One approach to solve this problem is that the robot stops immediately. However, biped humanoid robots generally fall over easily because their stability margin is small according to a restriction of support polygon and a high COG position. Therefore, it is necessary to improve fail-safe technology to prevent them falling over, to control the fall when falling is unavoidable, and standing by themselves in any state in addition to the walking mobility for working in a living environment. Morisawa et al. [25] suggested an emergency stop algorithm of a walking humanoid robot. Humanoid robots need to be able to stop quickly without falling. Since the timing of emergencies is unpredictable and they can occur at any state of robots, the stopping motion must be generated in real-time.