Excavator motion control system ensures operator-approved actions only
From LLM Plans to Authorized Motion: Execution-Bound Authorization for Excavators
Robotics
Summary
Sometimes, machines like excavators can move in ways that their human operators didn't approve or expect. To fix this, the authors propose a system that ties each allowed movement to a special authorization that expires after use. This system constantly checks if the machine's motions still match what the operator approved and can stop the machine safely if needed. They tested this approach with lots of simulated digging scenarios and showed that unauthorized or unsafe movements were prevented effectively.
What this means in practice
- •For construction equipment developers: Enable excavators to execute only operator-approved motions, improving safety during autonomous or semi-autonomous digging tasks.
- •For industrial automation engineers: Integrate motion-bound authorization techniques to supervise and safely interrupt hydraulic machinery based on real-time authority verification.
Authors
Mehdi Heydari Shahna, Seihun Kim, Soyi Jung, Soohyun Park, Jouni Mattila, Joongheon Kim
Abstract
An LLM-directed excavator can execute mechanically feasible motion whose destination or authority no longer matches the operator's approval. We propose execution-bound authorization for the approval--dispatch--execution interval. A one-use lease binds the action, generated motion, mission contract and admission tolerance; atomic dispatch rechecks current authority and measured joint drift. Periodic supervision detects revocation and requests a quintic stop with a carry-pitch endpoint, selected through sampled joint, stroke, flow and reference-acceleration checks. The framework connects exact motion identity to dispatch integrity and load-aware interruption. Evaluation combines a 672-case interface suite, four loaded digging cases in synchronous simulation, unloaded MuJoCo/Pinocchio transfers and two command-level LLM planners. The gateway admitted all 120 benign interface cases and produced zero unauthorized dispatches in the attack suite. Loaded dispatch-window tests produced zero unauthorized deposition. During simulated dump-phase revocation, maximum closed-site deposition decreased from 1.23 to 0.33\,m$^3$; loaded-slew stops used less than 75\% of nominal swing torque. These results demonstrate motion-bound authorization and quantify the retention and stopping behavior of supervised excavation skills.