidrag (refereegranskat)abstract
- In this paper the methodology and the numerical algorithm are proposed such as suitable both for the dynamic simulation of a human gait and for solving of the design problems of the lower limb prostheses. The methodology is based on the combination of the optimal control theory and the mathematical modeling with broad utilization of the data obtained from the biomechanical experiments. A special procedure is used for converting the initial optimal control problems for the highly nonlinear and complex bipedal locomotion system into the standard nonlinear programming problems. It is made by approximation of the independent variable functions using the combination of a spline and the Fourier series and the solution of the semi-inverse dynamics problem. The key feature of the algorithm proposed is its high numerical effectiveness and the possibility to satisfy many restrictions imposed on the phase coordinates of the system automatically and accurately. The proposed methodology is illustrated by the computer simulation of a human gait and the numerical results of solution of the design problems of the energy-optimal above-knee prostheses with several types of the structure of the knee mechanisms.
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| 2. |
- Berbyuk, Viktor, 1953
(författare)
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Energy-optimal control of human leg in swing phase
- 1995
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Ingår i: Biomechanics Seminar. - 1100-2247. ; 9, s. 32-49
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Konferensbidrag (refereegranskat)abstract
- The mathematical model and efficient algorithm for designing the energy-optimal controlled processes of a human leg in the swing phase are proposed. This algorithm is based on special conversion of the optimal control problem for nonlinear dynamical system modeled a human leg into a standard nonlinear programming problem. The objective function for the optimization algorithm is the integral over swing phase's time from the sum of the mechanical power absolute values for all controlling stimuli. A number of the energy-optimal controlled processes of a human leg under different boundary conditions and restrictions on phase coordinates have been obtained. The kinematical and dynamical characteristics of obtained optimal controlled processes are compared with respective characteristics of a human leg's swing phase during normal gait.
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| 3. |
- Berbyuk, Viktor, 1953, et al.
(författare)
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Internal torques of human upper extremity during its optimal motion in vertical plane
- 1997
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Ingår i: The Tenth Biomechanics Seminar. - 1100-2247. ; 10, s. 66-83
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Konferensbidrag (refereegranskat)abstract
- In the paper a number of optimal control problems for the motion of the human upper extremity (HUE), for different types of working tasks, are considered. The performance index used in these problems is the integral over the duration of the working task of the sum of the square of the controlling stimuli acting at the joints of the human arm. Under some conditions this performance index can be used for evaluation of the muscles' energy expenditure during human movements. The HUE is simulated by a plane multibody system of rigid masses. The system comprises the three elements with mass and rotatory inertia modelled the upper arm, the forearm and the hand. The controlled motions of the mechanical system are described in terms of joint angles and Cartesian coordinates of the shoulder joint, through the application of Lagrange's equations. The main aim of the study is an investigation of the interaction between the gravity forces and the internal torques acting at the joints during goal-directed extremal motions of the HUE. The analysis of the internal torques, energetic and viscoelastic characteristics of the shoulder, the elbow and the wrist joints for the exstremal controlled motions of the human arm under the external load acting on the hand has been done.
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| 4. |
- Berbyuk, Viktor, 1953, et al.
(författare)
-
Modeling of human locomotion with artificial lower extremities
- 1994
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Ingår i: Biomechanics Seminar. - 1100-2247. ; 8, s. 167-178
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Konferensbidrag (refereegranskat)abstract
- To solve the problems of improvement of the existent and creation of new efficient lower limb prostheses, and to study effect of prosthesis design, as a special technical device, on kinematical dynamical energetical and other characteristics of amputee locomotion it is expedient to use wide capabilities of mathematical modelling of a human walk process on a prosthetic limb. There was proposed earlier mathematical models of biped walk having different degrees of adequacy in multitude of works. These models were used for different purposes: investigation of kinematical dynamical and energetical characteristics of human gait, working out and creation of antropomorphic walking machines, etc. In the given paper a mathematical model has been proposed for investigation of dynamics of an amputee's locomotor system with a below-knee prosthesis. Based on this model computer program has been composed. The series of problems of dynamics of a two-leggal walking, calculation of consumption of energy on motion and optimization of elastic parameters of the prosthetic foot design have been solved.
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| 5. |
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