Principle, design and characterization of a human-inspired flexible mechanism for capturing non-cooperative targets

Abstract

Inspired by the biomechanics of human shoulder and elbow joints, this study proposes a novel 4-DOF human-inspired flexible mechanism (HIFM). The HIFM integrates a dual-mode operational characteristic that combines rigidity and flexibility, with a particular emphasis on its flexible mode, which significantly enhances the safety and stability of capturing non-cooperative targets. First, a dynamic model of the flexible spacecraft system, incorporating the HIFM and a post-capture compound spacecraft with active attitude control, is developed using Kane’s method. Second, a series of simulations, including numerical and virtual prototype testing, as well as experimental validation using an air-flotation microgravity testbed, are conducted to assess the HIFM’s performance. Comparative analysis with a single-DOF bio-inspired isolation (BII) system and traditional rigid capture method demonstrates that the HIFM exhibits superior omnidirectional buffering performance during the capture phase, achieving a peak values of impact force-torque reduction of up to 84.11% while effectively preventing abrupt changes in the motion state of the spacecraft base. In addition, the HIFM significantly enhances the controllability and robustness of the post-capture compound system, achieving 37.5% reduction in attitude adjustment time and 1.42% decrease in energy consumption. Moreover, the HIFM extends the contact duration between the target and the service spacecraft by at least 2000%, thereby creating a critical operational window for the capture mechanism. Overall, this study not only provides a theoretical and practical framework for passive compliance mechanisms in non-cooperative targets capture but also lays the groundwork for future research on optimization control for space missions. These findings significantly enhance the reliability and efficiency of spacecraft servicing operations.