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Design and Implementation of Variable Impedance Control for Lower-Limb Exoskeletons with Desired Gate Refinement

Asgari, Taha | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52702 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Vossoughi, Gholamreza
  7. Abstract:
  8. The main goal of this thesis is to develop and implement a variable Impedance control method with the ability to refine the desired gait in an online manner. For this purpose, a dataset consisting of 89 healthy gaits was utilized. Then, “Basic shapes” were driven using principal component analysis and their meaningfulness was investigated. Regarding the meaningfulness of coefficients of basic shapes, a normality metric was defined to evaluate the human gaits. Furthermore, as a reference gait refinement in Impedance control, an outer loop was added to change the desired gait, according to traversed gait. Kalman filter was used to estimate the coefficients of basic shapes in this loop. In order to vary Impedance parameters, a variable Impedance controller was used in the inner loop. To ensure the stability of the developed control strategy, besides the current control strategy, a model was simulated to produce human torques. The simulation results showed that the Impedance parameters and reference gait refinement together improve impedance control efficiency. The experiment results conducted on Sharif Exoskeleton demonstrate an approximate 30% decrease in impedance parameters and a 50% decrease in the proposed cost function
  9. Keywords:
  10. Exoskeleton ; Impedance Control ; Principal Component Analysis (PCA) ; Gait Cycle ; Gait Refinement ; Lower Limb Exoskeleton

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