Design and development of mechanically controlled above knee prosthesis / Md. Sayem Hossain Bhuiyan
A mechanically controlled prosthesis is designed and developed to enhance the controllability of the conventional passive type prosthesis within an affordable price. Unlike to the typical mechanical prosthesis, the new design has made the prosthesis to follow the residual limb movements without h...
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| Format: | Thesis |
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2017
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| Online Access: | http://studentsrepo.um.edu.my/7776/ http://studentsrepo.um.edu.my/7776/2/All.pdf http://studentsrepo.um.edu.my/7776/9/sayem.pdf |
| Summary: | A mechanically controlled prosthesis is designed and developed to enhance the
controllability of the conventional passive type prosthesis within an affordable price.
Unlike to the typical mechanical prosthesis, the new design has made the prosthesis to
follow the residual limb movements without having any intricate guiding arrangement.
A gear based knee joint has made the prosthesis to move according to the residual limb
movement. A spring based ankle joint, on the other hand, helped the amputee to
overcome the difficulties in producing required flexion and extension in their prosthetic
feet. It also expedited the energy storing and returning quality of the prosthetic ankle. A
torsion spring has enabled the ankle joint to rotate in a controlled way to any desired
angle without demanding any additional setup. The gear based knee joint is designed to
improve the performance of mechanical type above-knee prostheses. The gear set with
some bracing, and bracket arrangement is used to enable the prosthesis to follow the
residual limb movement. The proposed design of the ankle joint would enable the
mechanical type ankle joint to overcome the limitation of stability, flexion and
extension within an affordable price. This would enhance the range of motion of the
mechanical type prosthesis without incorporating any expensive electronic devices into
the ankle joint. Unlike the typical mechanical prosthesis, the new design would allow
the prosthesis to bend forward and backward to any desired angle with enough stability.
The pattern of the prosthetic gait cycle shows that the spring based ankle joint could
imitate the movement of the prosthesis closely to the biological limb. The motion
analysis and finite-element analysis (FEA) of knee joint and ankle joints components
were carried out to assess the feasibility of the design. The FEA results were then
compared with the real data obtained from the healthy subject. Stability analysis under
disturbance and gait analysis during walking with the prosthesis was carried out to test the performance of the prosthesis. According to the simulation results, the patterns of
kinematic and kinetic parameters profiles have shown a great resemblance with that of
the gait cycle of a healthy biological limb. The factor of safety obtained from the stress
analysis results of FEA was 3.5 and 4.9 for knee joint and ankle joint components
respectively, which indicated to no possibility of design failure. From the performance
analysis results, though the exact shape and amplitude of the motion analysis results
were deviated 0.5 to 14 times than the healthy gait cycle data, the trend of the curves
were still in good agreement. At dynamic platform setting, the overall postural stability
was found to improve by 3.3 to 5 times, and fall risk was observed to increase by 1.2 to
3.3 times while using prosthesis; whereas at static platform setting, the postural stability
and fall risk performances were found to decline by 1.3 times and by 1.8 times
respectively. Finally, the cost of quasi-active type above knee prosthesis designed for a
lower limb amputee was found considerably cheap and thus affordable for mass
proportion of amputee. |
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