Abstract: A novel resistive exercise device designed based on spring mechanism is presented to help astronauts exercise in weightless environment. The core structure of the resistive exercise device is a completely passive spring mechanism, of which the elastic potential energy is designed to simulate the forces acting on the human body by the Earth gravity. Based on static force equilibrium, conditions for gravity force simulation of the device are proposed, and also the spring parameters are derived. The resistive exercise device and astronauts are modeled, and its performance is studied. Simulation experimental results demonstrate the feasibility of the proposed gravity force simulator, and the force acting on human body has a greater range of adjustment, even can be more than the normal Earth gravity. The greater loading of the resistive exercise device can be more suitable for countermeasure exercise of astronauts.

Key words: countermeasure to weightlessness, resistive exercise, spring mechanism, weightless environment