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

Examples of wiring to the caterpillar-like robot, which has four actuators and four sensors. (a) Example of typical wiring. A Wire is required for each actuator/sensor. (b) Our proposed method, Ramus. Only two wires are required to connect all actuators/sensors; by utilizing frequency-multiplexing, we can selectively power actuators/sensors and also acquire sensor values simultaneously.

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.

Publications

  1. Yuki Nishizawa, Takuya Sasatani, Matthew Ishige, Yoshiaki Narusue, Takuya Umedachi, Yoshihiro Kawahara, “Ramus: A Frequency-Multiplexed Power Bus for Powering, Sensing and Controlling Robots,”IEEE Robotics and Automation Letters (Proc. of the 3rd IEEE International Conference on Soft Robotics – RoboSoft 2020), vol. 5 , Issue. 3, pp. 4126 - 4132, July 2020.

  2. 西澤勇輝,成末義哲,笹谷拓也,川原圭博,“Ramus: 周波数選択性電力バスによる多数アクチュエータの独立駆動システムの検討,” 電子情報通信学会 ソサイエティ大会,A-1-6,Sept. 2018.