Unified approach to vehicle follower longitudinal control system design

Abstract

The longitudinal control system for a vehicle follower automated transit vehicle has the dual requirements of controlling the vehicle speed and also the spacing between vehicles. Previous attempts at designing these loops individually has resulted in a control system where the two loops are in conflict. Proposed techniques for resolving this problem have required that the loops be switched in and out depending on the control mode. A simplified control system structure with both spacing and velocity loops operating simultaneously is proposed as a solution to the vehicle follower control problem. The operating gains for these loops are based on using a subset of the gains derived by linear optimal control theory corresponding to the actual loops present. The final controller design uses gain scheduling on the spacing loop integral gain term. This system is shown to operate effectively in the presence of both large and small spacing errors.