A time-optimal aircraft-following model is introduced to address air traffic flow interference by velocity reduction. The objective function is set up as minimizing the recovery time during which the separation minima are not infringed and the separation of the air traffic flow returns to the initial separation at the terminal time. Pontryagin’s minimum principle is used to solve the optimum aircraft-following velocity control law. An analytical minimum safe following separation is also provided under the time-optimal control law. The simulation results show that the precision first-order tracking accuracy is achieved without losing the separation.
To deal with the inherent nonlinearity and open-loop instability of the electromagnetic suspension (EMS) system, a new nonlinear control method is proposed. The simulation results show that, for a PID controller, the overshoot of the system response to an airgap step disturbance is about 3 mm, and the transient time is 6 s; however, for the proposed nonlinear controller, there is no overshoot and transient time within 2 s. The proposed method has a faster response and stronger robustness. With a designed bi-DSP suspension controller, this nonlinear control method was implemented on the Shanghai Urban Maglev Test Line (SUMTL) to validate its effectiveness and feasibility.
