Concerted Control: Modulating Joint Stiffness Using GRF for Gait Generation At Different Speeds

This letter proposes a bio-inspired, simple, and easy-to-implement walking controller, termed Concerted Control, which leverages a shared common signal to coordinate movements across multiple joints without requiring predefined trajectories. The backbone of this controller is our previously developed Force Modulated Compliance (FMC) control concept, which modulates joint stiffness using ground reaction force (GRF). In Concerted Control, FMC is implemented across multiple joints, allowing implicit coordination through the shared GRF signal in absence of any centralized controller. We tested the performance of this controller on a simulated bipedal walker model and demonstrated that Concerted Control can generate human-like walking gaits across a wide range of speeds, from 0.7 to $1.8\,\text {m/s}$. Additionally, we assessed the robustness of these gaits against external angular momentum perturbations, and the results showed a high level of robustness. Concerted Control offers a promising approach for enhancing the control of bipedal robots and assistive systems.