Researchers create electronics-free robotic gripper with 3D printing

The soft gripper can be put to use right after it comes off the 3D printer and is equipped with built-in gravity and touch sensors.
Jijo Malayil
The 3D-printed soft robotic gripper
The 3D-printed soft robotic gripper

UC San Diego 

Imagine if 3D printers can produce robots that can work straight out of the block. This concept was made possible by a team of researchers from the University of California San Diego and BASF corporation. Their efforts have led to a robotic gripper that can be printed in a go and doesn't need any electronics to work.  

According to the team, the soft gripper can be put to use right after it comes off the 3D printer and is equipped with built-in gravity and touch sensors, which enable it to pick up, hold, and release objects.  “It’s the first time such a gripper can both grip and release. All you have to do is turn the gripper horizontally. This triggers a change in the airflow in the valves, making the two fingers of the gripper release," said a statement by the university.

The details regarding their research are published in the journal Science Robotics

A new 3D printing technique

Most 3D-printed soft robots are stiff; they have a lot of leaks when they come out of the printer; and they require a lot of processing and assembly after printing to be useable. Researchers were able to work their way around these problems by devising a new 3D printing method, which involves the printer nozzle tracing a continuous path through the entire pattern of each layer printed. “It’s like drawing a picture without ever lifting the pencil off the page,” said Michael T. Tolley, the senior author on the paper and an associate professor at the UC San Diego Jacobs School of Engineering, said in the statement.

This procedure lessens the possibility of leaks and faults in the printed object, which are prevalent when printing with soft materials. The new approach also enables the printing of thin walls as thin as 0.5 millimeters. Thinner walls and complicated, curved geometries allow for more deformation, resulting in a softer overall structure. "Researchers based the method on the Eulerian path, which in graph theory is a trail in a graph that touches every edge of that graph once and once only."

Following their new method, the team was able to print functional pneumatic soft robots with embedded control circuits consistently.

Practical applications

Soft robotics has the possibility of allowing robots to interact with humans and fragile things in a safe manner. According to the team, this gripper may be put on a robotic arm for industrial manufacturing, food processing, and fruit and vegetable handling. It may also be attached to a robot and used for study and exploration. It can also operate untethered, using merely a bottle of high-pressure gas as its power supply.

According to the team, the gripper's whole fabrication process needed no posttreatment, postassembly, or manufacturing fault rectification, making this technique very reproducible and accessible. "Our proposed approach represents a step toward complex, customized robotic systems, and components created at distributed fabricating facilities."

Study abstract

Most soft robots are pneumatically actuated and fabricated by molding and assembling processes that typically require many manual operations and limit complexity. Furthermore, complex control components (for example, electronic pumps and microcontrollers) must be added to achieve even simple functions. Desktop fused filament fabrication (FFF) three-dimensional printing provides an accessible alternative with less manual work and the capability of generating more complex structures. However, because of material and process limitations, FFF-printed soft robots often have a high effective stiffness and contain a large number of leaks, limiting their applications. We present an approach for the design and fabrication of soft, airtight pneumatic robotic devices using FFF to simultaneously print actuators with embedded fluidic control components. We demonstrated this approach by printing actuators an order of magnitude softer than those previously fabricated using FFF and capable of bending to form a complete circle. Similarly, we printed pneumatic valves that control a high-pressure airflow with low control pressure. Combining the actuators and valves, we demonstrated a monolithically printed electronics-free autonomous gripper. When connected to a constant supply of air pressure, the gripper autonomously detected and gripped an object and released the object when it detected a force due to the weight of the object acting perpendicular to the gripper. The entire fabrication process of the gripper required no posttreatment, postassembly, or repair of manufacturing defects, making this approach highly repeatable and accessible. Our proposed approach represents a step toward complex, customized robotic systems and components created at distributed fabricating facilities.

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