Motion measurement method and motion measurement system

A motion measurement method, which is applied to measure a motion trajectory of a machine, comprising:

• a motion measurement point defining step, wherein a central rod is installed onto a main spindle of the machine, one end of the central rod is connected to a central ball, and a motion measurement point is defined at a center of the central ball;
• a reference socket mounting step, wherein a first reference socket and a second reference socket are mounted on a worktable of the machine;
• a measuring bar installing step, comprising:
• attaching a first measuring ball to a first measuring bar and connecting the first reference socket and the central ball with the first measuring bar;
• and
• attaching a second measuring ball to a second measuring bar and connecting the second reference socket and the central ball with the second measuring bar;
• and
• a motion measuring step, wherein a first reference point is defined at a center of the first measuring ball, a second reference point is defined at a center of the second measuring ball, the central ball connected by the central rod is driven by the machine such that each of the first measuring bar and the second measuring bar is extended or shortened, and a coordinate of the motion measurement point and the motion trajectory of the machine are obtained according to a first measuring distance between the first reference point and the motion measurement point measured by the first measuring bar which is connected between the central ball and the first measuring ball, and a second measuring distance between the second reference point and the motion measurement point measured by the second measuring bar which is connected between the central ball and the second measuring ball, in association with a first reference distance between the first reference point and the second reference point.