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Versioned, license-tagged source docs for the multi-layer GT knowledge base, ingested into the new core RAG collection bp_iace_safety_kb (whitelisted in the RAG search handler): - prism_risk_methodology.md — OPSS PRISM v2 (OGL v3): full severity(4)× probability(8) → risk-level matrix (Serious/High/Medium/Low), RAPEX-aligned. - cobot_biomech_limits.md — CC BY 4.0 papers (Behrens 2022 / Park 2019): force (N) & pressure (N/cm²) pain thresholds by body region (the data behind ISO/TS 15066, cited from the open papers — standard tables NOT reproduced). - hse_example_risk_assessments.md — HSE (OGL v3): qualitative hazard→control. - osha_robot_safety.md — OSHA OTM (public domain): 250 mm/s teach anchor, robot hazard taxonomy, safeguarding hierarchy. No DIN/EN/ISO/IEC/DGUV content reproduced; each doc states its license + attribution. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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Collaborative-robot biomechanical pain limits (force & pressure by body region)
Canonical, citable source document for the IACE cobot / power-and-force-limiting (PFL) severity anchors. The figures below are the experimental biomechanical pain-threshold data that underlie the ISO/TS 15066 collaborative-robot limits, taken only from open-access CC BY papers — not from the (copyrighted) ISO/TS 15066 tables themselves.
Source A — Force thresholds (Behrens et al. 2022, Frontiers, CC BY 4.0)
- Source: Behrens R, Pliske G, Umbreit M, Piatek S, Walcher F, Elkmann N
- Doc: A Statistical Model to Determine Biomechanical Limits for Physically Safe Interactions With Collaborative Robots
- Journal: Frontiers in Robotics and AI, vol. 8, art. 667818 (2022)
- License: CC BY 4.0 (Frontiers open access — reuse with attribution)
- Attribution:
Behrens et al. (2022), Front. Robot. AI 8:667818, CC BY 4.0 - Retrieved: 2026-06 · DOI: https://doi.org/10.3389/frobt.2021.667818
- Study: 112 subjects, emulated impact (transient) and pinching (quasi-static) loads at 28 body locations; force raised until slightly painful.
Force pain thresholds by body region (N)
Values are the 75th-percentile limits for a mixed-gender group (≈70% male), blunt contact, from the paper's results. Pinching ≈ quasi-static contact; Impact ≈ transient contact — transient limits are higher (≈1.5–2×).
| Body region | Pinching / quasi-static (N) | Impact / transient (N) |
|---|---|---|
| Forehead | 110 | 150 |
| Temple | 60 | 90 |
| Masticatory muscle | 40 | 70 |
| Neck muscle | 70 | 110 |
| C7 vertebra | 50 | 70 |
| Shoulder joint | 60 | 100 |
| L5 vertebra | 110 | 180 |
| Sternum | 80 | 110 |
| Pectoral muscle | 60 | 110 |
| Abdominal muscle | 60 | 90 |
| Pelvic bone | 90 | 140 |
| Deltoid muscle | 100 | 110 |
| Humerus | 70 | 150 |
| Radial bone | 100 | 180 |
| Forearm muscle | 100 | 170 |
| Arm nerve | 80 | 140 |
| Forefinger pad | 150 | 390 |
| Forefinger DIP joint | 160 | 370 |
| Thenar eminence | 120 | 260 |
| Palm | 150 | 330 |
| Back of hand | 150 | 250 |
| Thigh muscle | 140 | 200 |
| Kneecap | 160 | 270 |
| Middle of shin | 150 | 260 |
| Calf muscle | 130 | 260 |
Lowest-tolerance regions: face (masticatory muscle, temple) and neck (C7, shoulder joint) — these dominate worst-case severity for a head/neck contact.
Source B — Pressure thresholds (Park et al. 2019, PLOS ONE, CC BY 4.0)
- Source: Park MY, Han D, Lim JH, Shin MK, Han YR, Kim DH, Rhim S, Kim KS
- Doc: Assessment of pressure pain thresholds in collisions with collaborative robots
- Journal: PLOS ONE 14(5): e0215890 (2019)
- License: CC BY 4.0 (PLOS open access — reuse with attribution)
- Attribution:
Park et al. (2019), PLOS ONE 14(5):e0215890, CC BY 4.0 - Retrieved: 2026-06 · DOI: https://doi.org/10.1371/journal.pone.0215890
Pressure pain thresholds by body region (N/cm²)
Overall measured range across body sites: 65.1 ± 22.6 to 196.1 ± 85.8 N/cm². Younger subjects showed 3–33% lower thresholds; BMI effect minimal at most sites.
| Body region | Pressure pain threshold (N/cm²) |
|---|---|
| Arm nerve | 65.1 ± 22.6 (lowest) |
| Shoulder joint | ≈ 87 |
| Neck muscle / forehead / ball of thumb / shin | ≈ 100–120 |
| Index finger pad / palm of hand | > 160 |
| Back of hand | 196.1 ± 85.8 (highest) |
How these are used in IACE
- Severity anchor for cobot/PFL hazards: force (N) and pressure (N/cm²) thresholds per body region set the IACE S (severity) tier for a power-and-force-limited contact — a contact below the regional limit is tolerable, above it is an injury-relevant exposure.
- Transient vs quasi-static: the two force columns let IACE distinguish transient (impact) from quasi-static (clamping/pinching) contact, matching the two ISO/TS 15066 contact regimes without reproducing the standard's tables.
- Worst-case body region: the lowest-threshold regions (face, neck) drive the conservative default when the contact body region is unknown.
Licensing note: the ISO/TS 15066 limit tables are not reproduced. All numeric values above are taken from the two CC BY 4.0 academic papers cited and are attributed to those papers. No DGUV/IFA or Beuth/ISO table is used.