Preview based control of a tractor trailer using DGPS for preventing road departure accidents

In order to reduce the number of road departure accidents caused by fatigue and driver inattention, we are investigating intervention strategies during critical situations, part of a human centered approach to lateral vehicle control. Alarms and warning devices are for the most part ineffective since their effects on a fatigued driver are only short term. We have designed and integrated a system which monitors the vehicle/driver's behavior noninvasively and takes over control if he react inappropriately. The vehicle is then steered to the next appropriate shoulder and stopped. We are using a preview based controller implemented on a Navistar 9400 series tractor-trailer comprised of a "pursuit" algorithm which steers the vehicle towards goal points on the road, stored as a digital map. This map which represents the roadway's geometry is generated by previously recording the road's corresponding DGPS coordinates. A Novatel RT-20 second generation DGPS system is the primary sensor modality for providing position and orientation feedback with respect to a global coordinate system with a yaw rate gyro providing additional feedback. Heading error and yaw rate are used to control the truck's steering control subsystem. This lateral control system, the first system using DGPS for truck lane keeping on a standard road, has been successfully demonstrated through field experiments at the Minnesota Department of Transportation's research facility. We focus on the computer control of steering.