Moving_VSEA: portable variable stiffness electroadhesive grippers for mobile manipulations

Electroadhesion (EA) enables electrically controllable, low-energy, and mechanically compliant gripping, making it attractive for robotic manipulations. However, stable electroadhesive grasping under dynamic disturbances remains challenging, particularly when soft EA pads are subjected to shear, impact, or vibration during motions. Variable stiffness electroadhesion (VSEA) offers a promising strategy by combining surface conformity in a compliant state with enhanced resistance to peeling in a stiffened state, yet its dynamic gripping performance has not been systematically investigated. Here, we establish dedicated experimental platforms to quantify VSEA performance under controlled lateral motion and collision disturbances, using in-house fabricated VSEA structures with tunable stiffness. Results show that while VSEA shows no intrinsic advantage over soft EA pads under static shear loading, it demonstrates significantly improved gripping stability under dynamic perturbations. Under high-speed emergency stops, VSEA sustains stable grasping up to 250 mm s⁻¹, significantly exceeding the 160 mm s⁻¹ limit of soft EA. In collision tests, VSEA maintains a stable grasp of a 400 g object under 1.7 m s⁻¹ impacts from a 13.61 g steel ball, outperforming both soft EA and stiffness-off configurations. Based on these findings, we develop a portable and an untethered mobile VSEA gripper capable of maintaining stable adhesion under lateral, longitudinal, and rotational shaking. This work provides a mechanistic understanding of stiffness-modulated electroadhesive gripping and establishes VSEA as a viable solution for mobile electroadhesive manipulations.