Rapid manufacturing of color-based hemispherical soft tactile fingertips

TL;DR

This paper introduces a rapid, cost-effective manufacturing method for high-resolution, color-based hemispherical tactile fingertips that accurately measure 3D deformation fields for improved tactile sensing in manipulation tasks.

Contribution

A novel multi-color additive manufacturing process for creating dense, marker-based soft tactile sensors capable of high-resolution deformation measurement.

Findings

Achieved a marker density of 400 markers on a 21 mm radius hemisphere.

Threefold increase in curvature measurement accuracy compared to previous methods.

Demonstrated effective tactile sensing for object contact analysis.

Abstract

Tactile sensing can provide access to information about the contact (i.e. slippage, surface feature, friction), which is out of reach of vision but crucial for manipulation. To access this information, a dense measurement of the deformation of soft fingertips is necessary. Recently, tactile sensors that rely on a camera looking at a deformable membrane have demonstrated that a dense measurement of the contact is possible. However, their manufacturing can be time-consuming and labor-intensive. Here, we show a new design method that uses multi-color additive manufacturing and silicone casting to efficiently manufacture soft marker-based tactile sensors that are able to capture with high-resolution the three-dimensional deformation field at the interface. Each marker is composed of two superimposed color filters. The subtractive color mixing encodes the normal deformation of the membrane, and the lateral deformation is found by centroid detection. With this manufacturing method, we can reach a density of 400 markers on a 21 mm radius hemisphere, allowing for regular and dense measurement of the deformation. We calibrated and validated the approach by finding the curvature of objects with a threefold increase in accuracy as compared to previous implementations. The results demonstrate a simple yet effective approach to manufacturing artificial fingertips for capturing a rich image of the tactile interaction at the location of contact.