Development of a compliant spine mechanism for enhanced humanoid robotics locomotion

Humanoid robots often employ rigid-trunk designs which limit locomotion capabilities and payload capacity. This paper presents a novel bio-inspired, tensegrity-based flexible spine mechanism designed to address these limitations. The design integrates a modular, multi-segment structure combining rigid struts and flexible TPU cables, creating a compliant, stable, and adaptable spine. We developed a novel dynamic model of this tensegrity-based spine to analyze its motion characteristics, providing detailed insights into its load-bearing capabilities and range of motion. Experimental results, obtained using a novel humanoid robot platform ("Flexinoid"), demonstrate improvements in locomotion performance. Furthermore, the design mitigates non-linear movement challenges, allowing for an enhanced range of flexion to -30°:65° and lateral bending by ± 30°. The experimental results confirm an increase in sensitivity and a decrease in the minimum detectable payload following the onset of motor back-driving, validating the effectiveness of the passive energy storage mechanism during initial loading. This enhancement in performance underscores the potential of this bio-inspired design for applications requiring precise control and high payload capacity. This research presents a novel approach to humanoid robot design, paving the way for more versatile and capable robots in various applications.