Large areas across the United States are potentially contaminated with unexploded ordnance (UXO), with some ranges encompassing tens to hundreds of thousands of acres. Technologies are needed that will allow for cost-effective wide area scanning with near 100% coverage and detection of subsurface ordnance or features indicative of subsurface ordnance.
In order to be effective for detection of small UXO, the sensing altitude for helicopter-based magnetometry wide area site investigations needs to be on the order of 1 to 3 meters, which will generally only be feasible in large, open, and relatively flat terrains. While such surveys are effective in mapping large areas relatively fast, there are costs associated with these surveys, along with risks to pilots and equipment. An unmanned aerial vehicle (UAV) magnetometer platform is a logical alternative because it reduces risk to operators, is lower in costs, and has the potential of increased detection and characterization of ordnance.
The objectives of this project were to investigate and identify the primary challenges associated with a low stand-off distance autonomous UAV magnetometer platform and to provide a recommendation for the implementation of one or more autonomous unmanned magnetometer rotorcraft platforms.
The primary challenges investigated in this project included:
- The feasibility of assembling a payload package that integrates magnetometers, accurate positioning systems, obstacle avoidance systems, power infrastructure, communications, and data storage as well as auxiliary flight controls
- The availability of commercial UAV platforms with autonomous flight capability that can accommodate this payload package
- The feasibility of integrating obstacle avoidance controls in UAV platform control
- The feasibility of collecting high quality magnetic data in the vicinity of an UAV
Researchers conducted a payload evaluation, evaluated the availability and performance of commercially available autonomous UAV systems, analyzed the requirements posed by obstacle avoidance and evaluated whether these requirements can realistically be accommodated in an autonomous UAV, and conducted a series of ground-based noise tests using a realistic UAV-magnetometer combination.
Based on the results of this project, it was concluded that the challenges associated with construction of an effective autonomous UAV magnetometer platform can be resolved and that construction of an autonomous UAV magnetometer platform is feasible. Such systems would be applicable to a number of Department of Defense sites, the modular components required to build such systems are available and sufficiently mature, and if appropriate care is taken in platform selection and component integration, the performance of such systems is comparable to manual surveys. There is a continuum of systems that could be designed ranging from systems based on rotorcraft with 10 lb payload (such as the Mongoose) to systems based on rotorcraft with 250 lbs payload (such as the Mosquito).
Assessing the feasibility of key components of an autonomous UAV helicopter-magnetometer system is an essential first step to realizing such a system. Operationally, these systems can be expected to provide improved resolution over current manned helicopter-magnetometer systems as well as near 100% coverage, the ability to map areas that currently cannot be mapped sufficiently because of rough and vegetated terrain, and cost per acre reductions, enabling potential application to smaller sites.