An Energy-Based Nonlinear Pressure Observer for Fast and Precise Braking Force Control of the ECP Brake

The inconsistent braking force will result in collision compacts between adjacent freight cars of heavy haul train, which utilizes ECP as brake system. Moreover, the rigid connection mode aggravates the negative effect. In practical applications, the brake pipe (BP) pressure sensor is used as the feedback in the closed loop brake force control of the ECP brake, but there is no sensor in the brake cylinder (BC), whose pressure is the control target, and these factors will contribute the longitudinal impacts among the freight cars. Therefore, an accurate and fast braking force control is extremely important for ECP brake. Firstly, as for the highly nonlinear ECP system of heavy haul train, an energy-based globally stable pressure observer for ECP brake is proposed. And then, according to the pressure of BC estimated by the observer, an enhanced sliding-mode control algorithm is applied to realize the fast and precise braking force control. Finally, experimental results are presented to demonstrate and validate effectiveness of the proposed observer and control algorithm.