Autologous Variable Stiffness Soft Finger Based on Cross-Layer Jamming for Multimode Grasping

Layer jamming variable stiffness technologies have been widely explored to enhance the load-bearing capacity of soft robotic fingers. However, these technologies typically require layer-jamming units to be attached to soft actuators as additional components, complicating structural design and limiting flexible multiconfiguration actuation. To address these problems, we propose an autologous variable stiffness soft finger (AVSSF) that integrates the cross-layer jamming joints (CLJJs) as both the variable stiffness unit and the finger itself, actuated by tendons. This design ensures a simple and compact structure while offering a wide range of stiffness adjustment. Additionally, by coordinating tendon actuation with the control of the CLJJ's jammed and unjammed states, the AVSSF achieves multiple configurations, providing flexibility in operation. Experimental results demonstrates that the stiffness of the AVSSF increased by a factor of 79.5 after modulation. We develop a two-finger gripper based on this design, capable of executing four distinct grasping modes: power grasp, adaptive pinch, expansion grasp, and hook. This gripper demonstrates adaptability to various objects and environments, highlighting its potential for diverse applications. In summary, this work offers insights into the advancement of autologous variable stiffness technologies and the development of multimodal grasping capabilities.