Physical-Touch Observability from Wrist Wrench in Granular Scooping

Hongyi Lin; Song Zhang; Xubo Liu; Yang Liu

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arXiv · 2609.22852

Physical-Touch Observability from Wrist Wrench in Granular Scooping

Hongyi Lin·Song Zhang·Xubo Liu·Yang Liu

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Abstract

Mining and earthmoving are important real-world deployment settings for embodied intelligence. Autonomous transport and driving systems have improved substantially, but loading and scooping still often depend on skilled human operators, exposing personnel and equipment to operational risk. For robotic scooping, pre-contact RGB-D sensing reveals surface geometry but not the resistance, compaction, tool engagement, or load transfer that emerge during interaction. We test whether the current scoop's six-axis wrist force/torque (F/T), or wrist wrench, contains information about final collected volume, and whether that information depends on the correctly paired action-terrain interaction. We call this property physical-touch observability. Using 6,700 real-robot scoops across 67 terrains, we evaluate correctly paired current-scoop F/T against pre-contact prediction and correspondence-breaking controls under terrain-held-out testing. At the retrospective 60% sequence boundary, correctly paired F/T reduces mean absolute error by 14.2% relative to Action-only and by 21.9% relative to cross-terrain mismatched F/T. Engineered signal summaries reproduce the result across model architectures. Together, these findings position wrist wrench not merely as a low-level feedback signal, but as a task-level perceptual modality through which embodied robots can infer hidden physical states during interaction, providing a foundation for response-aware autonomy in mining and other contact-rich tasks.

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BibTeX RIS

Hongyi Lin, Song Zhang, Xubo Liu, Yang Liu. 2026-09-19. Physical-Touch Observability from Wrist Wrench in Granular Scooping. https://arxiv.org/abs/2609.22852

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