Soft-Jig: A Flexible Sensing Jig for Simultaneously Fixing and Estimating Orientation of Assembly Parts

TL;DR

This paper introduces Soft-Jig, a versatile soft membrane-based sensing jig that can fix and estimate the orientation of assembly parts, reducing the need for custom rigid jigs.

Contribution

It presents a novel soft jig with embedded markers and a sensing method for simultaneous fixing and orientation estimation of parts.

Findings

Successfully estimated cylindrical part orientation with RMSE < 3 degrees

Demonstrated versatility for different shapes using soft membrane design

Achieved accurate pose estimation with simple optical sensing

Abstract

For assembly tasks, it is essential to firmly fix target parts and to accurately estimate their poses. Several rigid jigs for individual parts are frequently used in assembly factories to achieve precise and time-efficient product assembly. However, providing customized jigs is time-consuming. In this study, to address the lack of versatility in the shapes the jigs can be used for, we developed a flexible jig with a soft membrane including transparent beads and oil with a tuned refractive index. The bead-based jamming transition was accomplished by discharging only oil enabling a part to be firmly fixed. Because the two cameras under the jig are able to capture membrane shape changes, we proposed a sensing method to estimate the orientation of the part based on the behaviors of markers created on the jig's inner surface. Through estimation experiments, the proposed system could estimate the orientation of a cylindrical object with a diameter larger than 50 mm and an RMSE of less than 3 degrees.