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Modeling and Dynamic Analysis of a Laboratary Prototyped Rotary MR Damper using a Prosthetic Knee

Mousavi, Hamid | 2016

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 48864 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Sayyadi, Hassan
  7. Abstract:
  8. Regaining biomechanical function, comfort and quality of every-day life is a prime consideration when designing prosthetic devices for amputees. The magnetorheological (MR) prosthetic knee, which is the subject of this study, is an example of such a device. The study presents a comprehensive and a combined MR device design and MR fluid design approach, aiming to advance the MR prosthetic knee. First, this study focuses on developing a new configuration on magnetorheological (MR) brake damper as prosthetic knee. The new configuration is a rotary damper using MR fluid with a single rotary disc will act as a brake while MR fluid is activated by magnetic field in different walking gait. The main objective of this study is to investigate a prosthetic knee with one activating rotary disc to accomplish necessary braking torque in walking gait via T-shaped drum with arc surface boundary and implementing of Newton’s equation of motion to derive generated torque at the inner surface of the rotary drum. For this purpose a novel configuration of a T-shaped drum based on the effects of a material deformation process is proposed. In this new design, the T-shaped disc will increase the effective areas of influences in between drum and MR fluid together and the arc wall crushes the particles chains (fibrils) of the MR fluid together instead of breaking them via strain in a conventional MR brake. Second, the design is adjusted as an optimization problem, aiming to maximize the braking torque while off-state torque and the brake’s weight are constrained to be less than certain values. Based on the MR brake applications, minimizing of the off-state torque, the weight of the brake, uniform flux density and low instantaneous electrical power dissipation are under consideration. Third, it is difficult to design a model-based controller, since the MR knee system has nonlinear and very complicated governing mathematical equations. Hence, a hybrid self-organizing fuzzy controller and multidimensional wavelet neural network (HSFCMWNN) is proposed here to control the knee damping coefficient using of the inverse dynamics of the MR rotary damper. To verify the proposed MR brake and control strategy, a prototype of the MR brake with a corresponded test bed is fabricated. The main parts weight of the prototype is 0.446 kg. The weights are desired and has low weight with respect to the previous prosthetic knee brake that are made. The maximum achievable on-state braking torque of the prototype is 38.5 Nm while its off-state braking torque is about 2 Nm. According to the experimental results, the device can be used as an MR prosthetic knee
  9. Keywords:
  10. Biomechanics ; Self Organized Control ; Magnetorheological (MR)Fluid ; Magnetorheological Damper ; Knee Prosthesis ; Laboratory Bench Mark ; Dynamic Analysis

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