Voronoi Features for Tactile Sensing: Direct Inference of Pressure, Shear, and Contact Locations

There are a wide range of features that tactile contact provides, each with different aspects of information that can be used for object grasping, manipulation, and perception. In this paper inference of some key tactile features, tip displacement, contact location, shear direction and magnitude, is demonstrated by introducing a novel method of transducing a third dimension to the sensor data via Voronoi tessellation. The inferred features are displayed throughout the work in a new visualisation mode derived from the Voronoi tessellation; these visualisations create easier interpretation of data from an optical tactile sensor that measures local shear from displacement of internal pins (the TacTip). The output values of tip displacement and shear magnitude are calibrated to appropriate mechanical units and validate the direction of shear inferred from the sensor. We show that these methods can infer the direction of shear to $\sim$2.3$^{\circ}$ without the need for training a classifier or regressor. The approach demonstrated here will increase the versatility and generality of the sensors and thus allow sensor to be used in more unstructured and unknown environments, as well as improve the use of these tactile sensors in more complex systems such as robot hands.Comment: Presented at ICRA 201

A framework for representing interaction tasks based on tactile data

This paper describes a framework for representing physical interaction tasks using tactile feedback. Although contact feedback has been widely exploited to control interaction with objects, the direct use of tactile information in designing and representing physical interaction rules has not received comparable attention in the literature. The missing link between algorithms implementing models of interaction and frameworks providing tactile information is one of the possible reasons. The major contribution of the paper is a working method to build a map of tactile sensors attached to a robot body and a control law using such a map to tune physical interaction with an external object. Experiments are used to validate the approach