A Compact Annular Electrostatic Clutch Joint: Dynamic Response Modeling and Time‐Sharing Control for Underactuated Robots

Electrostatic clutches offer immense potential for programmable variable stiffness in multi‐degree‐of‐freedom (DOF) robotic systems. However, their practical deployment in continuous motion is fundamentally bottlenecked by two challenges: spatial constraints in existing parallel‐plate configurations and the lack of electromechanical coupling models for dynamic response. Here, we developed a compact, modularly configurable electrostatic clutch joint (ECJ) utilizing a closed annular configuration. Based on fracture failure mechanics, such a design ensures a consistent adhesive interface during rotation. Furthermore, we establish an electromechanical coupling model and an experimental characterization framework to reconstruct the transient force capacity curve, thereby elucidating the mechanisms by which velocity and external loads impair dynamic electroadhesion. Leveraging such a theoretical and experimental framework to address response delays caused by residual polarization, we propose a biphasic amplitude‐frequency modulation (BAFM) strategy that deploys a low‐voltage, high‐frequency electric field upon desorption, thereby yielding a 52.8% improvement in detachment efficiency. The above hardware and theoretical advancements are validated through a time‐sharing control scheme in an underactuated robotic finger, achieving smooth and rapid multi‐joint coordination. Crucially, the system's modular deployability is demonstrated by independently controlling an 8‐DOF continuum robot using only 2 actuators, successfully enabling agile shape‐morphing and navigation through narrow, highly constrained environments, such as curved pipelines and aero‐engine blades. Ultimately, such an integrated approach may establish a new paradigm for highly dexterous, lightweight, and adaptable robotic systems.