模型阶次的辨识,各种模型参数辨识方法一般需要假定模型的结构已知，实际上在多数情况下这是不现实的。当没有模型结构的先验知识时，需要利用系统的输入输出数据来确定模型的结构。-Identification of various model parameters generally need to assume that the model structure is known, in fact, in most cases this is unrealistic. When no prior knowledge of model structure, the need to use the system input and output data to determine the model structure.