Robust flight control system design with multiple model approach

An approach that is introduced by combining the concepts of multiple models, LQR (Linear Quadratic Regulator), and proportional output feedback, is applied to robust flight control system design. Robustness of the control system is obtained with multiple models that represent uncertain dynamics. In particular, a delay element of uncertain delay time is proposed in order to introduce a robust multiple input control system, bandwidths of which can be assigned. The so-called loop shaping for MIMO systems is possible using this approach. The quadratic performance index that directly results based on the design objective makes the system design simple. Two numerical examples are shown. A simple example of a single input double integral system demonstrates the nature of this approach. The other example is for an automatic landing system for a transport type airplane. Bandwidth difference between the elevator and power control input is easily taken into consideration with the multi-model approach. Numerical examples demonstrate that robustness is increased using the multi-model approach compared with the standard LQR method.