Robotic Threading from a Gel-like Substance Based on Impedance Control with Force Tracking

Gel-like matter is used extensively in a wide range of application fields including industrial applications such as the manufactory and assembly of garment and footwear products, soft macro/micro-robotics, medical diagnostics, and drug delivery. However, the manipulation of gel-like matter is very challenging, due to its high deformability, high viscosity, and fast phase changing. In this letter, we propose a novel biomimetic robotic fiber threading approach based on impedance control with force tracking. The highly integrated approach can control the impedance of the fiber during both threading and solidification of the fiber and characterize the mechanical properties of the fabricated fibers in the very same setup without changing parts. The impedance control method has also been adapted in this letter by adding a real-time estimator for continuously estimating the stiffness of the threading force for highly accurate control. The resulted fibers using the proposed approach demonstrates higher performances in all terms of toughness, stiffness, elongation and strength, compared to the traditional velocity controlled fiber fabrication approach.