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Evaluation of Trunk Movement System Strategies through the Concept of Muscle Synergies

Bagheri Rouchi, Mahdi | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44427 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Firoozbakhsh, Keikhosrow; Parnianpour, Mohammad
  7. Abstract:
  8. In this study, by dividing spine motion in two part, ordinary movement and initial-final accelerated movement, the commands of CNS are evaluated by optimization methods to find synchronous and time varying synergies. Spine, which is a complex structure of vertebrae and cartilage, has been modeled by a 3D inverted pendulum with a ball and socket joint at L4/L5 incorporated with 18 muscle fascicles. Planning of point-to-point spine motion is performed by optimal control method in combined with cost function of kinematics and kinetic features that available in spine structure. In the second step, coactivation of muscles is predicted by utilizing static optimization along with stability constraint. In the viewpoint of equilibrium point hypothesis, stability of spine during its motion can be seen as selecting muscle parameters to shape a particular potential energy function suitable for a 3D motion of spine. In the next step to investigate the CNS's orders in spine motion, specified 8 goals corresponded to the maximum range of motion in 3D spine's movement, we use of 3 level of reaching velocity to goal to make set of motion. By dividing the muscle activation in two parts, phasic and tonic, then, time varying muscle synergies are obtained. Results are shown that by 4 pairs of phasic and tonic synergies we can express CNS behavior to control of spine motion in various goals and velocities. The stability condition have no sensitive effect on this synergies, also at the initial and final state of movement, there are 4 initial synchronous muscle synergies that can be caused by stability condition and 6 synergies at the final state
  9. Keywords:
  10. Spine ; Optimal Control ; Time Varying Synergy ; Lumbar Spine Portion

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