Weld n'Cut: Automated fabrication of inflatable fabric actuators

TL;DR

The paper addresses the challenge of labor-intensive, masking-based fabrication of textile-based inflatable actuators by introducing Weld n'Cut, an open-source platform that combines ultrasonic welding with an oscillating knife on a CNC gantry to automate fusion and cutting. The authors detail a Grasshopper-based design workflow and a material-characterization study that identifies TPU-coated Nylon as a robust choice for airtight bonds, achieving reliable actuation up to $50$ kPa. They demonstrate diverse actuator modalities, including fabric PneuNets and kirigami structures, capable of contraction, bending, twisting, and load-bearing, with quantified performance metrics such as contraction percent and threshold pressures. The platform promises scalable, precise manufacturing of soft textile actuators for wearables and rehabilitation devices, reducing manual labor and enabling complex, multi-material designs for safer, more capable soft robots.

Abstract

Lightweight, durable textile-based inflatable soft actuators are widely used in soft robotics, particularly for wearable robots in rehabilitation and in enhancing human performance in demanding jobs. Fabricating these actuators typically involves multiple steps: heat-sealable fabrics are fused with a heat press, and non-stick masking layers define internal chambers. These layers must be carefully removed post-fabrication, often making the process labor-intensive and prone to errors. To address these challenges and improve the accuracy and performance of inflatable actuators, we introduce the Weld n'Cut platform-an open-source, automated manufacturing process that combines ultrasonic welding for fusing textile layers with an oscillating knife for precise cuts, enabling the creation of complex inflatable structures. We demonstrate the machine's performance across various materials and designs with arbitrarily complex geometries.

Figures (5)

• Figure 1: The workflow of the Weld n'Cut platform.
• Figure 2: fabrication steps. A, Place a PTFE layer on the bottom, followed by two textile layers, and another PTFE layer on top. B Position magnets on top to secure the textiles and PTFE layers in place. C Lower the welder and begin welding the pattern onto the textile. D Once welding is complete, raise the welder and switch to cutting mode. E Create the cut line with the cutter. F The completed fabricated sample.
• Figure 3: Rectangular air pouches fabricated from diverse coated fabrics using the Weld n'Cut platform and inflated at $P=50$ kPa.
• Figure 4: Fabric PneuNets actuators. A Linear actuators. B Unidirectional and antagonistic bending actuators. C Twisting actuators with different deformation behavior.
• Figure 5: Kirigami actuators with a staggered linear cut pattern at different widths with multiple interconnected air channels. A. Uninflated, and B. inflated at $P=50$ kPa. C. using the Kirigami actuator with $w=125$ mm to lift a 50 g weight by applying $P=100$ kPa.