Ramus: A Frequency-Multiplexed Power Bus for Powering, Sensing and Controlling Robots

Yuki Nishizawa, Takuya Sasatani, Matthew Ishige, Yoshiaki Narusue, Takuya Umedachi, and Yoshihiro Kawahara

Abstract

As robots become more complex, small, and sophisticated, the cost and effort necessary for “wiring” become critical; the complex wiring makes the fabrication costly and necessitates care about space and stiffness of wires, which can inhibit the deformation of soft-bodied robots. The concept of power bus, which powers, controls, and monitors multiple slave modules (e.g., actuators, sensors) via a shared bus is one countermeasure for this challenge. However, handling many slave modules in real-time remains an unsolved issue; prior work suffers from a delay corresponding to the number of slaves or requires a rich signal processing unit in each slave module, which makes them unsuitable for controlling numerous actuators. To address this issue, we propose a frequency-multiplexed power bus, which integrates bandpass filters and load-modulation communication; our method enables us to power, control, and monitor all slave modules at once via a single pair of wires. Through analysis and experiments, we showed that eight nodes can be accommodated within a 9 MHz frequency band and can be independently controlled; finally, a caterpillar-like robot with four sensors and actuators was successfully driven by Ramus.

IEEE Robotics and Automation Letters

Published: July 2020

Volume: 5

Pages: 4126 - 4132