Comparison of model reduction methods for very flexible aircraft

This paper deals with the model reduction methods for very flexible aircraft (VFA). Such aircraft is characterized by strong coupling between rigid motion and flexible motion, resulting in a very high order system for controll design. Recently released high-fidelity Vulture model of 707 order is chosen to be a typical example of VFA and is regarded as the reference model. Then three model reduction methods: balanced truncation method, balanced residual method and optimal hankel norm approximation are presented. Finally, numerical simulation is used to illustrate the characteristic of VFA and determine the best method for model reduction of VFA. In addition, the relationship between model error and model order is given. Both frequency domain and time domain analysis verify the reduced model of order 80 using balanced singular perturbation method is sufficient to maintain the accuracy of the full model.