The Surrogate Teleoperated Vehicle (STV), a scaled-down follow-on version of the TOV concept, was developed under contract to SSC San Diego by Robotic Systems Technology (RST), Inc., Westminster, MD, for the UGV/JPO in Huntsville, AL. The STV was intended to serve as a prototype system supporting the near-term development and evaluation of operational concepts for future unmanned ground vehicles, hence the terminology "Surrogate." A total of 14 vehicles was delivered to allow large numbers of military personnel to gain valuable hands-on robotics experience that could appropriately influence subsequent acquisition strategies.
From a technical perspective, the STV can be decomposed into four major inter-related subsystems: 1) the Remote Platform, 2) the Mobility/RSTA Module, 3) the Operator Control Unit, and 4) the Communication System.
The Remote Platform is built around a modified Polaris Industries Big Boss six-wheel-drive all-terrain vehicle measuring 117.5 inches long and 50.5 inches wide (Myers, 1992), capable of traversing through water upto 2 feet deep. The principle power source is a water-cooled three-cylinder 25-horsepower diesel engine built by Fuji Heavy Industries, capable of propelling the vehicle at speeds up to 35 miles per hour. The output shaft of the diesel drives a modified Polaris variable belt transmission that in turn is coupled to a gearbox providing neutral, reverse, low-forward, and high-forward speed ranges (RST, 1993). An auxiliary 3-horsepower electric golf-cart motor is also coupled to the gearbox input shaft (via an electric clutch) to provide for extremely quiet movement during surveillance operations at limited speeds up to 4 miles per hour. The gearbox output shaft powers the tandem rear axles through an exposed chain-drive arrangement. Two 12-volt sealed lead-acid batteries supply all required DC power, recharged by a 24-volt 60-amp engine-driven alternator.
In similar fashion to its TOV predecessor, the STV Mobility/RSTA Module consists of a number of reconnaissance, surveillance, and target acquisition sensors mounted on a pan-and-tilt mechanism situated atop an extending scissors-lift mast. In a stowed configuration, the mast is only 24 inches high, but can raise the sensor pod when desired to a full height of 15 feet above ground level. Adjustable pneumatic springs in the rear of the vehicle allow for stiffening of the suspension when the surveillance mast is elevated, thus reducing sway and jitter during RSTA operations (Metz, et al., 1992). The mobility and RSTA sensors include:
- A stereo pair of 460-line day driving cameras.
- An image-intensified camera-pair for nighttime driving.
- A day targeting camera equipped with a 14-to-1 zoom lens.
- An image-intensified night targeting camera with a 10-to-1 zoom lens.
- An IRIS-T FLIR (forward-looking infrared).
- Either an LTM-86 laser ranger/designator, or an ESL-100 eye-safe laser ranger.
The STV Communications System allows the vehicle to be controlled from the man-portable Operator Control Unit using either a deployed fiber-optic tether or a back-up RF link (RST, 1993). The 10-kilometer inside-wound fiber-optic spool is packaged in a 3.5 cubic foot cargo-box area behind the engine compartment, with a hinged lid for easy access (Myers, 1992). A low-tension payout scheme feeds the 2.5-millimeter cable out the back as the vehicle moves forward. The RF back-up communications system consists of (RST, 1993):
- A 9600-baud full-duplex (dual-frequency) Repco SLQ-96 Radio Modem for command and status data.
- A Repco Utility Data System (UDS) FM transmitter for audio to the vehicle.
- A Dell-Star Technologies 900-Series video transmitter for video and audio from the vehicle to the Operator Control Unit.
The maximum effective operating range under level-terrain conditions in the RF mode is approximately 2 kilometers.
The Operator Control Unit uses a motorcycle-type steering device for vehicle mobility control, with a two-degree-of-freedom joystick for camera pan-and-tilt.