A team of UCLA engineers and their colleagues have developed a new design strategy and 3D printing technique to build robots in one step.
A study describing the advancement, as well as the construction and demonstration of an assortment of tiny robots that walk, maneuver and jump, has been published in Science.
This breakthrough allowed all of the mechanical and electronic systems necessary for the operation of a robot to be manufactured in one go by a new type of 3D printing process for technical active materials with multiple functions (also called metamaterials). ). Once printed in 3D, a “meta-bot” will be capable of propulsion, movement, sensing and decision-making.
Printed metamaterials consist of an internal network of sensory, mobile, and structural elements and can move on their own by following programmed commands. With the internal motion and sensing network already in place, the only external component needed is a small battery to power the robot.
“We anticipate that this methodology for designing and printing smart robotic materials will help realize a class of self-contained materials that could replace the current complex assembly process to make a robot,” said the study’s lead researcher, Xiaoyu (Rayne) Zheng, associate professor of civil and environmental engineering, and mechanical and aerospace engineering at the UCLA Samueli School of Engineering. “With complex movements, multiple sensing modes, and programmable decision-making capabilities, all tightly integrated, it resembles a biological system in which nerves, bones, and tendons work in tandem to execute controlled movements.”
The team demonstrated integration with an on-board battery and controller for fully autonomous operation of the 3D-printed robots, each the size of a fingernail. According to Zheng, who is also a fellow at UCLA’s California NanoSystems Institute, the methodology could lead to new designs for biomedical robots, such as self-guided endoscopes or tiny swimming robots, which can emit ultrasound and move near blood vessels to deliver drug doses to specific target sites within the body.
These “meta-bots” can also explore dangerous environments. In a collapsed building, for example, a swarm of these tiny robots armed with built-in sensing parts could quickly access confined spaces, assess threat levels and aid rescue efforts by finding people trapped in the rubble.
Most robots, regardless of size, are usually built in a series of complex manufacturing steps that integrate limbs, electronics and active components. The process results in heavier weights, larger volumes, and reduced output force compared to robots that could be built using this new method.
The key to the UCLA-led all-in-one method is the design and printing of piezoelectric metamaterials – a class of complex lattice materials that can change shape and move in response to an electric field. Where create an electrical charge as a result of physical forces.
The use of active materials capable of translating electricity into movements is not new. However, these materials generally have limitations in their range of motion and travel distance. They must also be connected to gearbox type transmission systems in order to achieve the desired movements.
In contrast, the robotic materials developed by UCLA – each the size of a penny – are composed of complex piezoelectric and structural elements designed to bend, bend, twist, rotate, expand or contract at large speed.
The team also presented a methodology for designing these robotic materials so that users can create their own models and print the materials directly in a robot.
“This allows the actuation elements to be precisely arranged throughout the robot for rapid, complex and extended movements over different types of terrain,” said study lead author Huachen Cui, a postdoctoral researcher at UCLA at the Zheng Additive Manufacturing and Metamaterials Lab. “Thanks to the bidirectional piezoelectric effect, robotic materials can also sense their contortions themselves, detect obstacles via echoes and ultrasonic emissions, as well as respond to external stimuli via a feedback control loop that determines how robots move, how fast they move, and what target they move to.”
Using this technique, the team built and demonstrated three “meta-bots” with different abilities. One robot can navigate around S-shaped corners and randomly placed obstacles, another can escape in response to contact impact, while the third robot can walk over rough terrain and even do small jumps.
The other authors of the UCLA study are graduate students Desheng Yao, Ryan Hensleigh, Zhenpeng Xu and Haotian Lu; postdoctoral researcher Ariel Calderon; development engineering associate Zhen Wang. The other authors are Sheyda Davaria, research associate at Virginia Tech; Patrick Mercier, associate professor of electrical and computer engineering at UC San Diego; and Pablo Tarazaga, professor of mechanical engineering at Texas A&M University.
The research was supported by a Young Faculty Award and a Director’s Fellowship Award from the US Defense Advanced Research Projects Agency (DARPA), with additional funding from the US Office of Naval Research, Air Force Office of Scientific Research and the National Science Foundation.
The advance incorporates 3D printing techniques previously developed by Zheng and Hensleigh when they were both researchers at Virginia Tech, which holds the patent. The researchers plan to file an additional patent through UCLA’s Technology Development Group for the new methodology developed at UCLA.