Wyniki wyszukiwania - BazTech

1

A 4-link model of a human for simulating a forward fall

Grzelczyk D., Biesiacki P., Mrozowski J., Awrejcewicz J.

Vibrations in Physical Systems

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2018

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Vol. 29

art. no. 2018008

EN

In this paper we consider a 4-link model of a human for simulating a forward fall. The model implemented in Mathematica is constructed based on a planar mechanical system with a non-linear impact law modelling the wrist-ground contact. The segments of the human body are modelled as bodies connected by rotary elements which correspond to the human joints. Parameters and kinematic relations used in numerical analysis are obtained based on the 3D scanned model of the human body created in Inventor and experimental observation by the motion capture system. Validation of the model is conducted by means of comparing the simulation of the impact force with the experimental data obtained from the force platform. The obtained ground reaction forces can be useful for the finite element analysis of the numerical model of the human upper extremity.

2

Planar arm movement trajectory formation: an optimization based simulation study

Zadravec M., Matjačić Z.

Biocybernetics and Biomedical Engineering

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2013

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Vol. 33, no. 2

106--117

EN

Rehabilitation of post stroke patients with upper extremity motor deficits is typically focused on relearning of motor abilities and functionalities requiring interaction with physiotherapists and/or rehabilitation robots. In a point-to-point movement training, the trajectories are usually arbitrarily determined without considering the motor impairment of the individual. In this paper, we used an optimal control model based on arm dynamics enabling also incorporation of muscle functioning constraints (i.e. simulation of muscle tightness) to find the optimal trajectories for planar arm reaching movements. First, we tested ability of the minimum joint torque cost function to replicate the trajectories obtained in previously published experimental trials done by neurologically intact subjects, and second, we predicted the optimal trajectories when muscle constraints were modeled. The resulting optimal trajectories show considerable similarity as compared to the experimental data, while on the other hand, the muscle constraints play a major role in determination of the optimal trajectories for stroke rehabilitation.

3

Influence of upper extremity position on EMG signal measures calculated in time, frequency and time-frequency domains

Wang J., Bartuzi P., Roman-Liu D.

Acta of Bioengineering and Biomechanics

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2013

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Vol. 15, no. 4

83--91

EN

The aim of this study was to investigate the relationship between time-frequency, time and frequency measures when considering various upper extremity positions below the level of the shoulder and in trapezius as well as deltoideus muscles. During the experiment, 15 subjects performed a task that involved screwing and unscrewing a screw cap on a board in six different locations, i.e., there were six upper extremity positions. Variables were calculated in the time, frequency and time-frequency domains on a recorded EMG signal. The results showed that parameters analyzed in the time-frequency domain were more sensitive to changes in position than parameters analyzed in the frequency domain.

4

Biomechanical Loads and Subjective Stress Exposure to Lumber Graders in Sawmill Industry

Jones T., Kumar S.

International Journal of Occupational Safety and Ergonomics

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2011

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Vol. 17, No. 1

87--97

EN

The aim of this study was to determine biomechanical loads and subjective stresses on lumber graders and associated morbidity in a high risk and repetitive sawmill occupation. The exposures of all 29 male sawmill worker volunteers were recorded. Motion and posture were studied with electrogoniometers, muscle loads were recorded with surface electromyography, and psychophysical stresses were assessed with subjective responses. Fifty-nine percent of the participants reported greater than moderate discomfort in their taskdominant upper extremity. Job performance required an average range of motion of 44º, 21º, and 52º in flexion/extension, radial/ulnar deviations, and pronation/supination respectively. It also required an average of 9% maximum voluntary contraction force and was repeated an average of 34 times/min. This repetitive exertion over an 8-h shift was deemed to be a significant risk factor associated with prevalent upper extremity morbidity.

5

Torque of the operator's upper extremity in relation to its orientation within a normal working space

Hałacz J.

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2010

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nr 13

189-202

EN

This paper presents the results of a study into the effect of some factors determining the orientation of the upper extremity within the normal working space on the torque of the muscles of this extremity. The results of this study may be useful in the anthropotechnical design of controlling devices. The paper also includes data on the torque developed by the upper extremity within the operator's normal working space which are presented in the form of centile characteristics.

PL

W pracy przedstawiono wyniki badań dotyczących wpływu wybranych czynników określających położenie kończyny górnej w normalnej przestrzeni pracy na wartość momentu skręcającego rozwijanego przez mięśnie tej kończyny. Wyniki badań mogą być wykorzystane w antropometrycznym projektowaniu urządzeń sterujących. Przedstawiono także, w formie charakterystyk centylowych, dane dotyczące momentów skręcających rozwijanych przez kończynę górną w normalnej przestrzeni pracy operatora.

6

Computerized Method for Work Space Optimization in Conditions of Static Work

Roman-Liu D., Kędzior K., Rzymkowski C.

International Journal of Occupational Safety and Ergonomics

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1999

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Vol. 5, No. 1

97--108

EN

The aim of this research was to develop a theoretical method for the ergonomic optimization of the work space of the upper limb. This method is based on a model of the upper extremity with 7 degrees of freedom. It consists of 3 rigid elements modeling the arm, forearm, and hand and 34 upper extremity muscles. The trunk is considered immobile. The shoulder joint is modeled as a rotating kinematics pair of third class, the elbow and wrist joints - of fourth class. The minimum sum of muscle force moments in the joints and soft saturation muscle cooperation criterion were used as merit criteria. The developed method makes it possible to effectively solve, in a defined work space, the task of work space optimization.