一种考虑系统不确定性估计的重载列车最优黏着控制

An optimal adhesion control of heavy haul train considering system uncertainty estimation

重载列车在运行时,黏着条件容易受到不良的天气状况或轨面状态影响,会导致列车无法有效发挥牵引力。为了解决重载列车在运行过程中因黏着条件恶化导致无法有效发挥牵引力的问题,提出一种考虑系统不确定性估计的离散积分滑模控制方法,该方法通过对最优蠕滑速度的跟踪控制,实现重载列车的最优黏着控制。由于黏着系数在实际情况中难以测量,所以针对此情况设计串联滑模观测器对黏着系数进行观测估计。采用带遗忘因子的最小二乘法估计出黏着特性曲线斜率,并根据梯度下降算法得到最优蠕滑速度。以最优蠕滑速度和实际蠕滑速度作为控制系统输入,以牵引电机转矩作为系统输出,利用一步延迟估计方法估计系统的不确定性,据此设计离散积分滑模控制器控制电机转矩使蠕滑速度始终稳定在最佳蠕滑速度处。仿真实验结果表明:设计的考虑系统不确定性估计的离散积分滑模控制方法实现了对最优蠕滑速度的跟踪控制,并且与离散积分滑模控制方法相比,系统跟踪误差更小且具有更高的控制精度。说明采用的方法不仅能够补偿系统的不确定性和抑制抖振现象,而且还能实现对最优蠕滑速度的高精度跟踪控制,达到使重载列车牵引性能最优的目的。

During the operation of heavy-haul train,the adhesion condition is easily affected by bad weather and track surface condition,which may lead to the failure of the train to effectively exert the traction force.In order to solve the problem that the traction force of heavy haul trains cannot be effectively exerted due to the deterioration of adhesion conditions during operation,a discrete integral sliding mode control method considering the estimation of system uncertainty was proposed.The goal was to achieve optimal adhesion control of the heavyhaul train by tracking the optimal creep speed.First,since the adhesive coefficient was difficult to measure in the actual situation,the cascaded sliding-mode observer was designed to obtain the observation of the adhesion coefficient.Second,the recursive least squares method with forgetting factor and the gradient descent method were used to determine the optimal slip velocity.Finally,the optimal creep speed and the actual creep speed were taken as the control system inputs and the traction motor torque as the system output.The one-step delay estimation method was used to estimate the system uncertainty,and a discrete integral sliding mode controller was designed to control the motor torque so that the creep speed remained stable at the optimal creep speed.The simulation results show that the designed discrete integral sliding mode control method considering the uncertainty estimation of the system achieved the tracking control of the optimal creep speed.As compared with the discrete integral sliding mode control method,the system has smaller tracking error and higher control accuracy.It shows that the method can not only compensate the uncertainty of the system and suppress chattering,but also realize the high-precision tracking control of the optimal creep speed so as to optimize the traction performance of the heavy-haul train.