Quasi-Passive Vertical Compensation for Accurate 6-DOF Physical Simulation of Microgravity Collision During Landing on Small Celestial Body

Exploring small celestial bodies, such as asteroids, opens new avenues for space exploration, complementing lunar and Martian missions. However, the microgravity environment (∼10−5g) presents significant challenges, particularly for landing. Accurate prelaunch testing of mechanical and control systems is crucial to ensure mission success. Therefore, the ground-based microgravity physical simulation is essential, particularly for accurately replicating its microgravity collision response. However, existing microgravity simulations fail to accurately replicate landing collision response, particularly in the vertical direction. In this article, an air-bearing simulation system with quasi-passive vertical compensation is presented, enabling 6-DOF simulation. The vertical compensation integrates a quasi-zero stiffness unit for passive gravity compensation, complemented by an active following mechanism for extended compensation stroke. The controller is specifically adjusted to generate the vertical virtual mass, ensuring equal added mass in all three directions and eliminating systematic errors. Vertical tests confirm that the system effectively simulates free-floating conditions for the lander simulator up to 1 ton and accurately responds to forces as small as 1 N. The proposed 6-DOF physical simulation system provides a novel technical approach and has been implemented in the ground verification of theTianwen-2exploration mission.