Extrinsic Contact Sensing with Relative-Motion Tracking from Distributed Tactile Measurements
ICRA• 2021
Abstract
This paper addresses the localization of contacts of an unknown grasped rigid
object with its environment, i.e., extrinsic to the robot.
We explore the key role that distributed tactile sensing plays in localizing
contacts external to the robot, in contrast to the role that aggregated
force/torque measurements play in localizing contacts on the robot. When in
contact with the environment, an object will move in accordance with the
kinematic and possibly frictional constraints imposed by that contact. Small
motions of the object, which are observable with tactile sensors, indirectly
encode those constraints and the geometry that defines them.
We formulate the extrinsic contact sensing problem as a constraint-based
estimation. The estimation is subject to the kinematic constraints imposed by
the tactile measurements of object motion, as well as the kinematic (e.g.,
non-penetration) and possibly frictional (e.g., sticking) constraints imposed
by rigid-body mechanics.
We validate the approach in simulation and with real experiments on the case
studies of fixed point and line contacts.
This paper discusses the theoretical basis for the value of distributed
tactile sensing in contrast to aggregated force/torque measurements. It also
provides an estimation framework for localizing environmental contacts with
potential impact in contact-rich manipulation scenarios such as assembling or
packing.