Figure 3
From: Age-related and obstacle height-related differences in movements while stepping over obstacles
COG (center of each segment). The body was divided into seven segments (1, Trunk; 2 and 3, both the thighs; 4 and 5, both the lower thighs, and 6 and 7, both feet) defined by ten markers. The virtual value calculated with a software that estimated the equation of Ehara and Yamamoto [23] was considered as COG (Figure 3). Center of seven segments were calculated. COG was calculated as composition center of seven segments. xg = m 1 x 1 + m 2 x 2r + m 3 x 3r + m 4 x 4r + m 2 x 2l + m 3 x 3l + m 4 x 4l; yg = m 1 y 1 + m 2 y 2r + m 3 y 3r + m 4 y 4r + m 2 y 2l + m 3 y 3l + m 4 y 4l; zg = m 1 z 1 + m 2 z 2r + m 3 z 3r + m 4 z 4r + m 2 z 2l + m 3 z 3l + m 4 z 4l. Mass ratios of each segment (m 1: trunk 0.66, m 2: thigh 1, m 3: lower thigh 0.05, m 4: foot 0.02) x 1: center of trunk, x 2r: center of right thigh, x 3r: center of right lower thigh, x 4r: center of right foot, x 2l: center of left thigh, x 3l: center of left lower thigh, x 4l: center of left foot (Note: For information on how to calculate the center of seven segments, see Ehara and Yamamoto [23], pages 12 to 15).