Summary: Researchers have developed a new method to allow robots to move more like real limbs.
Tool makes it easier to design robots that can bend and twist.
Designing a soft robot to move organically — to bend like a finger or twist like a wrist — has always been a process of trial and error. Now, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering have developed a method to automatically design soft actuators based on the desired movement.
The research is published in The Proceedings of the National Academy of Sciences.
“Rather than designing these actuators empirically, we wanted a tool where you could plug in a motion and it would tell you how to design the actuator to achieve that motion,” said Katia Bertoldi, the John L. Loeb Associate Professor of the Natural Sciences and coauthor of the paper.
Designing a soft robot that can bend like a finger or knee may seem simple but the motion is actually incredibly complex.
“The design is so complicated because one actuator type is not enough to produce complex motions,” said Fionnuala Connolly, a graduate student at SEAS and first author of the paper. “You need a sequence of actuator segments, each performing a different motion and you want to actuate them using a single input.”
The method developed by the team uses mathematical modeling of fluid-powered, fiber-reinforced actuators to optimize the design of an actuator to perform a certain motion. The team used this model to design a soft robot that bends like an index finger and twists like a thumb when powered by a single pressure source.
“This research streamlines the process of designing soft robots that can perform complex movements,” said Conor Walsh, the John L. Loeb Associate Professor of Engineering and Applied Sciences, Core Faculty Member at the Wyss Institute for Biologically Inspired Engineering and coauthor of the paper. “It can be used to design a robot arm that moves along a certain path or a wearable robot that assists with motion of a limb.”
The new methodology will be included in the Soft Robotic Toolkit, an online, open-source resource developed at SEAS to assist researchers, educators and budding innovators to design, fabrication, model, characterize and control their own soft robots.
Source: Leah Burrows – Harvard
Image Source: NeuroscienceNews.com images are credited to Harvard SEAS.
Original Research: Abstract for “Automatic design of fiber-reinforced soft actuators for trajectory matching” by Fionnuala Connolly, Conor J. Walsh, and Katia Bertoldi in PNAS. Published online December 19 2016 doi:10.1073/pnas.1615140114
Automatic design of fiber-reinforced soft actuators for trajectory matching
Soft actuators are the components responsible for producing motion in soft robots. Although soft actuators have allowed for a variety of innovative applications, there is a need for design tools that can help to efficiently and systematically design actuators for particular functions. Mathematical modeling of soft actuators is an area that is still in its infancy but has the potential to provide quantitative insights into the response of the actuators. These insights can be used to guide actuator design, thus accelerating the design process. Here, we study fluid-powered fiber-reinforced actuators, because these have previously been shown to be capable of producing a wide range of motions. We present a design strategy that takes a kinematic trajectory as its input and uses analytical modeling based on nonlinear elasticity and optimization to identify the optimal design parameters for an actuator that will follow this trajectory upon pressurization. We experimentally verify our modeling approach, and finally we demonstrate how the strategy works, by designing actuators that replicate the motion of the index finger and thumb.
“Automatic design of fiber-reinforced soft actuators for trajectory matching” by Fionnuala Connolly, Conor J. Walsh, and Katia Bertoldi in PNAS. Published online December 19 2016 doi:10.1073/pnas.1615140114