Tracking Control In Cruise Phase Of Hypersonic Vehicle With Input Saturation

Hypersonic vehicle(HSV) is a kind of aircraft flying at the speed of more than 5 times the velocity of sound. HSV works within the atmosphere, and it depends most on the aerodynamics to propel.Comparing with the regular aircraft, HSV features quality of high maneuverability and high speed. The research on HSV has become a hot domain,and the development level of HSV shows the power of national defense. However,just because of the features mentioned above, the HSV has the charteristics of strong nonlinearity,siginificant coupling a nd fast time-varying. Moreover,high quality of maneuverability means that great control input is needed, which can easily lead to input saturation. As a result, aircraft is instable. Therefore, it is necessary to consider the problem of input saturation.Based on reasonable assumptions and simplification,this article build the rigid model of HSV.It is clear that the states of the model are siginificantly coupling. After little perturbation to the model, It can be seen that the zero-poles of HSV are obviously different from the regular’s, especially, the HSV has the unstable pole, which leads to the severe degradation to the quality of the control systemThe method of feedback linearization is widely used to deal with the high-oder or siginificantly coupling systems like the HSV. This article expounds the concept of feedback linearization, and then applies it to the HSV model by differentiating state V three times and state h four times. At last, the inputs are explict in the equations, which simplies the control system design.For the model treated through feedback linearization,the LQR controller and Sliding mode controller are designed. The LQR controller is easy to design and adjust parameter.As for th e sliding mode controller, under the prerequisite of no saturation, classic sliding mode surface is adapted with the new reaching law,which guarantees the states are fast converged to the sliding mode surface without singularities. At the same time, the sliding mode controller achieves satisfactory tracking performance.When facing the problem of input saturation, anti-saturation controller is designed to limit the input amplitude. This method obtains good result.At last, an adaptive backstepping method is presented for the HSV longitudinal model.First, the states are divided to two parts:the fast subsystem and slow subsystem. Second,with the prerequisite of no saturation,adaptive backstepping controllers are designed respectively for the new subsystems with update laws, which ensures the robustness of the system.As a result,the controllers achieve satisfactory tracking performance. In this chapter,a kind of signal is added to the controller to solve the input saturation. The new controllers achieve the sam e tracking performance,and solve the input saturation at the same time.