A gecko-inspired adhesive robotic end effector for critical-contact manipulation

It is an emerging challenge for robots to achieve non-destructive pick-and-place manipulation for delicate objects under low normal preload, i.e., critical-contact manipulation. The prominent on-off controllable property of the gecko-inspired microwedge adhesive makes critical-contact manipulation possible for robotic end effectors. However, it is difficult for end effectors to actuate the micron-scale microwedge adhesive and detect the adhesion state. In this paper, a gecko-inspired adhesive robotic end effector for critical-contact manipulation is proposed, which consists of a half-scissor variable-scale actuator, a 3-axis high-sensitivity isotropic flexible capacitive tactile sensor, and the microwedge adhesive. The half-scissor variable-scale actuator is designed to provide pure large shear loading for the microwedge adhesive at micron-scale displacement by merely controlling the normal macro-scale displacement of the actuator. Besides, the 3-axis high-sensitivity isotropic flexible capacitive tactile sensor is designed for accurate detection of multi-axis contact forces and the adhesion state between the adhesive and objects to ensure the success of the critical-contact manipulation. The sensor can sense the shear and normal forces by detecting variations of the overlap and distance between electrodes, while the design of the finger-like electrodes improves the sensitivity. In addition, a set of experiments on manipulating objects are implemented and the results show that the proposed robotic end effector can provide pure large shear loading for the microwedge adhesive at micron-scale displacement and can detect the adhesion state between the microwedge adhesive and objects accurately to stably grasp delicate objects in critical-contact condition.

Automated summary

This paper proposes a gecko-inspired adhesive robotic end effector for critical-contact manipulation. The end effector consists of a half-scissor variable-scale actuator, a high-sensitivity isotropic flexible capacitive tactile sensor, and a microwedge adhesive. The actuator provides large shear loading for the adhesive through controlling the normal displacement, while the sensor accurately detects contact forces and adhesion state. Experimental results demonstrate that the proposed robotic end effector can stably grasp delicate objects in critical-contact condition.