Seamless Transition Control in Spring-Legged Quadrotors: A Hybrid Dynamics Perspective with Guaranteed Feasibility

Hongli Li, Botao Zhang, Rui Mao, Tao Wang, Hui Cheng

Abstract: Legged aerial-terrestrial robots have garnered significant research attention in recent years due to their enhanced environmental adaptability through combined aerial and terrestrial locomotion. However, existing passive spring-legged aerial robots exhibit limited motion versatility, demonstrating single stance gait during ground impacts, which constrains their task adaptability and creates substantial challenges in hybrid trajectory optimization and switching control. To address these difficulties, this work presents a systematic solution to achieve diverse hybrid locomotion. We innovatively establish the differential flatness property for spring-legged quadrotors in both aerial and terrestrial domains, and propose a unified hybrid trajectory optimization framework that generates smooth, agile, and dynamically feasible multi-modal trajectories incorporating diverse stance gait patterns. Furthermore, a hybrid nonlinear model predictive controller with a trajectory extension strategy is developed to enhance hybrid tracking precision and mode transition execution. Compared to existing methods, we achieve a 27% reduction in tracking error during hybrid locomotion while maintaining high-precision foot placement. The source code will be released to benefit the community¹

External IDs:dblp:conf/iros/LiZMWC25