Adjustable Constant-Force Mechanism Principle Exploration, Design and Experimental Verification

Constant-force mechanisms are pivotal in tensioning systems and vibration control for large-space membrane structures. To address the demands of such structures, this study presents a novel adjustable compliant constant-force mechanism characterized by a simplified structure and facilitated standardization. This mechanism consists of a positive-stiffness tension spring component and a negative-stiffness S-shaped nonlinear spring component connected in parallel, forming its core configuration. The paper elaborates on the mechanical design, stiffness superposition principle, and key concepts underlying the component design. To enhance performance, a multiparameter optimization method is proposed, which integrates finite element modeling with a Bayesian optimization strategy. A prototype was subsequently fabricated and tested using the optimized parameters. Experimental results demonstrate that the prototype achieves the desired near-zero stiffness behavior within its effective working range while enabling stepless adjustment of load-bearing capacity. This research provides an innovative solution for the design of constant-force mechanisms in large membrane-structured spacecraft applications.