Autonomous Excavation of Challenging Terrain using Oscillatory Primitives and Adaptive Impedance Control

TL;DR

This paper introduces a novel autonomous excavation method using oscillatory motions inspired by humans and an adaptive impedance controller to improve performance on challenging terrains prone to jamming.

Contribution

It presents a new oscillatory primitive-based excavation strategy combined with RAIC, an adaptive impedance control method, to enhance autonomous excavation in difficult terrains.

Findings

Improved volume scooped across terrains

Reduced jamming and protective stop rate

Higher trajectory completion percentage

Abstract

This paper addresses the challenge of autonomous excavation of challenging terrains, in particular those that are prone to jamming and inter-particle adhesion when tackled by a standard penetrate-drag-scoop motion pattern. Inspired by human excavation strategies, our approach incorporates oscillatory rotation elements -- including swivel, twist, and dive motions -- to break up compacted, tangled grains and reduce jamming. We also present an adaptive impedance control method, the Reactive Attractor Impedance Controller (RAIC), that adapts a motion trajectory to unexpected forces during loading in a manner that tracks a trajectory closely when loads are low, but avoids excessive loads when significant resistance is met. Our method is evaluated on four terrains using a robotic arm, demonstrating improved excavation performance across multiple metrics, including volume scooped, protective stop rate, and trajectory completion percentage.