Registration of ankle angle kinematics data using functional data analysis for parachute landing fall activity

Registration is an essential phase in Functional Data Analysis (FDA). The purpose of this study was to examine the efficiency of using landmark and continuous registration on ankle angle data during the parachute landing fall activity. Twenty-one Malaysian forces participated in this experiment: three were professional parachutists and the other eighteen were amateurs. The movements were recorded using two cameras GoPro Hero 4, and the software Quintic Biomechanics Software v26 was chosen to extract the ankle angle data. The registration process can be accomplished in two ways: landmarks and through continuously. After landmark registration, continuous registration is an additional technique to improve curve alignment. According to the RMSE test, the ankle angle curve was aligned very effectively by applying the landmark registration with additional continuous registration, where the data yielded the smallest root mean square error (RMSE) values for both amateur and professional categories, which were 8.359 and 9.642, respectively. Furthermore, the registration technique improves the accuracy of average ankle angle measurements.