A novel active suspension gravity compensation system for physically simulating human walking in microgravity

Ground-based experiment of human locomotion in microgravity needs to partially compensate the influence of the earth gravity. This paper presents a novel design and preliminary experiment of an active suspension gravity compensation system, which can apply a desired constant vertical force at human body for physically simulating human walking in microgravity. The system composed of a passive static balancing mechanism to absorb high frequency impact and an active closed-loop controlled electric winch to provide the main compensation force. At desired compensation force of 505 N and walking speed of 3.6 kmph, the mean force error and the maximum force error of the presented system were 8 N and 35 N, respectively. The measured vertical ground reaction force data and motion data of the tested subject walking in simulated lunar gravity demonstrated the gravity compensation capability of the system. These studies can serve as a preliminary attempt to experimental investigations of human locomotion strategy in microgravity.