Task-Specified Active Metrological Inspection with Measurement-Steered VLA Manipulation and Deterministic Evidence Gating
Organizations: University of Connecticut, Storrs, CT, USA · U.S. Army DEVCOM Ground Vehicle Systems Center (GVSC), Warren, MI, USA
Abstract
High-mix low-volume (HMLV) manufacturing requires inspection systems to adapt to changing parts, specifications, and work orders without repeated task-specific programming. Existing inspection automation typically assumes predefined sensing sequences, while general purpose robot agents optimize task completion rather than the completeness and validity of metrological evidence. We formulate task-specified active metrological inspection and propose From Requirements to Admissible Metrological Evidence (FRAME), a hierarchical dual-arm framework that converts an inspection instruction and structured specification into traceable conformance evidence. FRAME coordinates learned manipulation with calibrated laser profilometry: a task manager grounds and schedules requirements, active surface correspondence verifies physical-to-specification localization, and evidence memory tracks measurement provenance, admissibility, and coverage. Learned components may propose inspection targets and physical access actions, but deterministic datum-grounded measurement, admissibility checks, coverage auditing, and conformance evaluation prevent incomplete or unverified evidence from authorizing PASS. A series of physical experiments shows that FRAME achieves higher end-to-end inspection reliability, fewer false accepts, and shorter task completion time.
Figures & tables
| Task | Category | Industrial need | Required evidence |
|---|---|---|---|
| Specified feature | Verify a named feature after machining or printing | Measure required characteristic of the requested feature | |
| Anomaly detection | Protect mating, sealing, bearing, or datum surfaces | Measure damage and form error on the requested surface | |
| Relation or GD&T | Ensure alignment, interchangeability, and compatibility | Evaluate relations among features, surfaces, and datums | |
| Composite inspection | Inspect a declared feature group or interface | Aggregate all requirements in the declared group | |
| Functional goal | Verify an intent-level production goal | Infer the required scope and collect complete evidence |
| Method | Cand. acc. (%) | Wrong rel. / trial (%) | Abstain (%) | Rel. acc. (%) |
|---|---|---|---|---|
| L1 | ||||
| VLM w/o FRAME | 54.8 | 45.2 | - | - |
| VLM w/ FRAME | 92.9 | 2.4 | 9.5 | 97.4 |
| L2 | ||||
| VLM w/o FRAME | 52.4 | 47.6 | - | - |
| VLM w/ FRAME | 82.1 | 3.6 | 19.0 | 95.6 |
| Method | Correct-face acceptance | Wrong-face admission |
|---|---|---|
| w/o correspondence gate | 15/15 | 25/25 |
| w/ correspondence gate | 14/15 | 2/25 |
Robotic Inspection
Robotic inspection uses autonomous or remotely operated robots to examine infrastructure, equipment, and environments, detect defects, and document condition.
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