Research Of The Robust Attitude Control For A Subminiature Unmanned Helicopter

Subminiature Unmanned Helicopter(SUH) has the advantage of the low cost,the small volume,the convenience for transportation,the small land for flying-off or landfall and hang in the small space. So it has the widely purpose in the military and civil fields. The dynamics of a SUH has the character of multivariable,nonlinear and strong coupling. So the SUH can be interfered with wind easily and hard to keep stable. The Flight Control System (FCS) is the pivotal part to realize autonomous flight and promote the practicability of the SUH and the attitude control is the key in the FCS. Robust control theory is one of the popular areas in the field of control engineering to deal with multivariable system and to improve the anti-noise ability. So the research of the robust attitude control for the SUH is very valuable.Foremost, clued by some overseas successful SUHs, the state-of-the-art of SUHs was studied, the frameworks and the characters of the FCSs were concluded and analyzed, and then the goal and the contents of the research were decided.From the view of the actual requirement, the whole scheme of system was designed on the thought of modularization, and the sensors,the microchip and data linker of FCS were chosen.The flight motion model of the SUH is the precondition of flight control laws design and the flight quality is also depending on the model. For the model of the SUH, the geostatic equation and aerodynamics equation was set up. At the same time, the main blade and the bell-hiller flybar were studied. Based on the above research and reasonable assumption,through the linearization of the nonlinear dynamics, the linear time-invariant attitude dynamics with physical parameters was obtained.To the unknown parameters of the above attitude model, a subspace based state space system identification method based on principal component analysis was carried out,which can identify the state space model of a plant with white noise and controller through orthogonal projection. And the range of the error of the parameters was also been estimated. Then the valid of the identified attitude model was testified. In order to apply the identification,the attitude model was been discretized firstly. Then the data processing of the flight data which to deal with the occasional bursts and outliers, missing data etc was processed to make sure that the data would be more reliable and correct.In general, the structure uncertainty or parameter uncertainty exist in almost systems for the tolerance between execution unit and control unit, and also the system was interfered with outer circumstances inevitably. So controller and analysis outcome of systems with precise mathematical models are always dissatisfied with project requirement. Aimed at the attitude model gotten form the identification, an approach for guaranteed cost control was theoretical derived for the system with the diagonally uncertainty for small noise circumstance,and the cost no more than a supremum. An approach for robust covariance control and another for which has limited input power was theoretical derived for the system with the diagonally uncertainty for noise circumstance which made the system has good steady performance and transient property. Then the worst instances were been defined for the guaranteed cost control and robust covariance control, and the simulation was theoretical derived and been done.On the basis of the above research, the hardware and software of the FCS and the Ground Control Station (GCS) was studied and developed then. With respect to the hardware of FCS, sensors module, remotely control/automatic control switch circuits and the main module were designed based on task sorting and the thought of modularization. With respect to the software of FCS, the task sorting, the task scheduling module and the communication protocols were designed. With respect to the GCS, founded on the analysis of the functional requirements of the GCS, the component programming method based on component object model was considered.Finally, the flight experiments are carried through by the autonomously hanging flight which is the worst flight state based on the FCS and GCS of this paper, the experiment results validate that the attitude is stable in flight under the action of FCS by analyzing the flight data.