Operational Concepts and Implementation Techniques for Vehicle-Follower Control of AGT Systems

摘要

This report presents a new baseline approach for the vehicle-follower for the longitudinal control of Automated Guideway Transit (AGT) vehicles. It is shown that for the short headways (0.5 to 3.0 s) contemplated for such systems, a kinematic constraint on the spacing between vehicles exists during speed transit maneuvers. This constraint is a nonlinear function of the service jerk and acceleration limits imposed on vehicle operation and also on the instantaneous values of the state variables of neighboring vehicles. The constraint is explicitly included in an analytical development of the control law, which is then shown to control satisfactorily vehicles during overtaking maneuvers and merging maneuvers up to full line capacity, and to regulate perturbations about nominal operating conditions. Modification of the kinematic constraint is then shown to generalize the approach to the problem of vehicle egress from an off-line station into main line traffic flow, including gap generation. Minimum required station egresslane lengths are then established as a function of headway. The station egress control is shown to be safe and effective even in the event of off-nominal behavior of vehicles in the main line traffic flow. Finally, the implementation requirements for the control are shown to be best satisfied by a 'smart' vehicle control configuration, with state variables for vehicle spacing, velocity, and acceleration transmitted through wayside equipment at intervals of approximately one-fifth operational headway. Other headway-dependent factors determined in the implementation analysis are the permissible time delay for data transmission, the required on-board computation rate, and required levels of digital quantization. Results indicate that the control is compatible with existing microprocessor technology.