Consistent Total Traction Torque-Oriented Coordinated Control of Multimotors with Input Saturation for Heavy-Haul Locomotives

In the coordinated control of multiple motors for heavy-haul locomotives, the input value for a motor often exceeds its maximum allowable input value, resulting in the saturation problem. A traction total-amount coordinated tracking control (TACTC) strategy is proposed to address the input saturation of heavy-haul locomotives driven by multiple motors. This strategy reduces control input and suppresses input saturation. First, a multimotor traction model with uncertain parameter perturbations and external disturbances was established. Next, a sliding-mode disturbance observer (SMDO) was designed to reduce the sliding-mode switching gain, thereby decreasing the control input. An auxiliary anti-windup (AW) system was used to weaken the effect of input saturation on tracking performance. Then, the observed value and auxiliary state were fed back to the sliding-mode controller to design a TACTC protocol and ensure that the total amount of traction torque follows the desired traction characteristic curve. Finally, the Matlab/Simulink simulation and RT-Lab semiphysical experiment results show that the proposed strategy can effectively suppress the input saturation problem of multimotor coordinated control.

Integration of ZiYuan-3 Multispectral and Stereo Data for Modeling Aboveground Biomass of Larch Plantations in North China

Data saturation in optical sensor data has long been recognized as a major factor that causes underestimation of aboveground biomass (AGB) for forest sites having high AGB, but there is a lack of suitable approaches to solve this problem. The objective of this research was to understand how incorporation of forest canopy features into high spatial resolution optical sensor data improves forest AGB estimation. Therefore, we explored the use of ZiYuan-3 (ZY-3) satellite imagery, including multispectral and stereo data, for AGB estimation of larch plantations in North China. The relative canopy height (RCH) image was calculated from the difference of digital surface model (DSM) data at leaf-on and leaf-off seasons, which were extracted from the ZY-3 stereo images. Image segmentation was conducted using eCognition on the basis of the fused ZY-3 multispectral and panchromatic data. Spectral bands, vegetation indices, textural images, and RCH-based variables based on this segment image were extracted. Linear regression was used to develop forest AGB estimation models, where the dependent variable was AGB from sample plots, and explanatory variables were from the aforementioned remote-sensing variables. The results indicated that incorporation of RCH-based variables and spectral data considerably improved AGB estimation performance when compared with the use of spectral data alone. The RCH-variable successfully reduced the data saturation problem. This research indicated that the combined use of RCH-variables and spectral data provided more accurate AGB estimation for larch plantations than the use of spectral data alone. Specifically, the root mean squared error (RMSE), relative RMSE, and mean absolute error values were 33.89 Mg/ha, 29.57%, and 30.68 Mg/ha, respectively, when using the spectral-only model, but they become 24.49 Mg/ha, 21.37%, and 20.37 Mg/ha, respectively, when using the combined model with RCH variables and spectral band. This proposed approach provides a new insight in reducing the data saturation problem.

Adaptive Tracking Constrained Controller Design for Solid Oxide Fuel Cells Based on a Wiener-Type Neural Network

In order to solve the control problem of the solid oxide fuel cell(SOFC), a novel adaptive tracking constrained control strategy based on a Wiener-type neural network is proposed in this paper. The working principle of SOFC is introduced, and the dynamical model of SOFC is studied. Besides, a Wiener model formulation for SOFC is proposed to approximate the nonlinear dynamics of the system, and an adaptive Wiener model identification method is utilized to identify the parameters of the model. Moreover, an adaptive exponential PID controller is designed to keep the stack output voltage stable. Meanwhile, the saturation problem is considered in the paper including input magnitude and rate constraints. Additionally, an anti-windup compensator is employed to eliminate the abominable influence of the saturation problem. Then, the stability of the control plant is analyzed and proven via the Lyapunov function. Finally, the simulation based on the MATLAB/Simulink environment is carried out, and the conventional PID controller is added and simulated as a contrast to verify the control performance of the proposed control algorithm. The results indicate that the proposed control algorithm possesses favorable control performance when dealing with nonlinear systems with complex dynamics.

Finite Saturation for Unirational Varieties

We import ideas from geometry to settle Sarnak’s saturation problem for a large class of algebraic varieties.

Anti-Windup Variable Parameter PD Controller Design for Ballistic Missile

The conventional PD controller could cause the saturation problem of ballistic missile actuators. A design method of anti-windup variable parameter PD controller was proposed. The proportional coefficient and derivative coefficient were designed to be Gauss functions of system tracking error. Both were small when tracking error was big; whereas both increased as the tracking error decreased. This method not only restrained effectively the saturation problem, but also produced enough control force to drive system outputs to track their commands speedily. The control effect of anti-windup variable parameter PD controller was compared with that of the conventional PD controller in the numerical simulation. The simulation results show that the anti-windup variable parameter PD controller has better control effect.