A Soft and Inflatable Vision-Based Tactile Sensor for Inspection of Constrained and Confined Spaces

In this article, we present the design, fabrication, and characterization of a new class of tactile sensing called soft and inflatable vision-based tactile sensing (SI-VTS). SI-VTS benefits from a stretchable and inflatable torus-shaped balloon mechanism and flexible sensing module enabling unique features such as self-actuation, miniaturization, and conformability. Thanks to these features, SI-VTS can readily be integrated with the existing inspection devices/robots to enable the inspection of confined and constrained environments with complex geometries. Through conducting various experiments on two distinct types of SI-VTSs, we thoroughly characterized this class of sensors and analyzed the quality, sensitivity, and resolution of this class of tactile sensors (TSs) in interaction with eight different objects. Results demonstrated that SI-VTS can output high-quality and detailed textural images (with 53-
$\mu \text {m}$
resolution) at low interaction forces
$\geq 2.6$
N. We also successfully evaluated the conformability and self-actuation capability of SI-VTS by integrating the sensor with a colonoscope and performing various experiments inside a pipe connected with a 90° elbow.