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Title: Musculo-skeletal modelling and parameterisation in vivo
Author: Yu, Tung Fai
ISNI:       0000 0004 5360 8845
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2014
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This thesis describes the development of an anatomically meaningful musculo-skeletal model of the human arm, incorporating two modified Hill muscle models representing the elbow flexor and extensor muscles. In vivo experimental methods to determine parameter values are presented. The stimulus for this work was to enable the prediction of movement, to support development of prostheses and orthoses such as Functional Electrical Stimulation (FES). A key problem in model based movement studies is that the passive parameter values in the Hill muscle models and the joint had not been experimentally determined in vivo. The result has been an inability for predictive models to generate realistic predictions of human movement dynamics. In the model, movement dynamics of the forearm was described using the Newton-Euler method, which was validated from analysis of physical pendulum. Structural identifiability analyses of the muscle models ensured that values for the model parameters could be uniquely determined from perfect noise free data. A novel experimental procedure termed the passive movement method is described, which exclusively parameterised the model’s passive components. Simulated model dynamics were fitted to measured movements of the freely swinging forearm under gravity. Model values were obtained on an individual subject basis. The average muscle model spring and damping constants for four healthy subjects were 143N/m and 1.73Ns/m respectively. Separately, the force/length characteristics of the muscles’ active component, the contractile element (CE), were obtained from measurements of isometric maximum voluntary contraction (MVC) at different elbow angles. The results for the five healthy subjects showed good agreement with results reported in the literature. A preliminary experiment was performed to predict elbow flexion movement under FES. An electrical stimulus that generated a specified isometric elbow flexion moment (10% of MVC) was applied to generate elbow flexion movement. Simulated FES arm movement was compared with the measured results. The simulated change in elbow angle did not agree with the measured data. A major cause for this was believed to be skin movement causing a change in the current path across the muscle fibres, thus affecting the force generated. The passive movement method described in this thesis filled an important chapter to fully parameterise musculo-skeletal models in vivo. Although in the FES movement experiment, simulated change in elbow angle generated by FES did not agree with measured data, the shape of the dynamic response in the fitted simulated movement showed good agreement with the measured FES movement.
Supervisor: Not available Sponsor: Engineering and Physical Sciences Research Council (EPSRC)
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QH301 Biology ; QP Physiology ; TA Engineering (General). Civil engineering (General)