Hartshorn et al. 2022 — Feasibility of UAS-based EMI / LCS for underground utilities¶
| Field | Value |
|---|---|
| Record ID | EVID-0013 |
| Type | evidence |
| Title | Hartshorn et al. 2022 — Feasibility of UAS-based EMI / LCS for underground utilities |
| Status | reviewed |
| Confidence | high |
| Updated | 2026-09-09 |
| Source URL | https://doi.org/10.3390/rs14163973 |
| Topics | electromagnetic, uav_operations, standoff_altitude, underground_utility_detection |
| Archived source | retained internally |
Citation¶
Hartshorn, C. A., S. D. Isaacson, B. E. Barrowes, L. J. Perren, D. Lozano, and F. Shubitidze. 2022. Analysis of the Feasibility of UAS-Based EMI Sensing for Underground Utilities Detection and Mapping. Remote Sensing 14(16): 3973. https://doi.org/10.3390/rs14163973
OSTI record: https://www.osti.gov/biblio/1981183
Source¶
Open-access article. MDPI PDF endpoint returned HTTP 403; local PDF from Semantic Scholar. Text extract stored next to the PDF.
Why This Source Matters¶
Named-technology follow-up for ESTCP EW25-8806 LCS. It is the primary public paper that reports EMI standoff physics for long conductors, a speculated UAS hover height, and an explicit statement that urban/wooded sites are a poor UAS fit.
Source-Faithful Summary¶
The authors describe Linear Current Sensing (LCS): wide-band EMI (50 kHz to 2 MHz) with a triaxial magnetic-field gradiometer. Long conductors support linear currents whose secondary field decays as 1/R², versus 1/R⁶ for compact metallic targets, which they say allows detection at 10 m or more. Hardware was integrated on a Harris Aerial HX8 (payload ~8 kg). The LCS sensor (~14 lb) is suspended on 12-ft tethers to reduce UAS motor noise. A plywood/foam mock payload was used to test hover and maneuverability at 10, 12.5, and 15 lb. From that test they speculate that under ideal flat terrain they could fly at about 1.5 m standoff, with more conservative (larger) standoff as sites become complex. Numerical STR (signal-to-transmitter ratio) for a 1 m deep, 100 m long wire at 100 kHz in 1 mS/m soil showed 1 m, 2 m, and 4 m sensor heights above ground meeting their “easy detection” (>20 dB) criterion; 8 m did not, though it remained in the 10–20 dB “feasible” band. Pipe detections in the paper are from hand-carried gradiometer surveys, not from a flown LCS map of a service line.
Relevant Facts¶
- Geometry: paper defines standoff as sensor height above ground. Burial is stated separately (1 m in the STR models; some field wires 6–8 m).
- Compact EMI vs LCS: 1/R⁶ vs 1/R² decay.
- UAS: HX8, ~8 kg payload; sensor ~14 lb; 12-ft tethers; 30 min sensor battery.
- Hover test: mock platform, not a buried-pipe UAV survey.
- Speculated flight standoff: ~1.5 m in ideal flat terrain; larger as complexity increases.
- Urban/wooded: authors say UAS is not well suited; hand-carried or UGV may be more appropriate.
- Field pipe data: carried sensor over a utility pipe in concrete; AM radio used as a passive source in one case.
- Not lead vs copper classification. Not Edison. Not GPR.
Quantitative Data¶
| Variable | Value | Units | Conditions | Source Location |
|---|---|---|---|---|
| Claimed LCS detection distance (abstract) | ≥10 | m | long conductors; 1/R² decay | Abstract |
| Sensor–UAS tether length | 12 | ft | noise mitigation | §1 / hardware |
| Sensor mass | ~14 | lb | LCS payload | §1 |
| UAS payload capacity | ~8 | kg | Harris HX8 | §1 |
| Speculated UAS standoff (flat terrain) | ~1.5 | m | mock hover test; speculation | p. 4 |
| STR model burial | 1 | m | 100 m wire, 100 kHz, 1 mS/m soil | §5 |
| STR model sensor height | 1, 2, 4, 8 | m | height above ground; burial fixed at 1 m | Figs. 19–20 |
| STR “easy” threshold (as used) | 20 | dB | authors; cite [13] | §5 |
| STR “feasible” threshold (as used) | 10 | dB | authors; cite [13] | §5 |
| Heights meeting >20 dB (gradiometer |ΔHy|) | 1, 2, 4 | m | modeled, not flown | Fig. 20 |
| Height not meeting >20 dB | 8 | m | still 10–20 dB | Fig. 20 |
What This Source Supports¶
- LCS-class EMI for long metallic conductors can remain detectable at meter-scale AGL in models, unlike compact-object EMI.
- UAS integration is a platform/hover demonstration plus models, not a published UAV LSL survey.
- Dense/urban sites are called out by the authors as a poor UAS environment.
What This Source Does NOT Establish¶
- No UAV-collected pipe map with localization error or Pd.
- No lead vs copper vs galvanized ID.
- 1.5 m is speculated from mock hover, not a measured sensing altitude.
- STR curves are modeled for a long wire, not a ¾-inch lead service line.
- 10 m “or more” is a decay-physics claim, not a measured LSL range.
Potential Proposal Use¶
Cite as the public LCS/UAS physics paper behind EW25-8806. Use modeled 1–4 m AGL as a Task 2 measurement range, not as a selected flight altitude. Use the urban-poor-fit statement in the cantonment discussion.
Linked Findings¶
- FINDING-0003
Linked Questions¶
- Q01
- Q04