针对未知系统中双控制器的设计问题，采用虚拟参考反馈校正方法，通过最小化由一组观测数据组成的L2 范数所构成的代价函数，达到直接设计控制器目的．联合前馈控制器分离出的固定部分和反馈控制器作为滤波器，对原输入/输出关系式进行重参数化，得到标准的预测误差辨识形式，在所得式中，对控制器未知参数矢量采用可分离迭代的非线性最小二乘法进行估算．文中还对算法的收敛性进行了理论分析，并通过仿真验证了所提方法的有效性．

In this paper,a method that minimizes the 2-norm-type cost function consisted of a set of observed data,namely the virtual reference feedback tuning,is employed to directly design a dual-controller for an unknown system.In this method,the fixed part decomposed from the feedforward controller is combined with the feedback controllerto form a filter,a normal formula of the prediction error identification is derived by re-parameterizing theoriginal input /output relationships,and a separable iterative nonlinear least square method is used to estimate theunknown parameter vectors of the controller.Moreover,the convergence of the proposed algorithm is theoreticallyanalyzed,and the effectiveness of the algorithm is finally verified by simulations.