Tool changing 3D printer for rapid prototyping of advanced soft robotic elements

Abstract

In the field of soft robotics, pneumatic elements play an important role due to their sensitive and adaptive behavior. Nevertheless, the rapid prototyping of such actuators is still challenging since conventional 3D printers are not designed to fabricate airtight objects or to specify their bending behavior by combining materials of different stiffness. In order to address this challenge, a tool changing multi-material 3D printer has been constructed, which can be equipped with various print-heads fitted to the specific application. By alternately processing filaments with varying mechanical properties, a series of pneumatic elements was produced. The actuators were printed in thermoplastic polyurethane with shore hardness A70 for flexible parts and D65 for stiff parts. A novel procedure for the feature adaptation of the flow rate allowed the fabrication of vertically printed flexible membranes with a thickness of just 500 μm. This way the bending and expanding printed structures can all be actuated with a pressure of 100 kPa or less. Furthermore, a new kind of generic actuator that is customizable to specific tasks and can perform complex motion behavior was designed. All together, these actuators demonstrate the high potential of the developed platform for further research on and production of soft robotic elements and complex pressurized systems.

Design of Dual-Head 3D Printer

“…On the one side, it is always provided with a pocket for screwing on the contact of the electromagnet (3), and the other side with two smaller pockets (4) for accommodating neodymium magnets serving for anchoring in the correct position. On the same side where the contact of the magnet is located, there is also a pocket for screwing the guide pin (5) in the lower part. The extruder cover ( 6) is also screwed to the extruder carriage with four M3 screws.…”

“…The entire extruder cover is bolted with six M3 screws, both to the extruder carriage and to the fan cover (4). The hexagon nuts that tighten the fan cover are housed in rectangular pockets on the sides of the extruder cover (5). The extruder cover is printed in two pieces -each for one extruder carriage.…”

“…With the management of the electronics and control of the device, the possibility of precise flow control was achieved even with sharp changes in the speed and direction of printing. Due to the need to print airtight soft products for application in soft robotics and pneumatics, according to Conrad et al [5] designed printhead replacement device. This tool changer allows you to print flexible products large for pneumatic applications with great precision.…”

Early career scientists converse on the future of soft robotics

“…Soft robots are compliant machines often fabricated from flexible materials such as silicones or thermoplasts. Recent developments enable their manufacturing via 3D printing using soft inks or flexible TPU filaments (Wehner et al, 2016;Slesarenko et al, 2018;Skylar-Scott et al, 2019;Conrad et al, 2020;Conrad et al 2021;Conrad et al 2022;Kappel et al, 2022). Most soft robots utilize compliant pneumatic actuators from flexible materials for movement (Whitesides, 2018;Esser et al, 2019a).…”

Editorial: Living Machines: From Biological Role Models to Soft Machines

“…In the fourth article, Conrad et al [18] highlight a novel tool changing specialized multi-material fused deposition modelling (FDM) 3D printer for the rapid prototyping of soft robotic elements. The system is equipped with four FDM print heads, which can print from stiff PET to flexible TPU for every filamentbased printing material.…”