Symmetry-Based Modeling and Hybrid Orientation-Force Control of Wearable Cutaneous Haptic Device

We propose novel symmetry-based modeling and hybrid orientation-force control frameworks for cutaneous haptic device (CHD) to generate precise three degree-of-freedom (DoF) contact force on the fingertip robustly against user variability. The CHD hardware is designed in a form of an underactuated cable-driven parallel mechanism, with springs placed along the tendon to stabilize the pose. We analyze the kinematics of the CHD and propose a pose estimator by exploiting the symmetrical nature of the mechanism. We then devise a hybrid orientation-force controller to track the direction and magnitude of the desired contact force simultaneously in a feedback manner for control accuracy and robustness. We also adopt a tension regulator to mitigate friction effect during the actuation. Experimental validation and demonstration show the efficacy of the CHD with our proposed estimation and control framework.