Modular soft robots, which take inspiration from biological systems, combine the advantages of soft robots and modular robots. However, there is a lack of suitable methods for communication and sensing of them. A recent paper on arXiv.org proposes to use the acoustic signal for these tasks.
It gets inspiration from the use of acoustic signals among social insects, such as moths or crickets. The researchers suggest using surface-distributed acoustic modules that use piezoelectric transducers to send and receive acoustic waves. The modules are scalable, energy-efficient, and help to perform multiple robotic functions. They easily integrate with elastic skins of soft robots.
The modules take advantage of the membranes by enabling them to act as signal channels and state-dependent amplifiers/attenuators. The system allows robots to communicate by contact or at a distance or to sense external stimuli.
Modular soft robots combine the strengths of two traditionally separate areas of robotics. As modular robots, they can show robustness to individual failure and reconfigurability; as soft robots, they can deform and undergo large shape changes in order to adapt to their environment, and have inherent human safety. However, for sensing and communication these robots also combine the challenges of both: they require solutions that are scalable (low cost and complexity) and efficient (low power) to enable collectives of large numbers of robots, and these solutions must also be able to interface with the high extension ratio elastic bodies of soft robots. In this work, we seek to address these challenges using acoustic signals produced by piezoelectric surface transducers that are cheap, simple, and low power, and that not only integrate with but also leverage the elastic robot skins for signal transmission. Importantly, to further increase scalability, the transducers exhibit multi-functionality made possible by a relatively flat frequency response across the audible and ultrasonic ranges. With minimal hardware, they enable directional contact-based communication, audible-range communication at a distance, and exteroceptive sensing. We demonstrate a subset of the decentralized collective behaviors these functions make possible with multi-robot hardware implementations. The use of acoustic waves in this domain is shown to provide distinct advantages over existing solutions.
Research paper: Drew, D. S., Devlin, M., Hawkes, E., and Follmer, S., “Acoustic Communication and Sensing for Inflatable Modular Soft Robots”, 2021, arXiv:2101.11817. Link: https://arxiv.org/abs/2101.11817