2.6 Ground reaction forces in amputee gait (🕒🕒💻)

The attached MATLAB file (GRF_data.mat) contains the horizontal component of the ground reaction forces (GRFs) for the left and right foot of an amputee walking with a passive prosthetic ankle. Unfortunately, you didn't do a great job with data organization when you collected the data, and you forgot to label which data column corresponded to the left foot and which one corresponded to the right foot. You do know that the data starts with right foot heel strike and includes two full right foot gait cycles, and the time associated with each data point is given in the first column.

(a) Plot the GRFs associated with the first column and the second column versus time. Based on the information that you know, which column represents data collected from the right foot force plate and which one is the left force plate?

(b) Find the maximum of the left and the right GRFs. Which one is greater, and by what percent?

(c) The right-foot heel strikes occur at 0 seconds and 1.458 seconds, while the left-foot heel strikes occur at 0.694 seconds and 2.114 seconds. Plot the time-synced GRFs of the first step from the left and right feet, with percent gait cycle on the horizontal axis. Which foot has the longer stride time?

(d) Based on your answers above, which do you think is the prosthetic foot and which is the biological foot? Why?