A state-constrained vehicle-follower approach to the station-egress problem

Vehicle following represents one approach to the longitudinal control of vehicles in an automated guideway transit (AGT) system. Requirements for the use of such control for the merging of a vehicle from an off-line station into a mainline vehicle stream are discussed. Recently, a technique has been developed that incorporates state-variable constraints into the control law of a vehicle-follower controller. A successful application of this technique to the station-egress problem has been formulated which safely merges the egressing vehicle between two vehicles initially operating at minimum headway on the mainline. It is demonstrated that for short headway operations of approximately three seconds or less, the finite length of station ramps introduces to the developed control laws an additional constraint, which must be implemented to assure safe operations. Finally, design trade-offs are shown to exist between the egress ramp lengths and the relative disturbances to mainline traffic as a result of station-egress maneuvers.