Soft Robotic Sensing, Proprioception via Cable and Microfluidic Transmission

Abstract

Current challenges in soft robotics include sensing and state awareness. Modern soft robotic systems require many more sensors than traditional robots to estimate pose and contact forces. Existing soft sensors include resistive, conductive, optical, and capacitive sensing, with each sensor requiring electronic circuitry and connection to a dedicated line to a data acquisition system, creating a rapidly increasing burden as the number of sensors increases. We demonstrate a network of fiber-based displacement sensors to measure robot state (bend, twist, elongation) and two microfluidic pressure sensors to measure overall and local pressures. These passive sensors transmit information from a soft robot to a nearby display assembly, where a digital camera records displacement and pressure data. We present a configuration in which one camera tracks 11 sensors consisting of nine fiber-based displacement sensors and two microfluidic pressure sensors, eliminating the need for an array of electronic sensors throughout the robot. Finally, we present a Cephalopod-chromatophore-inspired color cell pressure sensor. While these techniques can be used in a variety of soft robot devices, we present fiber and fluid sensing on an elastomeric finger. These techniques are widely suitable for state estimation in the soft robotics field and will allow future progress toward robust, low-cost, real-time control of soft robots. This increased state awareness is necessary for robots to interact with humans, potentially the greatest benefit of the emerging soft robotics field.

Recent Advances in Perceptive Intelligence for Soft Robotics

“…Reproduced with permission. [ 72 ] Copyright 2021, MDPI. d) Hydrogel resistive sensor in pneumatic actuator sensing twisting.…”

“…Microfluidic methods realize the twisting sensing for soft robots by embedding the microfluidic sensor network, which is applied to decouple twisting from other motion states (disturbances). For example, Lin et al [ 72 ] developed an embedded fiber‐based microfluidic displacement sensor network based on a similar high‐density sensor design for measuring the torsional state of the robot (Figure 3c). Flexible but nonstretchable/noncompressible nylon fibers are placed in air‐filled microchannels with flexible elastic fingers.…”

“…c) Microfluidic displacement sensors to measure the twisting state of the robot. Reproduced with permission [72]. Copyright 2021, MDPI.…”

Research on Posture Sensing and Error Elimination for Soft Manipulator Using FBG Sensors

“…Owing to advantages in aspects such as flexibility, safety, and comfort, soft robots have shown to be highly promising in clinical medicine [1][2][3]. With high degrees of freedom and a flexible structure, soft robots provide new ideas and directions for resolving the bottleneck problems of clinical operations [4,5].…”