eViper Wiggles Its Way to Energy-Efficient Locomotion — Matching a Mouse for Cost of Transportation
Flexible circuitry printed to a steel-bonded piezoelectric sheet gives this inchworm-like robot extreme energy efficiency.
A research team at Princeton University has designed a new platform for modular soft robots, eViper — showcasing a wiggling robot which can move long under a single watt of energy, delivering roughly the same efficiency of transportation as a living mouse.
"Future robotic systems need high energy efficiency," says Minjie Chen, assistant professor of electrical and computer engineering and one of the principal investigators on the project. "The eViper platform enables us to explore electrical, mechanical and power co-design to maximize the energy efficiency."
The extendable Vibrating Intelligent Piezo-Electric Robot (eViper) platform is designed to make use of the piezoelectric effect, converting electric power into mechanical movement as a series of carefully-timed pulses. With each pulse, the flexible body of the robot moves — first bending in one direction, then back in another. As the body flexes back and forth, the robot wiggles along the ground — and does so with, the team claims, an energy efficiency comparable to living land animals.
It doesn't matter how energy-efficient a robot is if you can't figure out where it's going to go, though — which is where the team's second breakthrough, SFERS, comes in. The Simulation Framework for Electroactive Robotic Sheet, which uses PyBullet physics simulation platform, provides a means of experimenting with different weight distributions and actuation patterns, allowing the team to predict the robot's movements and optimize its design for speed or minimum cost of transportation (COT).
The prototype eViper is built using a off-the-shelf flexible piezoelectric actuators bonded to steel foil, which the team says is highly scalable — though its prototype is on the smaller side, using just two actuators driven by a DFRobot Bluno Beetle microcontroller board. "The two-actuator eViper achieves a maximum speed of 3cm/s and a minimum COT of 36.4W/(kg·m²/s³). The weight of eViper is lower than most other robots," the researchers say, "[and] its COT is comparable to land animals (mice)."
The team's work has been presented at the IEEE International Conference on Intelligent Robots and Systems 2023 (IROS '23), and is available as an open-access preprint on Cornell's arXiv server; the SFERS software has been released under an unspecified open source license on GitHub.