Preferred Chassis Fabrication (PCF), Inc. in Tucson, AZ produces the Scorpion 4X4 all-terrain vehicle. PCF is a licensed Motor Vehicle Manufacturer (AZ License # L00008098). The Scorpion MKIV-A consists of a fabricated tube exoskeleton chassis with replaceable body “filler” panels. This chassis design is extremely rigid and durable, which provides safety-critical protection for occupants in addition to vehicle operations survivability. Integral to the chassis design is a rear tail deck (acceptable for cargo transport), air lift/tie down points, and hitch configurations for towed loads. Scorpion’s air cushioned suspension is designed to maintain even ground pressure on all four tires, independent of axle articulation, while restraining chassis roll to a minimum. Chassis ride height is operator-adjustable for changing terrain conditions and clearance requirements. This patent-pending design maximizes traction, while maintaining ride quality and control.
The drive train of the Scorpion was designed with modern military requirements in mind. The engine is a Cummins 4BT-3.9 four cylinder diesel offering 105 horsepower at 2500 rpm, and 365 foot pounds of torque at 1300 rpm. The transmission is a GM 700-R4, four speed automatic built by Team Ramco of Yuma, AZ. The transfer case is an Atlas II by Advanced Adapters. Axles are Dana 60s by Dynatrac. Steering is done via a mechanical power gear with supplemental hydraulic power assist by Lee Power Steering. This driveline package enables a high level of vehicle performance, while maintaining reliability and ease of service. While these components are unique, all are in fact commercial off-the-shelf (COTS) items. They require no special tooling, and standard service/repair practices are used for their maintenance.
The chassis is fitted with dual isolated on-board air systems for brake actuation and chassis systems. Chassis systems that are reliant on pneumatics are brakes, suspension, shifting and differential lockers. The brake system maintains priority and can draw from either air system.
The vehicle’s electrical system is 24 volts and uses military-standard controls and lighting. Wiring is constructed using sealed connectors that substantially reduce shorts and corrosion. A chassis mounted “pure-sine” inverter supplies AC power generation. This power inverter supplies 110Vac. It has “shore power” connection capability and a built in 24Vdc storage battery charger. The Scorpion MKIV-A model was specifically designed for robotic operation. The system has no steering wheel, brake nor throttle pedals. The MKIV-A is human-operated via a joystick controller. A single function mode switch facilitates the selection of digital computer control or joystick. All chassis function controls and self-protections are processed in the vehicle Primitive Control Unit (PCU).
|DARPA Urban Challenge Vehicle Requirement||Scorpion Compliance Status|
|Built on full size stock chassis or full size chassis with documented safety record||Full compliance, as documented by Arizona Motor Vehicle Manufacturer License|
|Weigh between 2,000 and 30,000 pounds fully fueled||Fully fueled weight = 5100 lbs|
|Able to travel autonomously in forward and reverse||Full compliance|
|Able to perform U-turn on 30 foot wide street||Full compliance|
|Tires, at least 4 wheels and front and back bumpers||Full compliance|
|Capable of traveling on asphalt without damaging road||Full compliance|
|All sensors/navigation equipment fully contained within or securely attached||Full compliance|
|All computing/intelligence and sensor processing contained on board vehicle||Full compliance|
|Capable of loading a mission data file on a standard USB flash drive||Full compliance|
|Wireless emergency E-stop||Full compliance|
|Comply with radiated energy safety standards||Full compliance|