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The complete ROGUE system consists of robotic tug, EM-61/magnetometer trailer with buck-out coil, remote control site, navigation computer and secondary data acquisition system (DAS). The system is complete with a real-time kinematic GPS that is usually accurate to within ± 2 centimeters dependant on satellite configuration, field of view and the accuracy of initial base station coordinates.
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Rogue Robot in the field
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The ROGUE may be teleoperated with a joystick or semi-autonomously with preprogrammed waypoints. During semi-autonomous operations the ROGUE automatically goes to each waypoint and once the waypoint is acquired it navigates to the next waypoint until it acquires the last waypoint. Video, navigation and geophysical data are transmitted back to the remote control site with internal radio modems mounted into the ROGUE chassis. The geophysical, navigation, and positional data are multiplexed in the ROGUE CPU, unscrambled at the control site and output to the serial ports on the navigation computer and displayed on the control console. Data is stored in the navigation computer and with the data acquisition system. The external data is output via the serial port from the navigation computer and input to the DAS via a multiport serial interface.
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The control console on the navigation computer shows the position of the GPS base station and the robot location, streaming geophysical and heading data, trailer hitch angle and programmed waypoints. The trailer hitch angle data is used to determine the precise position of the geophysical sensors and determine if the trailer is jack knifed. If the CPU on the ROGUE determines the trailer is jack knifed the robot will automatically pull forward until the trailer is properly aligned for normal operation and continue to the next waypoint.
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The DAS consists of a hydrographic software program (Trimble Navigation's HYDROPro®) loaded onto a Windows 98 platform. This program takes the serial data in for each sensor and GPS data streams, simultaneously stores and displays the data with offset positions tagged to each sensor. Real-time graphed profiles of the geophysical data, background digital line maps, robot position and sensor offsets, preprogrammed lines (guidance objects or GO), and offline indicator bar are displayed on the monitor. In addition, the DAS will use a course-made-good (program assumes a constant velocity to estimate position until GPS is reacquired) when loss or poor differential GPS is encountered during a data collection event. The ROGUE can be easily navigated down lines with offline bar or with the video display with the joystick.
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Marine System Design
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The fully equipped ROHICA has a zero signature at approximately 3 feet forward of the vessel. For positioning a real-time differential GPS system was used in conjunction the GEM Systems Overhauser Effect model GSM-19™ magnetometer. Qualitative measurements were taken around the ROHICA for placement of the magnetometers, GPS and radio modems.
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The magnetometer array was mounted on the ROHICA, a small barge (8 feet by 6 feet wide), and towed in and out to sea. The magnetometer sensors were mounted in the aft 6.56 (2 meters) apart on the port and starboard of the ROHICA (see Figure 2). The GPS antenna was mounted between the two magnetometer sensors and GPS receiver and radio modems were placed sufficiently far away as not to induce any EMI. Radio modems were attached to magnetometer and GPS for real-time data transfer to the remote command post. The ROHICA was remotely towed to and from shore with a winch and pulley system that was mounted on a second barge (BOHICA). Explosive ordnance disposal (EOD) personnel cleared the shoreline prior to allowing personnel or vehicles on to the beach. A snatch block pulley assembly was attached to the shore side with a rope affixed between to vehicles. This snatch block pulley was positioned on the active line either with the ROHICA GPS or a tape measure depending on whether the ROHICA was at shore site or at sea side.
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Data were transferred via radio modem data links from the ROHICA and positional data from the BOHICA to the remote command post in real-time. The command post was equipped with the same DAS used with the ROGUE. The DAS is the receptacle for all data (GPS and magnetometer) and the position of each sensor is stored into a database. The data acquisition computer was complete with a multi-port acquisition card that allowed all data to be streamed into the navigation/acquisition program simultaneously.
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The transect lines were preprogrammed into the navigation/acquisition program and the vessels were navigated from the command post by the remote navigator. Once the remote navigator directed the vessels to the appropriate line then the vessel was remotely towed from the BOHICA to or from the shore when data were then collected and transmitted to the command post. At the completion of the current line then the shore side pulley was moved to the next line and the BOHICA was navigated to the next line by the remote navigator.
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Results
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Both geophysical platforms met the objectives of supplying an unmanned solution to UXO mapping in extremely hazardous environments. Both systems were proven to have a very low magnetic and electromagnetic signature and robust in there respective field scenarios.
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ROGUE Robotic Platform
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The ROGUE can detect ferrous and non-ferrous ordnance as small as 40 mm projectiles in semi rugged terrain. The ROGUE is a comprehensive and relatively cost effective solution to unmanned semi-autonomous detection of UXO. The system has been operated at line-of-site distances of one mile with all systems working properly. Unfortunately, at the time this paper was drafted the ROGUE has not been sent on an actual mission. Field tests have been performed where the system performed flawlessly with all instrumentation operational. Some problems associated with overhead canopy (loss of GPS position) and mobility (steep terrain, thick under brush, and slopped wet grass) have been encountered. The system is capable of running up to 4 hours of continuous fieldwork before the batteries for the robot, magnetometer and EM-61 need to be replaced.
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Funding for the project described in this article has been provided in full or in part by the U.S. Environmental Protection Agency. This abstract has not been reviewed by the Agency, therefore, no official endorsement should be inferred.
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