Periodic robust robotic rock chop via virtual model control

TL;DR

This paper presents a virtual model control scheme enabling robots to perform periodic, robust cutting motions like rock chopping without pre-planned paths, adapting to different tools and environments.

Contribution

Introduction of a virtual-model control method for robotic rock chopping that achieves stable, adaptive, and platform-independent cutting motions without prior environment knowledge.

Findings

Achieved sub-millimeter slicing accuracy.

Demonstrated robustness to tool and environment changes.

Enabled platform-independent, stable periodic cutting motions.

Abstract

Robotic cutting is a challenging contact-rich manipulation task where the robot must simultaneously negotiate unknown object mechanics, large contact forces, and precise motion requirements. We introduce a new active virtual-model control scheme that enables knife rocking motion for robot manipulators, without pre-planned trajectories or precise information of the environment. Motion is generated and controlled through switching virtual coupling with virtual mechanisms, given by virtual springs, dampers, and masses arranged in a suitable way. Through analysis and experiments, we demonstrate that the controlled robot behavior settles into a periodic motion. Experiments with a Franka manipulator demonstrate robust cuts with five different vegetables, and sub-millimeter slice accuracy from 1 mm to 6 mm at nearly one cut per second. The same controller survives changes in knife shape and cutting board height, and adaptation to a different humanoid manipulator, demonstrating robustness and platform independence.