Soft Robotic Sensing, Proprioception via Cable and Microfluidic Transmission

Keng-Yu Lin,Arturo Gamboa-Gonzalez,Michael Wehner

doi:10.3390/electronics10243166

Keng-Yu Lin, Arturo Gamboa-Gonzalez + Show 1 more

Open Access

https://doi.org/10.3390/electronics10243166

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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.

Highlights

Soft robots have shown an increasing potential to dramatically expand the capabilities of the field of robotics
For soft robots to emerge into humanpopulated environments and to perform useful real-world tasks, advances are required in sensors able to quickly provide robust state information, both as individual sensors and as integrated sensing systems
We present the technique’s ability to quantify overall pressure via an integrated microfluidic sensor (Figure 1D) and local contact pressure via a surface-mounted microfluidic sensor (Figure 1E). These sensors can be designed into soft robotic actuators, and leverage the framework provided from beam theory and classical mechanics of materials to sense the state of each actuated unit

Summary

Introduction

Soft robots have shown an increasing potential to dramatically expand the capabilities of the field of robotics. There has been work in optical methods including the SOFTcell project by Bajcsy and Fearing [21] in which tactile response was determined through optical analysis of a deformed membrane, and video tracking of markers adhered to or embedded in soft components [5] While these studies present compelling sensors, further development is necessary in utilizing a suite of sensors to increase overall state awareness. We present the technique’s ability to quantify overall pressure via an integrated microfluidic sensor (Figure 1D) and local contact pressure via a surface-mounted microfluidic sensor (Figure 1E) These sensors ( designed to be used in groups) can be designed into soft robotic actuators, and leverage the framework provided from beam theory and classical mechanics of materials to sense the state of each actuated unit. External force causes the cell to change shape from spherical to a disk shape, changing disk diameter

Method

Design and Fabrication

Vision Algorithms

Sensor Characterization

Discussion