Researchers at the University of California use 3D printing to create “insect-like” soft robots

China3D printingNet, June 11, researchers at the University of California, San Diego have used3D printingTechnology has produced a soft and flexible walking “insect-like” robot.
The additive manufacturing technology used to make robots can reduce3D printingThe cost of entry for soft robots and opening up new applications of the technology in places that are not safe for humans (for example, navigating in disasters or war zones).

“We hope that these flexible skeletons will lead to the creation of a new type of biologically-inspired soft robot.” said Nick Graves, a professor of mechanical engineering at the Jacobs School of Engineering at the University of California, San Diego. It’s easier for people to build soft robots.”

make3D printingSoft robots are more accessible

According to the researchers, one of the main challenges in generating insect-inspiring robots is the complexity of reshaping the mechanics of the exoskeleton structure. The shell needs to perform multiple functions, including structural support, joint flexibility and body protection, while providing functional surface features for sensing, grasping and adhesion.
What the San Diego research team observed is that insect limb mobility is determined by the arrangement of rigid, soft and gradual stiffness elements, while insect exoskeleton is a mixed structure of rigid and soft mechanical parts. Therefore, future iterations will require a hybrid construction method to better reflect the insect models on which they are based.

Previous attempts to create insect-inspired robots required the use of multiple materials3D printingMachine and multi-step casting process. For example, scientists at the University of Rochester created a jumping robot insect inspired by water riders in 2015. However, according to the San Diego researchers, this biologically-inspired robot looks more like a rigid industrial robot, including rigid links and rigid high-speed-ratio electric motors.Recently, roboticists have started to use multi-material3D printing, Laser cutting, lamination and die-casting methods, incorporating the adaptability of the body and limbs into the robot design. These manufacturing techniques also have disadvantages because they usually come at the expense of acquiring expensive and time-consuming manufacturing tools, which provide limited material options.

In order to enable them to be more cost-effective3D printingFlexible and elastic exoskeleton, the research team designed a novel hybrid method called elastic bone printing. Use Fused Deposition Modeling (FDM)3D printingMachines and standard filament materials (such as acrylonitrile butadiene styrene (ABS)) make this method cheaper and easier to use. In addition, the new technology is different from traditional methods, but by printing 3D rigid filaments directly onto heated thermoplastic films to create soft robots. This method provides a flexible and strong base layer for the deposited material, and can precisely control the stiffness and characteristics of the joints and struts in the robot body.



The manufacturing technology of the flexible skeleton was inspired by insect shells. Picture from Soft Robotics.

Additive manufacturing of “insect-like” soft robots

In standard FDM printing, plastic filaments (such as ABS or polylactic acid (PLA)) are extruded through the orifice of a heated nozzle and deposited on a flat printing surface. On the other hand, the flexible skeleton process uses modified Prusa i3 MK3S or LulzBot Taz 6 FDM 3D printingMachine, the filaments are deposited directly onto the heated thermoplastic base layer. This results in a high bond strength between the deposited material and the non-extensible flexible substrate, thereby improving fatigue resistance. The bonding process of flexible skeleton printing also does not require additional adhesives or curing agents, because the filaments are directly bonded to the base layer during the extrusion process.

To test the strength and fatigue resistance of the produced components, the team fabricated flexible beams with a uniform rectangular geometry. Bend each beam to a constant stress state and hold that position for 10 seconds to simulate the situation where the robot leg is bent and fixed in position to support the load. Then, the research team measured the creep angle of the beam by taking an image of the unloaded beam deflection angle, which was measured from a neutral position before the test.By adding a layer of polycarbonate (PC), researchers in San Diego found that they were able to3D printingThe creep deformation of the beam is reduced by 70%.

To demonstrate the walking ability of the robot produced using the flexible bone production method, the team built a quadruped walking robot driven by tendons. The robot’s chassis is designed and assembled with limbs produced from fully flexible bones, and is driven by four micro servos.The length of the two legs is 70 mm, and each leg takes 30 minutes to perform3D printing, And has two joints: one for bending and one for stretching. After the production of the entire robot is completed (it takes about three hours), each limb is inserted into the robot chassis (main body) and connected to a micro-servo through a tendon and a winch. The final product has interchangeable legs, which are designed for different terrains, and during the test, the completed robot can reach a speed of nearly 5 centimeters per second.
The external structure of the flexoskelton robot can not only protect its internal components, but also can mix soft and rigid components, so that it can be produced in a complex 3D layout. According to Gravish, the innovative production technology used to create robots may allow the production of new multifunctional robots for use in factory environments.“The ultimate goal is to create an assembly line that can print the entire flexible skeleton robot without manual assembly. A small group of such small robots can do the work of a large robot alone, and more.” Gravish said.

The construction process of a flexible skeleton robot. Picture from Soft Robotics.
3D printingSoft robot
In recent years, research on the additive manufacturing of soft robots has taken many forms.For example, in January 2020, Cornell University researchers developed a3D printingThe muscles of the soft robot can “wick sweat.” Using a hydrogel-based composite resin and stereolithography (SLA), a soft finger-like actuator that can retain water and respond to temperature is produced.
In August 2019, researchers from the Delft University of Technology (TU Delft) in the Netherlands created a multicolor3D printingSensors to help soft robots improve self-awareness and adaptability.By innovating a flexible embedded3D printingFor sensing methods, researchers have increased the interaction between robots and objects.
A pair of NASA researchers announced that they have been3D printingUsed in3D printingTechnology to produce a soft robot actuator in May 2019. This new component is responsible for providing animation and control functions for the moving parts of the robot, and represents an important step in bringing soft robotics technology into space.

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