Vibration-Based Assessment of Below Knee Prosthesis

Human locomotion is achieved through a series of gait cycles. The kinetic analysis of human walking indicates repeated cycles of ground reaction force GRF at the stance phase for each foot. Such a cyclic excitation force can induce vibration that can be transmitted to the human body. In patients using a prosthesis, such as a below-knee Bk prosthesis, the vibration response can cause undesirable effects, leading to discomfort and abnormal gait. In this work, a mathematical model is derived to analyze periodic vibration induced by GRF in the BK prosthesis. In this model, the transfer function of the prosthesis device was evaluated from experimental data with the aid of System Identification SID found in MATLAB software. Fast Fourier transform FFT is used to decompose the periodic GRF excitation and evaluate natural frequencies and responses. It has been found that the excitation frequencies of periodic GRF can affect prosthesis vibration at higher walking speeds and the vibration levels of human organs, including the abdominal, shoulder, lung, and spinal cord regions.