A Bio-Inspired Distributed Optical Sensing Solution for Electrohydraulic Soft Continuum Robots

The shift from conventional rigid robots to soft robots is in part motivated by the desire for life-like motion. To further emulate natural systems, we desire tightly integrated distributed sensory networks, akin to those found in the animal kingdom. Borrowing inspiration from nature, we develop a two-part distributed optical sensing solution for a soft continuum robot comprised of hydraulically-amplified self-healing electrostatic actuators (HASELs). We analyze the accuracy and precision of the sensors and integrate them into a compact robotic platform to illustrate their compatability with HASEL actuators. We demonstrate their ability to estimate the pose of the robot end-effector during actuation with submillimeter accuracy. While other viable soft sensing options exist, many of them tend to either be incompatible with electrohydraulic systems or limit their speed, compliance, precision and overall performance. The optical sensing approach presented in this work provides a real-time accurate solution to state estimation of soft electrohydraulic robots.