  Robotic grippers with visuotactile sensors have access to rich tactile
information for grasping tasks but encounter difficulty in partially
encompassing large objects with sufficient grip force. While hierarchical
gecko-inspired adhesives are a potential technique for bridging performance
gaps, they require a large contact area for efficient usage. In this work, we
present a new version of an adaptive gecko gripper called Viko 2.0 that
effectively combines the advantage of adhesives and visuotactile sensors.
Compared with a non-hierarchical structure, a hierarchical structure with a
multimaterial design achieves approximately a 1.5 times increase in normal
adhesion and double in contact area. The integrated visuotactile sensor
captures a deformation image of the hierarchical structure and provides a
real-time measurement of contact area, shear force, and incipient slip
detection at 24 Hz. The gripper is implemented on a robotic arm to demonstrate
an adaptive grasping pose based on contact area, and grasps objects with a wide
range of geometries and textures.
