The current method of gait analysis has several limitations for determining gait stability, such as a complicated preparation process, repeated experimental procedures that are time-consuming, and financial burden of experiments. This study investigated whether gait stability could be analyzed using only the COM-COP (Center of Mass-Center of Pressure) inclination angle connecting COM and COP. COM and COP coordinates were obtained from a motion analysis system for a total of 40 elderly and young subjects. The COM-COP inclination angle that changed in real time during level walking was then analyzed to obtain gait stability on each of sagittal and frontal planes using these coordinates. As a result, the gait symmetry index on the sagittal plane did not show a statistically significant difference between young and elderly subjects (First Step, p = 0.189; Second Step, p = 0.711). On the frontal plane, elderly subjects showed 0.39 degrees (p = 0.058) and 0.5 degree (p = 0.03) larger side-to-side sway angles in the first and second steps than young subjects, respectively. Gait stability can be analyzed using a more simplified experimental method with minimum amount of data in future gait analysis.

Patients with complete paralysis that only walk with the assistance of exoskeleton robots because they lost their ability to walk. However, robots do not allow the exoskeleton robot to grasp the current state before walking and change the walking pattern. A "Stability Circle Region" was proposed to determine the current state of the exoskeleton robot. The Stability Circle is an area that can determine the possibility of a fall situation before the next walk using the link parameters of the robot and the current center of gravity of the patients. This study verified the validity of "stability circle" by simulating the change in the center of mass. Simulation results can be used to determine the stability of walking depending on whether the position of the center of mass before the walking is included in the circle area.