Technical Social and Economic Issues

Technical Social and Economic Issues

Introduction

While driverless cars gliding accident-free down automated roads remain years--or more likely decades--away, test tracks and roads now in use or being built are making use of technologies and techniques that might well find their way into tomorrow's intelligent roads and vehicles.

One such test facility is the 1.8 mile oval WesTrack at the Nevada Automotive Test Center near Carson City, NV. A visitor to that track would see four Navistar tractors pulling triple trailer combinations around the track virtually around the clock. That is part of a project to test 26 different experimental asphalt pavement formulations as part of the Federal Highway Administration "Accelerated Field Test of Performance-Related Specifications for Hot-Mix Asphalt Construction" project. Using accelerated testing, 10 years and 1.7 million total vehicle miles of pavement testing can be accomplished in only two years. The test speed is 40 mph.

What's different here is that to eliminate the monotony of up to 22 hours-per-day, 7 days-per-week driving, the trucks are driverless. The autonomous tractors are equipped with electronically controlled Detroit Diesel turbocharged engines and Twin Disc automatic transmissions. Braking is done with Midland-Grau Anti-Lock Brake System (ABS) on the tractors and all trailers, plus an electronic brake valve for brake control.

Redundant guide-by-wire systems buried under the asphalt are used to laterally and longitudinally control the trucks. For added safety, all systems are connected to uninterruptible power supplies. Each tractor is equipped with guidance antennas mounted to the front bumper. Those are used to acquire the guide tones emitted by either primary or alternate wire paths, which are powered by audio amplifiers. The antennas, reading either the primary or alternate wire paths, provide a continuous feedback signal to the steering controller. Steering is accomplished by a robust stepper motor connected directly to a steering gearbox. Steering commands are based on the error signal generated from displacements from the center of the wire. The throttle, engine and transmission are controlled by advanced electronics on the engine and automatic-transmission electronic control unit.

The trucks are controlled and monitored from a control room located beside the test track. Computers within the control room start and stop the vehicles, as well as regulate spacing and speed. Radio-frequency modems on each truck are used for communications for traffic and longitudinal control. Different frequencies are used to distinguish between the vehicles that are on the track at the same time.

As a fail-safe measure, the Differential Global Positioning System (DGPS) independently monitors the truck position and provides an input to the traffic control computer. Each vehicle has two computers shock mounted in the truck's sleeper, one for vehicle control and one for monitoring more than 160 parameters on the truck's "health" that would be normally evaluated by a driver. The control room operator has one computer for each truck--with a display showing status of the truck in an easy-to-read format. There are diagnostic programs to aid in monitoring and correcting critical control ...