Synchronous Control of Vehicle Following Behavior and Distance Under the Safe and Efficient Steady-Following State: Two Case Studies of High-Speed Train Following Control

Vehicular safe and efficient steady-following state should be maintained, or recovered, or reestablished by the following vehicle adapting its own behavior to the leading vehicle's dynamic behavior. For this purpose, the synchronous control of vehicle following behavior and distance needs to be solved. The following vehicle under a new velocity-difference control, which is based on the abstraction fitting function of the absolute safe following distance changing with the following vehicle's velocity, is mathematically proved to have the ability to maintain, recover or reestablish vehicular safe and efficient steady-following state. The theoretical analysis and simulation results of high-speed train following control show that when a safe and efficient steady-following state is broken by the behavioral change of the leading vehicle, the new velocity-difference control method would have the following vehicle adjust its own behavior in safety, efficiency, and smoothness (comfort). Vehicle following system would enter the previous/new safe and efficient steady-following state again if the leading vehicle begins to travel at a previously/newly constant velocity for enough time. The new velocity-difference control would also have the following vehicle keep an even speed to maintain the currently safe and efficient steady-following state if the leading vehicle does not change its behavior. This finding can have vehicle following control to be studied: under the safe and efficient steady-following state, and from other states to the safe and efficient steady-following state. It may be helpful for further study of vehicle following control.