3D printing non-assembly compliant joints for soft robotics

This paper investigates integrating non-assembly three-dimensional (3D)-printed joints and soft robotic muscles in order to make a tendon-driven robotic finger. A finger-type structure actuated by electro-thermal soft actuator mechanism is introduced, including a bio-inspired 3D-printed compliant joint. As an affordable but high-performance component, twisted and coiled polymer (TCP) is used to drive the system as an actuator. The Euler–Lagrangian method and a transfer function based on an electro-thermo-mechanical model are used to analyze finger joints. The compliant joints are non-assembly 3D-printed spiral springs with high customization capabilities incorporated into the model. The simulation analysis is conducted to elucidate how the electro-thermal muscle and the spiral spring joint properties influence the finger motion. The results reveal further understanding of the 3D-printed spiral spring joints effects on the behavior of the soft robotic limbs. The suggested method can be adapted and employed in a broad variety of medicinal and industrial applications. •A 3D printing approach is set for the development of a non-assembly compliant joint for soft robotics.•Spiral spring joints with variable stiffens are manufactured and characterized experimentally.•Non-assembly joints enabled rapid prototyping of the soft robots.•Simulation and modeling are used to demonstrate the performance of the soft robotic muscle.