As cislunar space missions transition from exploration to long-term habitation and resource development,there is an escalating demand for positioning,navigation and timing (PNT) technologies characterized by superior autonomy,high precision and robustness.To address the fragmented technologies and insufficient resilience in current systems,this paper first identifies four core challenges for cislunar space PNT:the uneven distribution of ground-based tracking,telemetry,and command (TT&C) infrastructure,the poor geometry and severe signal attenuation of GNSS space service volume (SSV),the low accuracy of celestial navigation,and the lack of a mature cislunar navigation constellation.A holistic intelligent PNT technical framework is constructed from three critical dimensions:(1) intelligent navigation perception and multi-source data fusion,(2) adaptive decision-making with fault tolerance,and (3) resilient earth-moon collaborative architecture.Furthermore,the core implementation paths and coupling mechanisms are clarified.The developement trends,including multimodal large models and edge computing,are also discusses,and the strategic recommendations for future development are proposed.Results demonstrate that this integrated architecture can provide mission-critical support for China’s next-generation comprehensive PNT systems,specifically catering to the high-reliability requirements of establishing a lunar research station and conducting the manned lunar landings.
To further improve the prediction accuracy of solid rocket motor performance a parameter-model coupling-based predictive method for the internal ballistic performance of solid rocket motors is proposed.Firstly,the key factors influencing the prediction deviations are identified by analyzing the discrepancies between the predicted results of the classical zero-dimensional internal ballistic model and the actual motor operations.Secondly,in consideration of the characteristics of these factors,the prediction method is adjusted by using the undetermined parameters and the performance correction models to account for their respective effects.Based on this,a coupled prediction framework integrating both approaches is established.Finally,the internal ballistic performance is predicted and analyzed based on test data by taking the precise performance prediction problems of single-chamber single-thrust and single-chamber dual-thrust solid rocket motors as examples The results indicate that the proposed method significantly enhances the prediction accuracy of macroscopic internal ballistic parameters such as thrust and chamber pressure,while also enabling the precise estimation of mesoscopic parameters including burning surface area,nozzle throat diameter,and propellant burning rate.The prediction deviations for thrust and chamber pressure remain within 1%,and the prediction deviation for mass flow rate remains within 0.1%,thereby supporting comprehensive analysis of the engine's operational process.
A class of intelligent cooperative differential game guidance problems is investigated for multiple vehicles and manuvering targets.In particular,a leader-follower high-order nonlinear guidance model is established based on the master-slave cooperative guidance structure,and an intelligent cooperative optimal guidance strategy is developed via differential games.An evaluation neural network is established based on the adaptive dynamic programming (ADP) algorithm for self-learning and solving the guidance method online.The stability of the closed-loop system as well as the convergence of evaluation network weights are proved by applying the Lyapunov stability theory and the invariant set principle.Finally,the effectiveness of the method is verified through simulation,where the maximum miss distance and time error of multiple vehicles are less than 0.1m and 0.5s,respectively,demonstrating the accurate cooperative attack on the maneuvering targets.
The traditional interference suppression algorithms suffer from the shortcomings of relying on the accurate estimation of interference parameters in complex electromagnetic environments,needing the separate processing strategies for different types of interference,and weak generalization ability,This paper proposes a U-Net-based interference suppression algorithm using time-frequency image input.The proposed algorithm leverages the advantages of U-Net in image feature extraction and end-to-end learning by taking the short-time Fourier transform time-frequency image of the received signal as network input.The precise localization and effective suppression of interference components are achieved by using an encoding-decoding structure with skip connections,while preserving the original features of the target signal to the greatest extent.The proposed algorithm is compared with the conventional frequency-domain suppression methdod and the residual network-based suppression method in terms of four typical weak interferences,namely single-tone,multi-tone,narrowban and linear frequency modulation (LFM) interferences.The results show that the proposed U-Net-based algorithm exhibits an optimal bit error rate performance under different types of interference.It achieves approximately 1dB performance gain compared to traditional algorithms and about 0.5dB improvement over the residual network,and maintains stability under signal-to-interference ratios of 0dB and 5dB,thus verifying the strong robustness and good generalization of the proposed algorithm in weak interference environments.
Fort the tracking control problem of quadrotor unmanned aerial vehicles (UAVs)under the conditions of parameter uncertainties and external interference,an adaptive anti-saturation and anti-singularity appointed-time prescribed performance control method is proposed.Firstly,an adaptive anti-saturation and anti-singularity appointed-time prescribed performance function is designed.The transient and steady-state performance requirements of the system are achieved by selecting the design parameters of this function,ensuring that the tracking errors converge within any appointed time Tρ.The actuator saturation is effectively avoided by adjusting the design parameter b without additional anti-saturation compensators.Secondly,an adaptive adjustment term is designed to ensure that the tracking errors are always constrained within the preset range,thereby avoiding the singularity problems caused by sudden disturbances in the system.Moreover,the issues of system parameter uncertainties and unknown external disturbances ingeniously resolved using the adaptive method.Subsequently,an event-triggered control mechanism is proposed to reduce the communication and computation burdens and decrease the system energy consumption.Finally,the effectiveness of the designed control method is proved based on the Lyapunov stability theory,and the effectiveness and superiority of the proposed control algorithm are verified through simulation.
Hypersonic missiles,unmanned combat aerial vehicles,and other highly maneuverable targets possess maneuverability comparable to that of interceptors,where the interceptor's maneuverability does not exceed 1.2 times that of the target.The terminal acceleration is easily saturated when applying the traditional guidance laws,leading to a significant degradation in interception accuracy.To address this issue,this paper proposes an optimal guidance law for intercepting maneuvering targets with equilibrium maneuverability.By introducing a relative reference frame,an optimal equilibrium compensation strategy that accounts for target maneuvering with dynamic delays is proposed.This strategy overcomes the under-compensation or over-compensation limitations of conventional guidance laws,which rely on presupposed target maneuver pattern.Based on this strategy,terminal constraints for equilibrium interception are formulated,and a two-stage optimal integrated guidance and control method is derived using kinematics in the relative reference frame.In the first stage,the guidance law is designed based on a minimum-distance performance index to rapidly eliminate pointing errors and converge to the equilibrium interception constraint.In the second stage,a quadratic optimal performance index of acceleration is adopted to deal with the effects of target maneuver and inner-loop delay with minimum required acceleration,thereby achieving terminal equilibrium interception of highly maneuverable targets.Comparative simulation results demonstrate that the proposed guidance law significantly reduces the required interception acceleration and improves terminal guidance accuracy compared to existing optimal guidance methods.
The high-velocity impact of large-mass kinetic energy block is a key technological means of air defense and anti-missile for effectively detonating the internal charges of missile warhead.To improve the interception capability against tactical ballistic missile,reveal the shock initiation laws of cased charges and determine the shock initiation threshold of high-energy explosive charges,the shock initiation effect of kinetic energy block on cased high-energy explosive charges is studied through numerical simulation.Firstly,a cased charge target with HMX and PBX-9404 as fillers is designed based on the existing literatures and target characteristic analysis,of which the impact surface is made of steels with four typical thicknesses ranging from 10 mm to 40 mm.A numerical simulation model for shock initiation effect is established with by seleting the reasonable material parameters.The response of cased charges under high-velocity impact of tungsten alloy block is simulated,and the shock initiation velocity thresholds at impact angles of 0°-80° are obtained.The variation laws of initiation thresholds under different impact angles and shell thicknesses are analyzed,and a threshold calculation model is constructed.Results show that the shock initiation velocity threshold of HMX presents two stages.It remains between 1175m/s and 1525m/s when the impact angle is less than 50° or the shell thickness is less than 30mm; however,as the impact angle or shell thickness further increases,the threshold rises sharply by nearly 300%.The shock initiation velocity threshold of PBX-9404 ranges from 35m/s to 1475m/s and increases with the increment of impact angle and shell thickness.Notably,the growth rate significantly rises to 200% once the impact angle exceeds 50°,which is approximately linearly correlated to the increase in shell thickness.Furthermore,a predictive model for shock initiation velocity threshold is constructed,achieving R2 correlation coefficients of 0.93 for HMX and 0.90 for PBX-9404.This research provides support for interception-type anti-missile warhead design.
To address the challenge of predicting the drag coefficient of hypersonic fragments undergoing continuous attitude changes in insensitive munition safety testing,a physics-informed neural network (PINN)-based prediction method is proposed.Flight test data inversion reveals that the aerodynamic characteristics of the fragments exhibit unsteady evolution features.Therefore,the prediction of drag coefficient is decoupled into two parts:quasi-steady priori modeling and unsteady effect correction.The flight of fragments under various velocities and attitudes is simulated to construct a prior model mapping from velocity and attitude to the quasi-steady drag coefficient,which,as a known function,is then embedded into the PINN.A joint loss function is formulated with regularization by using the test velocity as the fitting target and Newton’s laws as physical constraints,and a time-varying correction factor is output to modify the quasi-steady drag coefficient.The validation shows that the velocity prediction errors are 0.85% and 0.46% and the drag coefficient errors are 0.078% and 0.049%,respectively,at Mach 5.98 and 6.62,significantly outperforming those of the empirical formulas and the neural networks without physical constraints.Moreover,the prediction process takes only a few seconds,which is far less than the time required for numerical simulation.The proposed method provides support for predicting the hypersonic fragment impact velocities in munition safety assessment.
To address the disturbance rejection problem in the rate stable platform of a seeker,the traditional disturbance observers (DOBs) fail to take into account the time delays such as communication delays and computational delays in the feedback loop.This results in a reduced upper limit of available bandwidth for the observer and a decline in the system's robust stability in response to the model parameter variations,thereby significantly degrading the line-of-sight isolation degree under nonlinear friction disturbances.A disturbance rejection method based on a delay-matching disturbance observer (DM-DOB) is adopted.The DM-DOB greatly increases the usable bandwidth and consequently enhances its disturbance rejection performance by adding a delay equal to that in the feedback loop to the control input channel of the observer.Simulation results show that the DM-DOB reduces the system isolation degree by more than 50%under the same amplitude margin condition.Hardware experiments further validate that,compared with the traditional DOB,the DM-DOB reduces the isolation degree of the stable platform by approximately 50%,significantly improving the line-of-sight stabilization performance of seeker.
For the requirements of precursor charges in tandem warheads,including large-diameter opening,regular through-hole formation,and stable passage of follow-through projectile,this paper investigates the formation characteristics and penetration performance of a W-truncated annular shaped charge (WTASC).A numerical model is validated against existing experimental results,and the roles of the inner liner region,outer liner region and truncated region in the jet formation and target penetration are analyzed.The results show that the damage effect of the WTASC is jointly governed by the high-velocity jet,the annular penetration band and the mass loading from the truncated region.The penetration process can be divided into four stages:initial crater formation by the jet head,main-body penetration,tail loading,and plug-assisted hole enlargement.Structural parameter analysis indicates that the cone angles mainly affect the energy distribution between axial penetration and radial hole expansion,while the truncation length and outer-liner height mainly influence the jet continuity and plugging behavior.Furthermore,a multi-index evaluation system for penetration capability is established by considering entrance-hole,through-hole,exit-hole and plug characteristics.By introducing an equivalent channel damage index and classifying the penetration capability,this study provides an engineering-oriented evaluation method for the structural optimization of WTASC and the precursor-charge opening design of tandem warhead.
