Anti-falling of wheeled humanoid robots based on a novel variable stiffness mechanism

Abstract Wheeled humanoid robots have garnered significant research attention; however, their applications in close, diverse human-robot interaction remain limited due to unresolved safety and dynamic stability challenges. The human-scale body size of these robots typically results in substantial mass and elevated center of gravity, creating challenges in dynamic control and increasing fall risk during collisions. To address these challenges, this study proposes a variable stiffness mechanism (VSM) for wheeled humanoid robots that integrates vibration mitigation, falling prevention, and damping capabilities to minimize damage to both humans and robots during collisions. Comparative analysis demonstrates that robots equipped with the proposed VSM exhibit enhanced damping performance and reduced roll angles post-collision compared to conventional rigid payload-carrying wheeled mobile robots. The mechanism demonstrates superior impact force resistance, preventing falls during dynamic impact experiments. This innovation addresses critical safety concerns in wheeled humanoid robots, facilitating applications requiring close human-robot interaction.