Stiffness Modulation in a Humanoid Robotic Leg and Knee

Stiffness modulation in walking is critical to maintain static/dynamic stability as well minimize energy consumption and impact damage. However, optimal, or even functional, stiffness parameterization remains unresolved legged robotics. We introduce an architecture for control utilising a bioinspired robotic limb consisting of condylar knee joint leg with antagonistic actuation. The replicates elastic ligaments the human providing tuneable compliance walking. Further, it locks out at maximum extension, when standing. Compliance friction losses between surfaces are derived function ligament length. Experimental studies validate utility through quantification of: 1) hip perturbation response; 2) payload capacity; 3) static mechanism. Results prove initiation lock can be modulated independently loss by changing elasticity. Furthermore, increasing co-contraction decreasing angle enables increased stiffness, which establishes counterbalanced decreased payload. Findings have direct application robots transfemoral prosthetic knees, where biorobotic design could reduce expense while improving efficiency stability. Future targeted involves power/weight ratios artificial limbs precision control.