Feature ArticlesUsing Micro-ROVs for the Inspection of Underwater Mines
By Mark Feulner
Assistant in Research
Underwater Crime Scene
College of Criminology and Criminal
Florida State University
Panama City, Florida
Protecting harbors and commercial waterways from submerged threats is a critical aspect of maritime security. Developing the tools and techniques for identifying and mitigating such threats is only part of the solution. Due to the location and nature of most ports, coordinating the efforts of the various agencies that would be involved in security activities is a significant challenge. The 2008 Maritime Homeland Security Experiment (MHSE) in Tampa, Florida, sought to address these issues.
The MHSE was an experiment rather than an exercise in that the focus was on evaluating the tools that may be employed in port security activities and testing the incident command system (ICS) that would be used to coordinate a multiagency effort. The scenario involved the planting of a submerged improvised explosive device (IED) by unknown agents in the channel leading into the harbors of Tampa Bay.
The agencies involved in this experiment included the Naval Surface Warfare Center (NSWC) in Panama City, Florida; the U.S. Navy Explosive Ordnance Disposal (EOD); the National Forensic Science Training Center (NFSTC); an underwater crime scene investigation (UCSI) team from Florida State University, Panama City; the local U.S. Coast Guard station; and others. In the scenario, the Coast Guard played the role of commanding agency. NSWC provided the tools and personnel for conducting harbor inspections, an aspect of the operation that relied heavily on autonomous underwater vehicles (AUVs) for the detection and identification of submerged threats, and EOD personnel supervised the neutralization of the threat. In addition to providing site investigative functions, the UCSI team was also tasked with staging the target and setting the debris field.
The Mission Plan
The UCSI team was to perform three primary functions. The first function was to perform a close inspection of the device to evaluate the threat and initiate the investigation. The team was also to identify the extent of the scene and stabilize it, seeking to preserve or document as much evidence as possible through the threat mitigation process. The overall task was to conduct an investigation of the incident site reaching from initial identification of the threat through the mitigation phase and into follow-up activities. The behind-the-scenes focus of the UCSI team for this operation was not so much the development of diving capabilities, but rather the use of technology to alleviate the burden on the divers and increase safety.
A large portion of the activities involved the use of remote sensing technologies. This was due to the hazard posed by the device in the simulation. In real-world situations, divers from public safety dive teams would not enter the water when unexploded ordnance is involved. Therefore, until the EOD mitigation of the threat was completed, forensic operations involved using sonar and remotely operated vehicles (ROVs) to complete the initial tasks of site inspection and threat analysis.
Another facet of the evaluation phase was the identification and preservation of any evidence found to be associated with the IED. This provided not only the most significant challenge, but also perhaps one of the most critical. The identification of submerged threats is normally done acoustically, and the imaging provided is limited. In many cases, the exact nature of a threat is unknown or merely suspected until an EOD diver makes contact with it. At this point, the process is in the mitigation phase, during which much of the evidence would be destroyed and hamper subsequent investigations. The UCSI team would provide a close inspection of the device prior to its mitigation to both gather evidence and provide EOD divers with more information about the threat before entering the water.
The scene stabilization was rather straightforward, and much of this activity was shared among the agencies involved. The AUVs deployed by the Navy did most of the data gathering. A significant feature of this phase was the sharing of information among agencies to facilitate the planning and coordination of subsequent activities. The evaluation of this transfer of information up the chain of command to the Incident Command Post (ICP) and then back down to various players was one of the key objectives of the experiment.
Post-mitigation activities involved the deployment of forensic divers to conduct final documentation of the scene and recover any remaining evidence. This was done in coordination with other agencies, synthesizing the information generated by the AUVs, ROVs, sonar equipment and EOD divers to provide the best possible overview of the site and thereby facilitate the final investigation. While these activities wrapped up the investigative process, additional investigative activities naturally coincided with other exercise components.
Several key functions were identified that needed to be conducted remotely. First, it was determined that acoustically mapping the site would provide a great deal of information without deploying divers and assist in the navigation of the ROV and the later deployment of divers. A Sound Metrics (Lake Forest Park, Washington) DIDSON multibeam sonar was used for this purpose. The task of macroimaging evidential features provided a bit of a challenge. The last function was to physically gather samples using the ROV, which turned out to be a rather simple operation.
To obtain a macroimage using the technology on hand, the team initially sought to build an optical magnifier using a submersible drop camera. The ROV used was a VideoRay LLC (Phoenixville, Pennsylvania) Pro III, and the magnifying lenses needed to be deployed from this platform. Upon fabricating and testing such a magnifier, it became immediately obvious that this was not the best method. The primary concerns were that the system was cumbersome, would require an independent monitor and recorder and would necessitate an additional cable that would need to be whipped to the ROV tether. Troublesome seals and the requirement to convert and transfer collected images into the command network led to the conclusion that the likelihood of extensive in-field troubleshooting was too great.
During this developmental testing, it was discovered that a lens placed in front of the ROV camera provided a fairly good image and that a properly spaced pair would provide the requisite image quality. While affixing lenses in this fashion would achieve the desired macroimaging, it inhibited the operator's ability to visually pilot the ROV.
To solve this problem, a system of levers to raise and lower the lenses was constructed using brass. The levers would be actuated by the manipulator arm of the ROV, raising and lowering as the claw opened and closed. This lever system was mounted to the skids of the ROV. Their placement was streamlined as much as possible to reduce drag and fouling issues.
The team needed to use as little brass as possible because it added a significant amount of weight to the ROV. Buoyancy in the form of a flat strip of foam attached to the starboard skid was added to correct a severe list while maintaining a low-drag profile. The weight of the magnifier made precision control easier by slowing down the ROV and enhancing stability. The final design consisted of a modular underwater magnifier from Night Sea (Bedford, Massachusetts) that could be adjusted along the lever arm for optimal magnification.
Conducting the Operation
The operation was delayed by several days due to weather caused by Hurricane Gustav. The exercise was conducted out of the Port of St. Petersburg, Florida, with the captain of the port acting as incident commander. The ICP was located at the Coast Guard station.
There were three engagement areas in which various aspects of the operation were conducted on the water. The primary area for the scenario was Engagement Area 2, where the mock IED and debris field were planted. The area was surveyed several times using AUVs, both before and after the IED and debris field were planted. This was to provide a baseline for comparison and simulate the discovery of something that did not belong there. After the Navy AUVs successfully located the device, the position of the target was relayed to the UCSI team through the ICP.
The UCSI team deployed to the site to investigate the simulated anomaly that had been located by the Navy's AUV survey. A polemount was used to deploy the DIDSON, which was used to locate the target.
This provided an improved image of the anomaly and helped navigate the ROV to the device.
As had been anticipated, there was a significant amount of biological material suspended in the water. It had been hoped that the magnifier would help offset this issue. A variety of serial numbers and other identifying marks were present on the device, and the surface of the device was marked with fingerprints in a material that was not water soluble. The objective of this first close inspection was to detect these features, document them and relay the data to the ICP. This information would be distributed to the EOD and the NFSTC to support their respective roles in threat mitigation and forensic analysis.
The magnifier worked extraordinarily well in obtaining macroimages. Screen captures of the video pulled from the ROV were relayed to the ICP and NFSTC's mobile forensics lab onshore. Sufficient details were identifiable in several of the fingerprint images for the purposes of comparison through an augmented fingerprint identification service.
For the second objective, a different ROV was used. A VideoRay Scout was deployed to obtain a swab sample of a substance detected on the device during the first inspection. To obtain the sample, a sampler from a forensics field test kit was mounted on the end of a small fiberglass rod. It was positioned to be just within the field of view of the Scout, so the operator could see where the swab contacted the substance.
The substance on the IED was Vaseline mixed with TNT residue, and the swab was part of a field test kit for explosive materials. Though piloting the Scout into position for scraping off a sample was difficult, the ROV operator was able to gather enough residue for testing. In future iterations of this activity, a more rigid mount for the swab would facilitate the sampling process.
In the end, the close inspection provided by the ROV was successful. It allowed the UCSI team to accomplish its tasks of information gathering, target evaluation and initial evidence collection without exposing divers to any unnecessary risks. Additionally, the successful use of a weighted tether provided the ability to operate the ROV great distances from the operations vessel without the problem of tether 'sailing,' further increasing the margin of safety. Future experiments will seek to expand on the capabilities that were demonstrated in Tampa. The foremost of these is the control of the ROV through Internet protocols, allowing operators in the ICP to take control of the ROV on site to complete various tasks.
Mark Feulner has been an underwater crime scene investigation research faculty member at Florida State University, Panama City, since 2003. He holds master's degrees in underwater archaeology from Texas A&M University and criminology from Florida State University.
Richard Martincich is a graduate assistant in criminology at Florida State University, Panama City. He holds a bachelor's degree in criminology from Florida State University, Panama City, with a minor in underwater crime scene investigation.