In this study, in order to examine the optimal position of the armrest in the standing-up motion of the chair for the elderly grandmother, the standing-up motion from various positions was recorded and analyzed using a measuring instrument that can change the position of the armrest made by hand. As a result, the tip of the armrest is separated from the back of the knee to the rear side with respect to the chair in the range of 50 to 100 mm, the range of height 500 to 540mm from the floor was found to be the optimal position of the armrest in the standing-up motion of the grandmother's chair. In addition, we compared the results of the analysis of two other elderly people and ten young people. As a result, the optimum position of the armrest of the grandmother and two other elderly people was the same, and the optimum position of the depth of the armrest of the elderly and the young people, including the grandmother, was almost the same. However, the position of the height is different, the elderly height 500 to 540mm from the floor is the optimum position, young people height 580 to 600mm from the floor was the optimum position. The reason was 1) differences in the activity area of the body, such as the shoulder joint, 2) differences in muscle strength, and 3) differences in sensory feelings in the standing-up motion.Based on the above results, we designed and produced an easy chair exclusively for my grandmother.
