Advanced differential carrier-phase GPS techniques - in conjunction with an inertial sensor (fiber-optic gyroscope), existing wheel outputs from the anti-lock brake system (ABS), and a centimeter-accurate road database - can be used to improve safety, vehicle performance, and driver comfort. Thus far, experiments have indicated that GPS can provide centimeter-level location and velocity data in a relatively unobstructed Interstate Highway environment. In tracking a vehicle over a 3.2-km freeway loop, a combination of techniques provided accurate location and attitude data 96% of the time. On a more cluttered stretch of freeway, the method provided centimeter-location accuracy 90% of the time. These availability data are for GPS only. When GPS signals were blocked for short periods of time, a gyroscope and ABS outputs were able to increase availability by accurately tracking the path of the vehicle. With improvements in the GPS constellation and technology improvements through ongoing research and development efforts worldwide, it is anticipated that even further advances in high-accuracy location capabilities will be available for the next generation of driver assistance systems. Adaptive cruise control, drivetrain management, active steering of headlights, heading control, lane departure, collision-warning and collision-avoidance systems, and fully automated vehicles can benefit from precise location data. (A*)
Samenvatting