Normal and emergency control of a string of vehicles by fixed reference sampled-data control

This paper concerns controlling a string of vehicles on an automated highway using a sampled-data fixed reference control system suitable for a "moving cell" control scheme [1]. The reference consists of equally spaced information stations (posts) along the roadside. See Figure 1. As a car reaches a post, it receives data concerning its time of arrival error (convertible into position error) plus the value of the command velocity. Each car contains a means for measuring its own velocity. Thus an on-board controller independently controls each car using position error and velocity error. The shock wave effects of moving reference (car-following) systems [1] and the inter-car communication requirements of state feedback approaches to this problem [2] are avoided. Control is simple since each car controls itself and each post simultaneously sends the same information as all other posts. No inter-vehicle communication is required. The posts can also be used to monitor system behavior and detect emergencies, although this monitoring function is not discussed here.