Navigation of an autonomous ground vehicle using the subsumption architecture

The subsumption architecture is used to provide an autonomous vehicle with the means to stay within the boundaries of a course while avoiding obstacles. A three-layered network has been devised incorporating computer vision, ultrasonic ranging, and tactile sensing. The computer vision system operates at the lowest level of the network to generate a preliminary vehicle heading based upon detected course boundaries. The network's next level performs long-range obstacle detection using an array of ultrasonic sensors. The range map created by these sensors is used to augment the preliminary heading. At the highest level, tactile sensors are used for short-range obstacle detection and serve as an emergency response to obstacle collisions. The computer vision subsystem is implemented on a personal computer, while both ranging systems reside on a microcontroller. Sensor fusion within a subsumption framework is also executed on the microcontroller. The resulting outputs of the subsumption network are actuator commands to control steering and propulsion motors. The major contribution of this paper is as a case study of the application of the subsumption architecture to the design of an autonomous ground vehicle.