The active sidestick is a crucial control device that can adjust the flight attitude of an aircraft. In the automatic flight mode, the active sidestick follow-up function tracks the control commands from the flight controller in real-time to enhance the pilot's perception of the aircraft's flight status, thereby effectively improving flight safety. However, unknown disturbance torques in the system can degrade the tracking accuracy of the active sidestick. To address this challenge, a control method based on composite nonlinear feedback and adaptive integral sliding mode is proposed for the follow-up control of the active sidestick. This method integrates an integral sliding mode control algorithm and the composite nonlinear feedback control algorithm, where the composite nonlinear feedback control effectively improves the steady-state performance of the active sidestick system, and the adaptive integral sliding mode control effectively restrains unknown system disturbances. Extensive experimental results show that the proposed improved active sidestick follow-up control algorithm can reduce the adjustment time by approximately 41% and the steady-state error by about 93.6% compared to the previous composite nonlinear feedback control algorithm. Furthermore, under disturbance conditions, the improved follow-up control algorithm can reduce the adjustment time by about 79% compared to the traditional PID algorithm. This demonstrates that the designed improved active sidestick follow-up control algorithm can significantly enhance the system's control accuracy and response performance, and possess excellent disturbance rejection capabilities.

For missile's precision guidance task, an optimal leading angle sliding mode control algorithm based on GA-BP (genetic algorithm-back propagation) is proposed, in which the sliding mode control is improved segmentally. Aiming at the problem of the fixed leading angle sliding mode control depending on a leading angle value, but it is difficult to be predefined, a GA-BP neural network is developed and used to estimate the optimal leading angle for a specific task model. Subsequently, based on the estimated value of remaining time, a piecewise sliding mode reaching law is designed, which lead to a segment-improved sliding mode control algorithm that further enhances robustness during the missile guidance process. And then the complete optimal leading angle segment-improved sliding mode algorithm based on GA-BP is formed. After the algorithm is simulated and analyzed, Simulation results indicate that, compared with the fixed leading angle sliding mode control algorithms, the proposed algorithm can reduce task time approximately 5% in average, and the overload around 12%. As it can reduce the task time by up to 30% in the maximum, so it has a higher superiority.

To study the influence of the composite microburst wind field on the cruise phase of a light and small fixed-wing unmanned aerial vehicle (UAV), in this paper, a Dryden atmospheric turbulence model and a microburst model are constructed, and after fusing them, a composite microburst wind field model is created. Take a specific electric-powered UAV as the object of study and carry out a six-degree-of-freedom rigid body ballistic model simulation analysis, the simulation results show that the newly established composite wind field model has better randomness and typical wind shear characteristics and it can effectively depict the actual composite microburst wind field distribution and change. Under the influence of this composite wind field, the UAV has experienced a significant loss of height, and when the central induced velocity is between 10~25 m per second, the loss of height reached 168~537 m. Furthermore, the flight parameters of UAV, including flight duration, angle of attack, sideslip angle, and power margin, have changed in different degree.

In order to provide reference for the analysis on exterior ballistic environment of fuze, FLUENT software is applied to numerically simulate the aerodynamic characteristics of a large caliber dynamic imbalance spin-stabilized projectile with base cavity, and corresponding aerodynamic characteristics of the whole trajectory are obtained. The function relationship of aerodynamic characteristics, dynamic imbalance angle with Mach number of the projectile is fitted 1stOpt software. The influence exerted by dynamic imbalance angle on drag coefficient is small and within 2% lift coefficient, overturning moment coefficient and polar damping moment coefficient are positively linearly correlated with dynamic imbalance angle of the projectile while Magnus force coefficient and Magnus moment coefficient are negatively linearly correlated with dynamic imbalance angle of the projectile. When dynamic imbalance angle is large (such as 1°), polar damping moment coefficient will increase 2~4 times compared with that dynamic imbalance angle is zero.

A sliding mode robust control strategy based on an adaptive first-order sliding mode disturbance estimator and a two-phase combined function reaching law is proposed for the control problem of uncertain quadrotor aircraft system. The quadrotor aircraft system is divided into two fully-actuated subsystems and two under-actuated subsystems, and the sliding surface of each subsystem is constructed by adopting proper sliding surface design method. A continuous adaptive first-order sliding mode disturbance estimator is adopted to online approximate the uncertainties of each subsystem, and a two-phase combined function reaching law that can dynamically adapt to the variation of the sliding surface is used to sequentially design the control amount of the fully-actuated subsystems and the under-actuated subsystems. The stability of the closed-loop control system and the convergence time of the sliding surface of the control system are theoretically analyzed. The simulation test results verify the robust control performance and controller chattering reduction ability of the proposed sliding mode control strategy.

Accurately and quickly detecting military targets in complex scenarios has important military value in perceiving battlefield situations, conducting reconnaissance and early warning analysis, and providing precise missile guidance. A multi-scale object detection algorithm AEM-YOLOV5 (AFPN-EMA-MPDIoU-YOLOV5) based on improvements to YOLOV5s is proposed to address the issues of poor feature learning ability, low detection accuracy, and high computational complexity in existing algorithms. Firstly, the AFPN asymptotic feature pyramid network is introduced into the neck network to gradually fuse the detailed information at the bottom of the image and the high-level semantic features at the top, enhancing the network feature fusion effect. Secondly, an EMA attention mechanism module is added before each detection branch to aggregate pixel level features across spaces, improving the level of attention to multi-scale targets in complex scenes. Finally, MPDIoU is used to replace the original C_IoU bounding box loss function in YOLOV5, solving the problem of C_IoU degradation when the predicted box aspect ratio is the same but the absolute value is different, making the regression results more accurate. The experimental results show that the improved algorithm performs well on the RSOD dataset, P_mAP50 reaches 94.5%, FPS reaches 42 frame/s, and model size is 14.8 MB. Compared with existing algorithms, the improved algorithm significantly improves its performance, meets the real-time requirements of military target detection, and the model is lightweight.

Aiming at the problems of large errors and insufficient adaptation to meteorological changes in existing ballistic drop prediction methods, a ballistic dataset containing meteorological conditions is established and a CNN-BiLSTM-BiGRU ballistic drop prediction method based on a self-attention layer is proposed in this paper. The self-attention layer and residual connection are introduced into the constructed combined model to strengthen the model's ability to dynamically focus on the information at different moments when processing the input sequences, and to alleviate problems such as gradient explosion in the network. It also uses the input representation of multi-dimensional time series data to reduce the ballistic drop prediction error by combining multiple information such as historical ballistic trajectory data and target characteristics. The simulation results show that the prediction effect of the CNN-BiLSTM-BiGRU network model based on the self-attention layer is better than the other models, and the maximum error of the range prediction accounts for 0.156% of the true value, and the maximum error of the lateral deviation prediction accounts for 5.904% as of the true value. The method provides an important reference for the field of ballistic drop prediction.

Aiming at the problem of multi-missile cooperative attack on enemy air targets, a multi-missile and multi-constraint three-dimensional cooperative guidance method based on sliding mode control theory and artificial potential field method is deduced. Firstly, according to the relative motion of the missile and the target, a three-dimensional non-linear model of the relative motion between the missile and the target was established in the line-of-sight coordinate system. Then, taking the remaining flight time of multiple bombs as the coordination variable, based on the finite time consistency theory, the guidance law of the direction of sight of multiple bombs is designed, which realizes the coordinated attack on the target. On this basis, the normal direction of sight guidance law of multi-missile is designed through the sliding mode control theory, so that the multi-projectile can hit the enemy target at a given line of sight angle, and according to the convergence characteristics of the sliding mode surface, the parameters are adaptively updated to reduce the sliding mode parameter selection complexity. In addition, considering the difficulty in obtaining target maneuver information, an expanded state observer is designed to efficiently predict target acceleration information. Finally, combined with the idea of artificial potential field method, a multi-missile obstacle avoidance control command is designed to effectively avoid constraints such as avoidance zones during multi-missile flight. The simulation results verify the effectiveness of the proposed guidance method.

The aerodynamic loads, multi-body motion, and contact collisions involved in the separation process of rocket and missile launches are key factors affecting the reliability of launch separation. To adopt numerical methods for analyzing such coupled states of flow and motion, an in-depth study is conducted on the launch separation flow and collision coupling model based on a virtual contact approach. The coupling model starts from a transient flow field numerical model, that is introduced a dynamics model concerning the six degrees of freedom (6-DOF) multi-body motion, subsequently, a contact dynamics model characterized by virtual contact is used to examine the multi-body contact collision loads to obtain the coupled states of object motion and flow under various loads. The analysis of application examples shows that the virtual contact method can effectively simulate the coupled state of flow, motion, and collision during launch separation and the method can provide a reference for similar analyses.

The temperature of the rocket control cabin is predicted by aerodynamic heating and structural thermal response calculation, and verified by flight test. Firstly, the ballistic feature points are selected and transition is judged. The aerodynamic thermal environment of the rocket flight is obtained by the combination of computational fluid dynamics and engineering calculation methods. Then, based on the finite difference method, the temperature response of the heat protection structure at the rocket control cabin is obtained. Finally, the numerical calculation results are compared with the flight test data. The numerically predicted maximum temperature of the inner wall of the rocket control cabin is 5.6% higher than the flight test value, and the numerical prediction method in this paper can be used in the thermal protection design of the rocket.

The reliability and safety of the unlocking device in a missile launcher are much more important to the launch system of an aircraft and they even influence its flight mission. In order to investigate the unlocking performance of storage and transportation device under the accidental vehicle ignition condition, the longitudinal lock in the typical lever locking mechanism of the launcher is taken as the objective in this paper. The nonlinear explicit numerical test method is adopted to establish a fracture model for the longitudinal lockto analyze its unlocking performance alongwith proof test. The results show that under the action of axial thrust generated by the motor, the end thread of the bolt is damages and failure, and the outlet is extruded to reduce the contact between each other, so that the unlocking function is finally realized according to the fracture of the longitudinal lock. Based on the numerical experiments, the critical force for the longitudinal lock is 27 kN, and the safety margin under actual working condition is 11%. The reliability of numerical experiment have been verified by using a simulated missile loading test to get actual fracture condition of the longitudinal lock. The results can provide theoretical reference for the safety analysis of the storage and transportation device.

In order to study the influence factors of vertical bayonet-chamber of heavy calibre naval gun projectile, a study is conducted using explicit dynamic finite element numerical simulation and multi-body dynamic simulation, combined with experimental data analysis and comparison. The influence of various factors on bayonet-chamber is obtained by analyzing bayonet-chamber velocity, copper strip width, copper strip outer diameter, dynamic friction coefficient, and the relationshipe between entry chamber velocity and bayonet-chamber velocity. The results are as follow: the established explicit dynamic numerical simulation method can effectively simulate the process of bayonet-chamber, and the simulation results are consistent with the experimental results. The main factors affecting the bayonet-chamber depth and force are the bayonet-chamber velocity and copper strip width, while the bayonet-chamber overload depends on the bayonet-chamber velocity. To ensure the bayonet-chamber reliability under maximum deviation attitude of projectile, the entry chamber velocity should not be less than 6.35 m/s.

In order to study the low energy impact resistance of re-entrant star-shaped (RES) and re-entrant circular star-shaped (RECS) honeycomb sandwich panels with negative Poisson ratio, a finite element model of honeycomb sandwich panels with composite laminates and ABS honeycomb is established by using commercial software ANSYS/LS-DYNA. Impact response of the composite sandwich panels with RES honeycomb and RECS honeycomb is analyzed numerically at low impact energies of 10 J,15 J,30 J. In this paper, the impactor displacement versus time curves、contact force versus time curves and energy absorption ratio of sandwich panels under different impact conditions are analyzed and compared. The simulation results show that under the same impact conditions, the damage depth of RECS honeycomb sandwich panels is greater than that of RES honeycomb sandwich panels, and the difference is more obvious when under in-plane impact. In addition, the impactor has a lower rebound speed after impacting RECS honeycomb sandwich panels, that is, the RECS honeycomb sandwich panel has a higher energy absorption ratio. According to the above results, it is concluded that RES honeycomb sandwich panel has better low energy impact resistance than RECS honeycomb sandwich panel, but the latter has better energy absorption performance.

For the segmented combustion instability phenomenon of slender solid rocket motors in the ground test, it can obtained the distribution range of pressure oscillation frequency in the combustion chamber by mean of acoustic cavity frequency analysis, analyzing the main factors of two-stage combustion instability from a perspective of acoustic-vortex coupling and propellant combustion response. Then through comparison experiment, comparing the combustion instability of the motor with the same grain configuration and different propellant formulations and combiningewith the acoustic cavity mode of the combustion chamber at the initial, middle and end time and the flow field vortex structure computation of the combustion chamber and the pressure coupled response function test results of the T-burner, the conclusion is that the combustion instability phenomenon at the initial stage of the motor operation is due to the fact that the vortex shedding frequency caused by the grain configuration is close to the frequency of the acoustic field of the chamber to generate coupling gain and induce the pressure oscillation. At the end of the operation of the motor, the combustion instability frequency is different from the initial frequency range, and there are frequency multiplication characteristics, the instability is caused by the combustion response of the propellant. The analysis unfolds from the two-stage combustion instability in the ground test andprovids a reference to optimize solid rocket design and effective avoidance of such problems in engineering design.

Solid rocket engine nozzle throat liner needs to withstand the ablation, erosion of high temperature and high-pressure gas and it nozzle throat diameter ablation rate has a high probability being non-linear during the whole working process. At present, research about nozzle ablation both domestic and abroad is mainly focused on numerical simulation analysis and ablation test of the nozzle body, however, there's a lack of investigation on the link between the nozzle ablation process and the function of solid rocket motor. This paper is based on the differential evolution algorithm and radial basis function neural network, and established a method for calculating the ablation rate of the nozzle throat diameter based on the test curve of solid rocket motor. Based on the ground static test results of solid rocket motor, the curve of nozzle throat diameter ablation rate changing with motorworking time was obtained. The results showed that the ablation rate of the nozzle throat diameter was small in the early stage of the motor operation, and gradually increased with the increase of the working time, as the temperature of the nozzle throat increased, this caused the ablation rate increased, after a period of time, the temperature of the throat liner became constant, and the nozzle ablation rabe is maintained at 0.2 mm/s. And after the ablation of the surface of throat liner was fully completed, the inner surface was exposed; the ablation rate would increase again.

The quality of explosive charge is a key factor affecting the performance of artillery weapons, and the explosive charge is often a mixture of powders. To improve the quality of cylinders made by a mixture of metal and non-metal powders, the mechanical behavior of the cylinders was described using continuum plasticity theory, the Shima-Oyane model and the Ogden model were employed as the material constitutive models for the cylinders and the rubber sleeve, respectively. And a simulation model for the isostatic pressing of cylinders was developed utilizing the nonlinear finite element software MSC.Marc. Based on the simulation model, the forming mechanism of cylinders was explored, and a comparative study was conducted on the influence of isostatic pressing process parameters on the forming quality of the cylinders. The results indicated that the simulation model could effectively reflect the forming characteristics of the cylinders. The maximum pressure and it’s holding time of isostatic pressing were the key factors that influenced the quality of the cylinders. When the pressure was set at 240 MPa and the holding time exceeded 400 s, the overall relative density of the cylinders reached above 97%, with the density distribution difference was below 0.5%. The results of the isostatic pressing experiment verified the accuracy of the simulation analysis results. The cylinders with approximate length-to-diameter ratios of 5∶1 achieved a higher process standard and satisfied the process requirements.

For the uncertainty of adaptation model, various nonlinear factors and diversity and complexity of operational environment the electrical actuator concerned, using velocity loop and position loop to realize a general robust control method is put forward. The design of the velocity loop controller adopts the principle of pole-zero cancellation to realize reconfiguration of the system pole and ensure the performance of the velocity loop is good and keep stable consistently. The position loop controller uses mixed sensitivity optimization design method to meet the requirement of the system robust stability, as well as ensure the control performance of the loop system. It also uses the balanced truncation method in the model reduction to remove the degree of freedom which contribute less to the system response and reserve the dominant mode, ensuring system performance and simplifying the position controller. By concrete design simulation verifying, the system is not only completely meet the performance characteristics, but also has better robustness. When the rotational inertia converted onto motor axis changes 2 to 6 times, using second order to fifth order position controller simulating, the high frequence in the position close loop Bode diagram of 4 kinds of controller changes slightly and the bandwidth is better than 20 Hz. The position loop unit step response is without overshoot and the ascent stage have difference; the adjustment time is better than 50 ms.