The initial tow vehicle is a modified Segway RMP 400 (http://rmp.segway.com/). The Segway’s built-in charging system was removed to minimize its effect on the towed sensors. The chassis contains a rugged onboard computer (Advantech ARK3300 Series), a Novatel SPAN® GPS/INS system (global positioning system/inertial navigation system) for position information, communications equipment including a 900MHz Ethernet radio modem (Freewave HTplus) and two analog cameras connected through an Axis networked video server. An optical encoder is used to measure the angle between the trailer and vehicle. Trailer position can be determined from the combination of GPS/INS data and encoder measurements or alternatively from a second GPS receiver.
A second, more rugged version of the system was constructed. A custom fiberglass chassis was built to provide a water resistant enclosure for the electronics and further reduce the system’s EM signature. An adjustable height arm was mounted to a roller bearing supported shaft on top of the chassis to provide an attachment point for a trailer. The adjustable height allows trailers with different height wheels to be kept level.