An investigation into a string-stable vehicle following control strategy for stop-and-go cruise control

A string-stable vehicle following control strategy for stop-and-go (SG) cruise control is presented in this paper. Stop-and-go cruise control systems should be designed such that a string of the controlled vehicle is string stable in addition to every vehicle in a string of SG cruise control vehicles having to track any bounded acceleration and velocity profile of its preceding vehicle with a bounded spacing and velocity error. An optimal vehicle following control law based on the information of the following distance (clearance) and its velocity relative to the vehicle ahead (relative velocity) has been used, and string stability analysis has been based on the control law and constant time gap spacing policy. The minimum time gap for string stability has been obtained on the basis of the analysis, and the results have been verified via computer simulations. Simulation studies have been carried out using a multivehicle simulation package validated using vehicle test data. It has been shown that the minimum time gap for string stability from the string stability analysis is a good estimate to give a quantitative value for a string-stable SG cruise controller.