Towards footwear manufacturing 4.0: shoe sole robotic grasping in assembling operations

In this paper, we present a robotic workcell for task automation in footwear manufacturing such as sole digitization, glue
dispensing, and sole manipulation from different places within the factory plant. We aim to make progress towards shoe
industry 4.0. To achieve it, we have implemented a novel sole grasping method, compatible with soles of different shapes,
sizes, and materials, by exploiting the particular characteristics of these objects. Our proposal is able to work well with low
density point clouds from a single RGBD camera and also with dense point clouds obtained from a laser scanner digitizer.
The method computes antipodal grasping points from visual data in both cases and it does not require a previous recognition
of sole. It relies on sole contour extraction using concave hulls and measuring the curvature on contour areas. Our method
was tested both in a simulated environment and in real conditions of manufacturing at INESCOP facilities, processing 20
soles with different sizes and characteristics. Grasps were performed in two different configurations, obtaining an average
score of 97.5% of successful real grasps for soles without heel made with materials of low or medium flexibility. In both
cases, the grasping method was tested without carrying out tactile control throughout the task.