Robotic Materials

Identification and Control of a Nonlinear Soft Actuator and Sensor System

2020

Article

rm

Soft robots are becoming increasingly prevalent, with unique applications to medical devices and wearable technology. Understanding the dynamics of nonlinear soft actuators is crucial to creating controllable soft robots. this letter presents a system identification process and closed-loop control of foldable HASEL (hydraulically amplified self-healing electrostatic) soft actuators. We characterized foldable HASELs with linear frequency response tests and modeled them using a linear superposition of static and dynamic terms. We also identified two responses of the system: an activation and relaxation response. Based on these two responses, we developed a dual-mode controller which was validated through closed-loop control using a capacitive elastomeric strain sensor wrapped around the actuator. Using this integrated sensor, we achieved step response rise times as fast as 0.025 s and settling times as fast as 0.17 s while under load. These system identification and control techniques can be applied to any HASEL-driven soft robot and could be applied to other soft actuators to enable controllable soft robots.

Author(s): Brian K. Johnson and Vani Sundaram and Mantas Naris and Eric Acome and Khoi Ly and Nikolaus Correll and Christoph Keplinger and James Sean Humbert and Mark E. Rentschler
Journal: IEEE Robotics and Automation Letters
Volume: 5
Number (issue): 3
Pages: 3783--3790
Year: 2020
Month: March
Department(s): Robotic Materials
Bibtex Type: Article (article)
Paper Type: Journal
DOI: 10.1109/LRA.2020.2982056
URL: https://ieeexplore.ieee.org/abstract/document/9042285
Additional (custom) Fields:
acknowledgment: The authors would like to acknowledge Ellen Rumley for her contributions towards understanding the effects of charge retention when using the polyester lidding film (L0WS, Multiplastics).

BibTex 

@article{Keplinger20-IEEE-Identification,
  title = {Identification and Control of a Nonlinear Soft Actuator and Sensor System},
  author = {Johnson, Brian K. and Sundaram, Vani and Naris, Mantas and Acome, Eric and Ly, Khoi and Correll, Nikolaus and Keplinger, Christoph and Humbert, James Sean and Rentschler, Mark E.},
  journal = {IEEE Robotics and Automation Letters},
  volume = {5},
  number = {3},
  pages = {3783--3790},
  month = mar,
  year = {2020},
  doi = {10.1109/LRA.2020.2982056},
  url = {https://ieeexplore.ieee.org/abstract/document/9042285},
  month_numeric = {3}
}