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Dynamic Modeling and Control of a Robotic Prosthetic Foot for Transfemoral Amputation

Heidarzadeh Khoramabadi, Siamak | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49354 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Salarieh, Hassan; Alasty, Aria
  7. Abstract:
  8. The present research has dealt with the modeling and control of a robotic prosthetic foot for transfemoral amputees. In the beginning of this research, we have modeled the normal gait. In order to accomplish this modeling, we have chosen a 7-body segment skeletal model of the human body and derived the motion equations using Lagrangian equations. Then, we have developed a smooth contact model for the ground. After controlling normal gait, we have attempted to model and control the ankle and knee prosthesis. We assumed a rigid model for the ankle prosthesis and derived its dynamic equations. Then, we developed a robust model reference adaptive impedance control (RMRAIC) scheme based on the Lyapunov stability analysis. The impedance model considered is a nonlinear second order stable ODE whose inputs are the reference trajectory for the ankle and the interaction moments about the ankle caused by ground reaction forces (GRFs). The controller is designed to track the trajectory generated by the impedance model dynamics. Moreover, from the viewpoint of Lyapunov stability analysis, the estimations in the control law will all remain bounded. After designing this controller, we have introduced an algorithm dictating the reference trajectory independent of time. Then, inspiring from the literature, we introduced a mechanism for the ankle. The mechanism is consisted of an electric motor in series with a transmission. Also, there exist an appropriate linear spring in the mechanism intended to bear the body weight in the late stance phase. After controlling the ankle prosthesis we further attempted to model and control a prosthetic knee. In the route to the end of this research and the same as the procedure presented, we firstly modeled the knee prosthesis and developed a controller the same as the controller for the ankle prosthesis. Then, in order to make the reference trajectory of knee independent of time, we assumed an artificial interaction moment about the knee prosthesis, and added this effect to interaction moments caused by the amputee and the ground. Considering all this interactions, we hypothesized that selecting the current knee trajectory as the reference trajectory will result in a flexible, appropriate and human-like knee movement. Finally we have introduced a mechanism for the knee prosthesis and derived the relationship between the knee torque and the torque required by the motor in the mechanism. Simulation results have shown the effectiveness of control algorithms for the both of ankle and knee prostheses
  9. Keywords:
  10. Dynamic Modeling ; Robust Control ; Adaptive Control ; Impedance Control ; Knee Prosthesis ; Ankle Modeling ; Above Knee Prosthesis

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