In this paper, based on the advantages of Newtonian mechanics method, mixed coordinate method, and analytical mechanics method, the dynamic model of rigid-aeroelasticity-sloshing coupling is established for longitudinal vibration and liquid fuel sloshing, as well as the coupling between elastic deformation and liquid sloshing and their influence on the liquid rocket motion are analyzed. Considering the coupling effect between aeroelasticity and liquid sloshing, a new flutter analysis model is proposed, and the corresponding flutter analysis is carried out. First, the simplified model of the body and the liquid of the tank are established. By using Newtonian mechanics and analytical mechanics method, the nonlinear structural dynamic model considering the 3-D vibration and liquid sloshing is obtained. Second, influence of rigid-aeroelasticity, rigid-sloshing, aeroelasticity-sloshing, and rigid-aeroelasticity-sloshing coupling is simulated and analyzed. Finally, a new simplified model for the analysis of the flutter of the body is built by taking into account the impact of the liquid fuel sloshing. The results demonstrate that the elastic deformation and liquid sloshing change the motion characteristics of the rocket, and there is a strong coupling between the aeroelasticity and sloshing. Meanwhile, liquid sloshing has different effects on the flutter in all directions.

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.

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.

Since the missile dynamical system in the pitch plane is nonlinear, uncertain and non-matched, its integrated guidance and control is nontrivial. In order to cope with this problem, an adaptive back-stepping based sliding mode control algorithm is proposed in this paper. Firstly, the sliding surface of the virtual control variable is defined thanks to the strong robustness of sliding mode control. Secondly, it is highlighted that the calculation scales with the number of the virtual variables in back-stepping control. To deal with this problem, an adaptive sliding mode control is used to estimate the upper bound of the uncertainties and to simplify the control system design. The closed-loop stability has been proven based on Lyapunov theory. Finally, the simulation results have been reported to witness the validity of the algorithm, which show that the proposed approach can reject the target uncertainty and have a satisfactory control performance.

In order to simplify the design procedure of traditional neural network backstepping and improve the robustness and precision of control, an improved scheme is studied for a class of nonlinear systems. To avoid reconstructing virtual control inputs in each recursive step, RBF neural networks are utilized as approximators to estimate the desired feedback control of the whole system only. Meanwhile, the integral action of tracking error is introduced into the backstepping design procedure, which not only participates in updating the neural network weight, but also serves as a component part of the control input. This design may benefit the parameter tuning and make controller perform better sometimes. Based on the Lyapunov synthesis approach, theoretical analysis and simulation results are provided to show the feasibility of the improved scheme.

As an electromechanical drive system, nonlinear factors are unavoidable in electromechanical actuator (EMA). In this paper, elasticity of shaft and backlash nonlinearity are considered in the model, the effects of elasticity and backlash on EMA are analyzed. In order to suppress the vibration caused by nonlinearity and elasticity, A nonlinear control method based on backstepping method is proposed. The simulation results show that this method can eliminate the limit cycle oscillation (LCO) caused by backlash, and effectively suppress the vibration.