• A high-order internal model based iterative learning control scheme for nonlinear systems with time-iteration-varying parameters

      Yin, Chenkun; Xu, Jian-Xin; Hou, Zhongsheng (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2010)
      In this technical note, we propose a new iterative learning control (ILC) scheme for nonlinear systems with parametric uncertainties that are temporally and iteratively varying. The time-varying characteristics of the parameters are described by a set of unknown basis functions that can be any continuous functions. The iteratively varying characteristics of the parameters are described by a high-order internal model (HOIM) that is essentially an auto-regression model in the iteration domain. The new parametric learning law with HOIM is designed to effectively handle the unknown basis functions. The method of composite energy function is used to derive convergence properties of the HOIM-based ILC, namely the pointwise convergence along the time axis and asymptotic convergence along the iteration axis. Comparing with existing ILC schemes, the HOIM-based ILC can deal with nonlinear systems with more generic parametric uncertainties that may not be repeatable along the iteration axis. The validity of the HOIM-based ILC under identical initialization condition (i.i.c.) and the alignment condition is also explored.
    • Modified iterative-learning-control-based ramp metering strategies for freeway traffic control with iteration-dependent fctors

      Hou, Zhongsheng; Yan, Jingwen; Xu, Jian-Xin; Li, Zhenjiang; Beijing Jiaotong University, Beijing, China (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2012)
      For a freeway traffic system with strict repeatable pattern, iterative learning control (ILC) has been successfully applied to local ramp metering for a macroscopic freeway environment by formulating the original ramp metering problem as an output tracking, disturbance rejection, and error compensation problem. In this paper, we address the freeway traffic ramp-metering system under a nonstrict repeatable pattern. ILC-based ramp metering and ILC add-on to ALINEA strategies are modified to deal with the presence of iteration-dependent parameters, iteration-dependent desired trajectory, and input constraints. Theoretical analysis and extensive simulations are used to verify the effectiveness of the proposed approaches.