Figure 9
From: Simulation-based biomechanical assessment of unpowered exoskeletons for running
Joints’ trajectories and definition of kinematic indexes. In this figure, (a–c) show the hip, knee, and ankle joints’ trajectories, respectively. The start of the gait cycle is at the heel-strike instant of the right leg, and the swing phase is shown with a dashed line over the horizontal axes. Figure (a) shows the hip joint trajectory and the definition of kinematic indexes. In figure (a), A is the maximum angle of the left hip joint, B is the minimum angle of the right hip joint, and C is the absolute value of the difference between A and B. It is important to note that A and B are vectors and can be either positive or negative, and C is a distance, and it is always positive. As discussed “A kinematic index for metabolic rate reduction” section, the kinematic indexes are defined as range of motion (RM) = \(C=|A-B|\), symmetry of motion (SM) = \({|A+B|}^{-1}\), and RS \(=\) RM \(\times\) SM = \(C\times {|A+B|}^{-1}\); |x| means the absolute value of x.
