An enhanced cascade constant-force system based on an improved low-stiffness mechanism

Dynamic constant-force performance is essential in suspended astronaut micro-gravity simulation systems. Of particular concern is the active constant-force system comprising a low-stiffness mechanism because of its combination of high-speed response and low stiffness. However, existing simulation systems demonstrate limited performance owing to large amounts of additional mass, difficulties in the fine adjustment of setting force, and low bandwidths. Improving on our previous work, we present a cascade constant-force system with an improved lightweight low-stiffness mechanism. In particular, the proposed system employs an innovative setting force adjusting mechanism with low inertia and a large reduction ratio obtained using a reverse-drive screw and nut mechanism. An in-depth theoretical analysis is conducted to reveal the disturbance suppression characteristics of the low-stiffness mechanism and actuator at different frequencies. The enhanced performance obtained using the low-stiffness mechanism was verified experimentally. It was shown that the improved mechanism significantly increases the system bandwidth and achieves an enhanced dynamic constant-force performance.