During the ascent phase of a missile, a challenging problem occurs that blocks the construction of a high-precision attitude control scheme, which directly affects accurate modeling including disturbances: non-linearities of an actuator, rapidly time-varying parameters, un-modeled dynamics, etc. In order to improve the control performance, an active disturbance rejection control (ADRC) scheme, considering non-linear dynamics of the actuator and wind disturbance during the ascent phase, is proposed in this paper. An expand state observer (ESO) is planned to estimate and compensate the actuator’s non-linear dynamics, flight model uncertainties, and wind disturbance. Therefore, the complex non-linear time-varying control problem is simplified into a linear time-invariant control problem. The pitch attitude control system is controlled by the cascade method and ADRC controllers are designed for actuator close loop and attitude control loop, respectively. The simulation results show that ADRC has strong robustness under different dead-zones and external disturbances of the actuator. On the other hand, ADRC can effectively suppress the external atmospheric disturbance. Compared with the traditional gain-scheduling control scheme, the ADRC scheme can significantly reduce the overloading of the system and shows remarkable performance for tracking as well as wind resistance.

With the application of advanced composite materials in High-Aspect-Ratio wings (HARW), the randomness of structural parameters, such as elastic modulus and Poisson's ratio, is enhanced. Hence, in order to explore the whole picture of aeroelastic problems, it is of great significance to study the role of random structural parameters in aeroelastic problems. In this paper, the dynamic response of flexible HARW considering random structural parameters is analyzed. An aeroelastic model of a one-dimensional cantilevered Euler–Bernoulli beam considering aerodynamic forces acting on the wing is established based on Hamilton's principle. Adopted the idea of simplifying calculation, the effect of random structural parameters is analyzed. Then, considering the elastic modulus and torsional stiffness as continuously one-dimensional random field functions, and discretized by local method. The first and second order recursive stochastic nonlinear finite element equations of wing are derived by using perturbation method. Based on it, statistical expression of aeroelastic effects of the wing is derived. Monte Carlo method is adopted to verify the effectiveness of the method. Numerical simulations indicate that the method proposed can well mirror the statistical characteristics of aeroelastic response.

Friction nonlinearity, which is common in electromechanical actuator (EMA) systems, leads to undesired dynamic responses such as “flat top”, low-speed crawl, which brings challenges to high precision attitude control of flight vehicles. In order to improve the robustness of the actuator control system under friction nonlinearity, and suppress the chattering caused by high gain of sliding mode control (SMC), a composite SMC scheme based on modified extended state observer (MESO) is proposed. Nonlinear MESO is adopted for estimating the nonlinear friction dynamics, unmodeled disturbance, and external real-time load dynamics so as to compensate for their adverse effect. At the same time, in order to improve the robustness of EMA, and reduce the tracking error of the servo system, SMC is adopted to ensure the tracking error convergence in a finite time. The stability of the proposed method is proved, and the effectiveness is verified by simulations.

According to the characteristics of complex spatial mode of long booster clustered launch vehicle, it is not suitable to derive the dynamic equations based on the simplified model of single beam considering only core rocket. In this paper, the long booster clustered launch-vehicle is simplified to a multi-beam model considering core and boosters. Then, due to the high proportion of the liquid propellant in the total mass of the launch vehicle, on the basis of the multi-beam model, a dynamic equation considering the elastic deformation and the liquid sloshing is established. The dynamic characteristics of the launch-vehicle and the interaction between liquid sloshing and aeroelasticity are studied by simulation. Based on the multi-beam model, the connection types between the core and the booster rocket are simplified to an elastic connection. The influence of the connection on the dynamic characteristics of the launch-vehicle is discussed. The results demonstrate that the multi-beam model can more fully reflect the dynamic characteristics of the long booster clustered launch-vehicle, and the connection form between the core and the boosters also has an important effect on the liquid sloshing and the elastic deformation.

This paper focuses on the problem of the coupling between the rigid body mode and elastic mode caused by the light structure design and slender geometry of the hypersonic vehicle, and the influence of the liquid sloshing on the aircraft. In order to analyze the complex dynamics of hypersonic vehicle, the nonlinear dynamic model of a flexible vehicle is established in the case of the vehicle’s elastic deformation. The yields terms that produce nonlinear coupling between the elastic deflections, liquid sloshing and the rigid-body motion parameters are obtained by Lagrangian approach. Then, the equations are reduced to a linear set for stability analysis. Finally, some numerical simulations are given that reveal a destabilizing influence of elastic deflections and liquid sloshing at stability for a particular vehicle configuration.