Small Scale Unmanned Aerial Vehicle Frequency Domain Modeling Based On Coupling

Small Scale Unmanned Aerial Vehicle (UAV) has a lot of merits over other normal scale helicopter. It is very small, agile and easy to operate, good performance in hover flight, as well as good cost performance. It is widely used in the military and civil fields, such as using for reconnaissance and surveillance in war, for extinguishing fire, spraying pesticides. Many institutions and colleges in the world are doing research on it.The model of the UAV is very important for controlling the UAV precisely without man. There are a lot of methods to build the model for the small scale UAV. In this thesis, we consider the coupling relation between inputs, for the coupling influences between inputs can impact greatly on the performance of the small scale UAV. We use the multiple inputs and multiple outputs (MIMO) frequency analysis, multiple inputs and single output (MISO) frequency analysis, then identifying the parameters that we need in the state space.The frequency domain identification is based on the first principle modeling of the UAV. Firstly, the model structure of the UAV should be built according to the physical rules. Some of the parameters can be determined just from the measurement and calculation, but some parameters cannot be obtained from physical method, we use the frequency identification to estimate these parameters. During the identification process, the cost function is very important to determine the value of the parameters. We use the pattern search method to optimize the cost function. So the initial value of these parameters should be determined previously, we use single input single output (SISO) to get the initial value in this paper.After identifying the value of the parameters, the verification in time domain has been done, and the results can meet the requirement that we set up previously.