High Precision Hydraulic Excavator Control for Heavy-Duty Grading

TL;DR

This paper introduces an autonomous hydraulic excavator controller that achieves high-precision grading across different hydraulic architectures, outperforming commercial solutions in accuracy and efficiency.

Contribution

A versatile, hydraulic-aware control method applicable to various excavator types, combining low-level hydraulic-specific control with high-level path tracking.

Findings

Achieves RMSE of 1.8 cm, outperforming the commercial solution with 4.7 cm RMSE.

Applicable to load-sensing and negative flow control machines through calibration.

Improves machine usage by leveraging maximum function pressure, avoiding premature stalls.

Abstract

High-precision heavy-duty grading is a common step in earthworks, traditionally carried out manually by skilled operators. Removing a significant amount of material while achieving a high-precision surface requires substantial machine-specific experience. Different hydraulic architectures react differently to operator inputs and soil interaction forces, which makes generalizable controllers challenging. In this paper, we present an autonomous controller that achieves high-precision grading at expert-operator speed on Load Sensing and Negative Flow Control machines alike. We split our controller into two parts: (1) a hydraulic-aware low-level loop that is hydraulic architecture-specific and (2) a path-tracking layer that coordinates joint motions and responses. Through a calibration process, our technique is applicable to load-sensing and negative-flow-control machinery. To showcase its versatility, we benchmark our approach on two excavators with different hydraulics and compare it against a commercial state-of-the-art solution. Our technique (RMSE 1.8~cm) outperforms the commercial solution (RMSE 4.7~cm) in precision by a factor of 2.6 and improves machine usage by leveraging the maximum function pressure, as opposed to commercial solutions that stall prematurely.