A bioinspired bistable robotic gripper with decoupled palm and finger reconfiguration

Existing soft grippers often suffer from slow actuation, continuous energy consumption during grasp maintenance, and limited payload-to-weight ratios, which restrict their application in dynamic and unstructured environments. In addition, fixed-geometry designs and multi-actuator architectures frequently compromise geometric adaptability and increase control complexity. To address these limitations, this paper presents a three-finger adaptive bioinspired gripper driven by prestressed tape springs, inspired by the dual-dimensional prey-capture mechanism of Drosera capensis and the basal-scale adaptation strategy of the octopus. A hierarchical bioinspired design is realized through a reconfigurable palm based on a crank-slider linkage for synchronous radial spacing adjustment, together with retractable, variable-length fingers that continuously adapt to objects of different sizes. A centralized cable-driven triggering mechanism exploits the bistable snap-through behavior of prestressed tape springs to achieve rapid compliant enveloping and zero-power grasp maintenance. A discrete rigid-segment kinematic model is developed to characterize the triggering and curling process, revealing a fully decoupled grasping workspace with a palm diameter ranging from 90-160 mm and finger lengths adjustable from 0-135 mm. Experimental results demonstrate closure times below 60 ms across all configurations, a payload-to-weight ratio of 18.75, and a 100% success rate in damage-free static grasping of 19 objects with diverse geometries, materials, and masses. The proposed design integrates biological adaptive capture strategies with a reconfigurable bistable architecture, providing an energy-efficient and low-dimensional solution for adaptive robotic grasping in unstructured environments.