Research on Smooth Tracking and Control of Stair-like Target Speed with Compatible On-Board System in Urban Rail Transit

Abstract

[Objective] In view of the special phenomenon that the target speed message period is longer than the on-board control period and the message interval is not fixed in urban rail transit compatible on-board system, a dual-period speed tracking algorithm is proposed to realize smooth tracking of stair-like target speed. [Method] According to the characteristics of target speed sequence, two train control states i.e. cruise state and estimation state are introduced to identify the deceleration process before the train enters station. The target speed messages received in both the message period and the on-board control period are processed respectively. When the target speed message is received in the message period, the estimated value of the reference speed and the reference acceleration is calculated based on the Kalman filter algorithm. In the on-board control period when no target speed message is received, the reference speed used by the on-board controller is deduced based on the above estimated results. In consideration of the characteristics of target speed message delay and train response delay, a quasi-parallel reference speed tracking control strategy is designed. With Shanghai Metro Line 2 as an example, the estimated results of reference acceleration and the effect of train control under different operation level scenarios are analyzed. [Result & Conclusion] The above algorithm demonstrates that using the presented algorithm can overcome the problem of frequent switching of train control conditions caused by long cycle of target speed message and unfixed message interval, avoid the saturation of control commands and concave phenomenon of speed curve in the stair-like target speed tracking process with the compatible on-board system. It realizes the smooth control of train deceleration before the train enters the station, improves ride comfort, reduces train brake wear and saves traction energy consumption.

Keywords

• urban rail transit
• compatible on-board system
• stair-like target speed
• smooth tracking and control