Design and experimental implementation of longitudinal control for a platoon of automated vehicles

This paper presents the design and experimental implementation of a longitu dinal control system for the operation of automated vehicles in platoons. T he control system on each vehicle is designed to have a hierarchical struct ure and consists of an upper level controller and a lower level controller. The upper controller determines the desired acceleration for each vehicle in the platoon so as to maintain safe string-stable operation even at very small intervehicle spacing. The lower controller utilizes vehicle-specific parameters and determines the throttle and/or brake commands required to tr ack the desired acceleration. A special challenge handled in the design of the lower level controller is low-speed operation that involves gear change s and torque converter dynamics. The paper also presents the design of long itudinal intra-platoon maneuvers that are required in order to allow any ca r in the platoon to make an exit. The paper presents extensive experimental results from the public NAHSC demonstration of automated highways conducte d in August 1997 at San Diego, California. The demonstration included nrl e ight-car platoon operating continuously over several weeks with passenger r ides given to over a thousand visitors. The maneuvers demonstrated included starting the automated vehicles from complete rest, accelerating to cruisi ng speed allowing any vehicle to exit from the platoon, allowing new vehicl es to join the platoon and bringing the platoon to a complete stop at the e nd of the highway.