Tham khảo tài liệu 'frontiers in adaptive control part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | A New Frequency Dependent Approach to Model Validation 41 As a conclusion the model G can be accepted as a good approximation of the plant G up to frequency rad sec. For higher frequencies the mismatch between model and plant is present up to the input bandwidth . 3 rad sec . It should be mention that this result is input dependent. However the results obtained up to now can serve as a guideline to design new input signals with suitable frequency contents for new identification steps . high energy around the frequencies were a significant error exists that is between rad sec and 3 rad sec . 3. Control Oriented Model Validation Model validation theory is aimed towards checking the model usefulness for some intended use. Thus the model validation procedure should take into account the model use for example control design or prediction purposes. It is recognized in Skelton 1989 that arbitrary small model errors in open loop can lead to bad closed loop performance. On the other hand large open loop modelling errors do not necessarily lead to bad closed loop performance. As a result the model accuracy should be checked in such a way that the intended model use is taken into account in the model validation procedure. An important aspect in the validation procedure to take into account is the intended model use and the validation conditions. In fact validation from open loop data can provide a different result that validation with closed loop data. Furthermore it is completely different to validate an open loop model than to compare two closed loops the one with the model and the real one See for example Gevers et al. 1999 . This result points out the importance of the information that is being validated. In order to consider the model intended use in the validation procedure the conditions for data generation must be considered. In the following subsections different structures are proposed in order to compute the residuals and it is shown that they have .
