Cooperative braking of urban rail vehicles with Koopman model predictive control

Abstract

Braking control of urban rail vehicles with multiple carriages is critical to ensure the safe operation of urban rails. However, existing decentralized braking control methods lead to the inconsistent speed and excessive coupler force among carriages, which compromises the operation safety of urban rails. To address this issue, a cooperative braking strategy is proposed for urban rail vehicles based on Koopman model predictive control method. First, a cyber‐physical model is established, where the physical layer characterizes the dynamic model of multiple carriages using the Koopman operator. The cyber layer represents the communication topology of carriages with graph theory. Second, a cooperative braking controller is designed with the distributed model predictive control method. An optimisation problem is formulated to minimize the speed inconsistency and relative displacement difference among carriages. Third, extensive simulations under various scenarios, including normal and extreme operating conditions, are conducted to verify the effectiveness of the proposed method. Simulation results show that, compared with the classical decentralized method, the proposed braking method reduces the average relative displacement by 78% while reducing the speed error by 29%.

Cooperative predictive set point modulation control of high‐speed trains

“…Cooperative control [8, 9] of multiple high‐speed trains allows high‐speed trains to operate at smaller intervals, which can effectively improve the traffic capacity of lines. The key of train cooperative control systems is to establish the train operation model [10], and design the corresponding cooperative control rule to guarantee the trains run with a synchronized velocity. In [11], the nonlinear resistance effects of high‐speed trains was considered and a distributed tracking control method is proposed to guarantee the velocity synchronization at the steady state.…”