Communications of the ACM
Backpack Mapping System Captures Intelligence in Tough-to-Get-to Places
An APL engineer uses EMAPS aboard a ship (above) to generate a map (below). The red line marks his path, and the colors show radiation levels on board.
Credit: Johns Hopkins University Applied Physics Laboratory
Engineers at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., have developed a portable device that can be used to automatically create annotated maps in tight spaces where GPS is not readily available — such as in underground areas and on ships.
Produced for the Defense Threat Reduction Agency, the Enhanced Mapping and Positioning System (EMAPS) is carried in a backpack and captures a floor-plan style map of the area traversed, as well as 360-degree photos and sensor readings of environmental data collected in the area using a variety of sensors.
The system improves upon algorithms originally designed for robots which have trouble maneuvering in some environments and it has a built-in allowance for the dynamic motion generated by walking and other normal human movement. The APL team also programmed EMAPS to map challenging environments that stumped older algorithms, such as open areas and long, smooth hallways.
Using the APL-developed EMAPS, environmental information is captured while operators carry its approximately six-inch, four-pound cube in a backpack. Light, Detection and Ranging (LIDAR) sensors, also developed at APL, blanket an area with narrow beams of light, coming from literally every angle. The "hits" are quickly processed into extremely detailed views of the area traversed. Designed mainly to detect and map environmental threats on ships and other tough-to-get-to locations, EMAPS' novel algorithms allow maps to be generated from the compact backpack system and associate critical environmental data, such as radiation or radio frequency signal levels, with map locations.
The basic EMAPS unit uses a 270-degree laser scanner to measure distances to walls and features in the environment. "EMAPS virtually takes pictures with every step," says Jason Stipes, a researcher in APL's Force Projection Department. "Using this technology we can map almost every nook and cranny of targeted locations, capture that intelligence, and store it. Its sensors can also detect threats such as radiation or chemicals and include them in our map."
A second laser scanner allows 3-D data collection and an inertial sensor measures the roll, pitch, and yaw of the system to detect the user's steps. In addition, the system can accommodate a removable camera for capturing omnidirectional images; a GPS receiver to allow for geo-registration of any data collected; and a solid-state hard drive for real-time data processing and storage.
"EMAPS software addresses a number of challenges using specially-developed algorithms," says Stipes. "Working with DTRA, APL engineers created it to efficiently map data without boundaries while using a fixed amount of computer memory."
To date, the EMAPS unit has collected more than 100 hours of mapping data from a wide array of GPS-denied environments including six different ships, underground storage facilities, Army training areas, and buildings. Maps have been completed with paths several miles long in environments ranging from simple office buildings on the APL campus, to complex ship engine rooms, to the Smithsonian Natural History Museum. Ongoing development efforts aim to further improve algorithm performance and fidelity while adding even more useful data products.
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