Fast stiffness variation gripper with efficient adhesion control

Abstract

The mushroom-shape gecko-inspired adhesive has been extensively studied and applied in a wide range of fields. However, current research primarily focuses on enhancing its adhesion properties, necessitating further exploration in strategies of detachment and adaptation, which significantly constrain its practical applications. In this study, a stiffness variable gripper with controllable adhesion and fast response is developed by integrating mushroom-shape adhesive with granular jamming technology. A theoretical model for the detachment of the gripper is established, indicating the effect of backing stiffness on adhesion performance, which is verified through contact area observations and adhesion experiments. The proposed modulation method demonstrates an impressive adhesion-to-detachment ratio of 92.8, with adhesion capacity of up to 41.023 N and detachment force of only 0.442 N. The switch time is remarkably fast at just 0.5 s. Additionally, the designed gripper, under pressure difference of 60 kPa, is able to stably grasp smooth objects with various shapes weighing over 2 kg, with a load-to-weight ratio of approximately 8, and a minimal power consumption of only 4.404 W. The work here presents a comprehensive understanding of adhesion modulation of fibrillar adhesive through granular jamming, and provides new insights into robust reversible adhesion design for related technologies.