Enhanced Deformation Resistance and Load-Bearing Capacity in Tip-Growing Robots Through Scale-Inspired Layer Jamming Mechanism

The tip-growing robot, constructed from flexible film or nylon and powered by fluid pressure, has exhibited superior motion performance and high adaptability in complex and restricted environments for detection and manipulation. However, the insufficient stiffness caused by its flexibility limits its ability to carry heavy loads in long and complex three-dimensional spaces. To address this, the study proposed a novel layer jamming mechanism inspired by the subcutaneous scales of freshwater eels. The discrete and continuous flaps, integrated and jammed between the designed double-layered body, increase the global stiffness without impairing tip eversion and steering capabilities. The internal pressure driving the eversion replaces the conventional vacuum system to provide the compression force, reducing lag and complexity. Additionally, the tip interspace between the two body layers ensures steering flexibility of the hardening robot and realizes shape locking post-deformation. The test shows that this mechanism increases the bending stiffness, torsional stiffness, and joint stiffness of the robot by 4.6, 7.8, and 8.7 times, respectively. Further, we demonstrate and verify the long-distance movement and superior carrying abilities in three-dimensional spaces, confirming that the tip-growing soft robot with jamming layers has broader application potential.