چكيده به لاتين
An amputated leg changes one's life drastically. It affects different aspect of their life and alters their physical and mental needs.
The main focus of this study is on providing a prosthetic knee in order to meet some physical needs of a transfemoral amputee. Therefore an active prosthetic knee comprising a four-bar mechanism which is being powered by a brushed DC motor has been designed, fabricated and its controller's been simulated.
In this study a motion generating four-bar mechanism is employed to meet a desired moving instant center of rotation and also to ensure mechanical stability of the prosthetic knee in stance phase. Efforts has been made to lower the size and weight of the proposed prosthesis using Artas SAM. This program is specifically developed to synthesize and analyze a mechanical mechanism and is able to provide various graphs such as displacement, velocity, acceleration, rotation, etc. of a specific element in a given mechanism. An elastic/viscoelastic element has been added to the mechanism as a shock absorber which in future studies will be used to correct gait patterns in a passive way. Using Solidworks the conceptual design has been turned to a mechanical design ready for fabrication, and a basic static structural analysis has been tried on the mechanical design to observe general deformations and to determine factor of safety of different parts of the desined prosthesis. The proposed prosthesis is modeled using bond graph modeling language and then the resulting model is interpreted to form a block diagram in order to make its simulation in MATLAB possible. For designing a PI-Like controller, fuzzy logic and its toolbox in MATLAB has been utilized and the resulting controller has been used to simulate the model. Simulation results for different standard input has been reported and discussed. In the Appendix section of this thesis a pseudo codes of the fuzzy controller based on an 8-bit Microchip microcontroller, basic transformations of physical elements to a bond graph model, an introduction to fuzzy logic and a fast tutorial on how to use Artas Sam to analyze a four-bar mechanism has also been added.
Keywords: Prosthetic knee, Robotic leg, Bond graph, Fuzzy control, Artas SAM
