Asset Inspections by Multispectral Imagery

Risk Reduction Category

Asset Monitoring

Technology Description

Today, utilities commonly use imagery from unmanned aerial systems (UAS) to improve their vantage point when inspecting overhead assets. Depending on terrain and access, an aerial inspection can be done faster versus visual inspections on foot, even with current line-of-sight restrictions for drone operation. Additionally, aerial imagery provides a beneficial visual perspective for inspections of overhead assets.

The sheer physical size of the transmission and distribution infrastructure makes inspecting those assets challenging. Utilities usually use a combination of ground-based patrols and manned aircraft flights for routine and emergency response inspections. These traditional approaches are costly, time consuming, and require human involvement.

Multispectral cameras can extend the information gathered during aerial inspections, capturing information that is otherwise indetectable with standard visual (RGB) cameras. Most multi-spectral cameras capture RGB imagery along with imagery in the infrared and ultraviolet wavelengths. The extended bands can be captured at the same frame rates and resolutions as their visual counterparts, providing layers of imagery that can be analyzed by humans or AI.

  • Visual (RGB) – captures bands detectable with the human eye (red, blue, and green)
  • Infrared (IR)– detects heat signatures
  • Ultraviolet (UV)– can reveal arcing, partial discharge, and flame

The addition of the IR band to traditional visual inspections increases the use cases to include: [1]

  • Detecting issues with underground electrical distribution [2]
  • Detecting water leakage from underground piping systems [4]
  • Detecting methane emissions from natural gas infrastructure [3]
  • Detecting evidence of corrosion from re-bar and cracking due ASR in containment structures
  • Using TIR/NIR sensors to conduct nesting bird surveys and bat emergence counts

The addition of the UV band to traditional visual inspections increases the use cases to include: [1]

  • Helping determine locations of power line corona discharge [3]
  • Improving personnel safety by eliminating the need to access elevated locations.
  • Reducing operating costs by identifying faults more quickly, which reduces time to inspect equipment.

Hyperspectral cameras operate in the same energy spectrum as multispectral cameras, but with many narrower bands. Hyperspectral cameras are not typically used today for aerial inspections because of cost and complexity, but the extra capability expands use cases, including: [1]

  • Identifying deteriorating wood pole top conditions due to moisture ingress
  • Detecting biological growth around plant coolant intakes and discharge areas
  • Detecting evidence of corrosion from re-bar and cracking due to alkali-silica reaction (ASR) in containment structures

What is envisioned is a periodically self-deploying UAS, located in a sheltered charging station, that would fly a programmed (or self-guided) route around utility assets. Imagery collected by the UAS could be uploaded to a cloud service or processed locally. Machine learning would analyze the imagery, detect anomalies, and send alerts upon detection of these anomalies.

Technical Readiness (Commercial Availability)

Aerial inspections of utility asset via multispectral camera technology is a complex combination of state-of- the-art technologies:

  • Automated UAS flight - As of 2023, most UAS deployed by utilities are manually operated, however, as technology improves automation is increasingly possible. A challenge with automated aerial asset inspections has to do with the ability to capture useful imagery [1]. Although seemingly straightforward, image capture is highly dependent on precise positioning of the UAS for the best view of an asset. Also, lighting, truncation, and obscuring of the asset of interest can be factors. This challenge is being addressed by improvements in navigation technology. For example UAS are now capable of identifying poles in flight and moving in a prescribed path around each pole in order to better capture visual attributes of the asset. Another of the immediate challenges today involves FAA regulations against flying a drone beyond line of sight of an operator. Gradually, the FAA is loosening some of these restrictions and waivers are being granted within specified conditions.
  • Camera technology - As of 2023, multispectral cameras are suitable for drone mounting, having portability and capability to capture images from a moving camera at focal distances of a few meters. With today’s technology, imagery can be stored on the machine itself or transmitted wirelessly during capture.
  • Data processing and anomaly detection – As of 2023, with sufficient training data, machine learning has been demonstrated to be effective at detecting anomalies in imagery.
  • Use case: Asset Inspections by Multispectral Imagery – Combining technologies into an asset inspection use case is the next step. More needs to be known about the efficacy of the data gathered, the ability to retrieve actionable information, number of false positives and missed positives, and costs of the effort.

The following list of manufacturers is the product of an Internet search using a general description of the technology as the search term. Sometimes more than one variation on the search term is used. The objective is to identify the most demonstration-ready products available in the category. Toward assessing demonstration readiness, the manufacturer websites typically provide useful information such as writeups of successful use cases or field demonstrations, number of deployments, or other indicators. Where lack of information exists online, further inquiry is made by phone. Generally, one to three frontrunners emerge as being most ready for a field demonstration. Preference is given to manufacturers who sell to the United States, or, if emerging technology, those who have participated in US-based field demonstrations.

Implementations/Deployments

While the technologies involved in carrying out the use case are commonly used today, combining them effectively into an asset inspection use case is the next step. More needs to be known about the efficacy of the data gathered, the ability to retrieve actionable information, number of false positives and missed positives, and costs of the effort.

Innovations as of Mid 2023

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Potential Enrichment Work Opportunity

References

[1] UNMANNED AIRCRAFT SYSTEMS (UAS): Advanced Payloads. EPRI, Palo Alto, CA: 2018. 3002015063.

[2] Weisenfeld, Neil et al. “Infrared Scanning Reveals Defects.” Tdworld.com. https://www.tdworld.com/underground- tampd/infrared-scanning-reveals-defects. (Accessed September 2018).

[3] Rebecca DelPapa Moreira Scafutto et al. “Evaluation of thermal infrared hyperspectral imagery for the detection of onshore methane plumes: Significance for hydrocarbon exploration and monitoring.” International Journal of Applied Earth Observation and Geoinformation 64 (2018) 311-325. https://www.sciencedirect.com/science/article/pii/S0303243417301411. (Accessed September 2018).

[4] Santovasi, Steve and Evans, Laron. “UAS Technology Offers Soaring Potential.” Burnsmcd.com.https://www.burnsmcd.com/insightsnews/tech/uas-technology-offers-soaring-potential. (Accessed September 2018).