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The navigation problem of the lifting reentry vehicles has attracted much research interest in the past decade.This paper researches the navigation in the blackout zone during the reentry phase of the aircraft,when the communication signals are attenuated and even interrupted by the blackout zone.However,when calculating altitude,a pure classic inertial navigation algorithm appears imprecise and divergent.In order to obtain a more precise aircraft altitude,this paper applies an integrated navigation method based on inertial navigation algorithms,which uses drag derived altitude to aid the inertial navigation during the blackout zone.This method can overcome the shortcomings of the inertial navigation system and improve the navigation accuracy.To further improve the navigation accuracy,the applicable condition and the main error factors,such as the atmospheric coefficient error and drag coefficient error are analyzed in detail.Then the damping circuit design of the navigation control system and the damping coefficients determination is introduced.The feasibility of the method is verified by the typical reentry trajectory simulation,and the influence of the iterative times on the accuracy is analyzed.Simulation results show that iterative three times achieves the best effect. 相似文献
293.
针对空间低照度成像条件下卫星光学图像信息受损严重的问题,提出了一种基于生成对抗网络的空间卫星低照度图像增强方法,提高了图像的平均亮度及对比度,恢复图像细节信息,为图像识别等图像处理技术提供更高质量的数据信息.首先,设计了一种密集连接的生成器,加强了各特征提取阶段中的信息传递以及多层特征的融合,减少了特征信息的损耗,更好... 相似文献
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Chiara Toglia Marco Sabatini Paolo Gasbarri Giovanni B. Palmerini 《Acta Astronautica》2011,68(7-8):1031-1041
Space graspers are complex systems, composed by robotic arms placed on an orbiting platform. In order to fulfil the manoeuvres’ requirements, it is necessary to properly model all the forces acting on the space robot. A fully nonlinear model is used to describe the dynamics, based on a multibody approach. The model includes the orbital motion, the gravity gradient, the aerodynamic effects, as well as the flexibility of the links. The present paper aims to design, thanks to nonlinear optimization algorithms, a class of manoeuvres that, given the same target to be grasped, are characterized by different mission objectives. The grasping mission can be performed with the objective to minimize the power consumption. Collision avoidance constraints can be also added when the target is equipped with solar panels or other appendices. In some cases, large elastic displacements should be expected, possibly leading to an inaccurate positioning of the end-effector. Therefore, different design strategies can require that the manoeuvre is accomplished with minimum vibrations’ amplitude at the end-effector. Performance of the different strategies is analyzed in terms of control effort, trajectory errors, and flexible response of the manipulator. 相似文献
297.
Optimal guidance for reentry vehicles based on indirect Legendre pseudospectral method 总被引:2,自引:0,他引:2
Development of a feasible guidance scheme for reentry vehicles is a challenge because of its significant nonlinearity and multi-constraints. A method for the implementation of three-degree-of-freedom guidance for constrained reentry vehicle is presented in the paper. First, the constrained trajectory is generated by Legendre pseudospectral method (LPM) and then the feasibily of the trajectory is validated. Based on the obtained reference trajectory, the guidance problem is converted into a trajectory state regulation problem which is a linear time varying system. A robust state feedback guidance law is generated in real time using indirect Legendre pseudospectral feedback method. Finally, simulation results illustrate that the overall guidance scheme can lead to a very accurately controlled flight with all the constraints satisfied even in the presence of initial state uncertainty. 相似文献
298.
介绍了一种支持人工决策的满足各种约束的动态调度方法,通过基于仿真的动态调度算法,在约束规则和人工干预综合作用下,实现按照瓶颈设备到非瓶颈设备,关键任务到非关键任务的分层和迭代作业排序,较好地满足了离散车间对生产排产的应用需求. 相似文献
299.
Dynamic characteristics analysis of deployable space structures considering joint clearance 总被引:1,自引:0,他引:1
The clearance in joints influences the dynamic stability and the performance of deployable space structures (DSS). A virtual experimental modal analysis (VEMA) method is proposed to deal with the effects of joint clearance and link flexibility on the dynamic characteristics of the DSS in this paper. The focus is on the finite element modeling of the clearance joint, VEMA and the modal parameters identification of the DSS. The finite element models (FEM) of the clearance joint and the deployable structure are established in ANSYS. The transient dynamic analysis is conducted to provide the time history data of excitation and response for the VEMA. The fast Fourier transform (FFT) technique is used to transform the data from time domain to frequency domain. The frequency response function is calculated to identify the modal parameters of the deployable structure. Experimental verification is provided to indicate the VEMA method is both a cost and time efficient approach to obtain the dynamic characteristics of the DSS. Finally, we analyze the effects of clearance size and gravity on the dynamic characteristics of the DSS. The analysis results indicate that the joint clearance and gravity strongly influence the dynamic characteristics of the DSS. 相似文献
300.
A joint mid-course and terminal course cooperative guidance law for multi-missile salvo attack 总被引:1,自引:0,他引:1
Salvo attacking a surface target by multiple missiles is an effective tactic to enhance the lethality and penetrate the defense system. However, existing cooperative guidance laws in the mid-course or terminal course are not suitable for long- and medium-range missiles or stand-off attacking. Because the initial conditions of cooperative terminal guidance that are generally generated from the mid-course flight may not lead to a successful cooperative terminal guidance without proper mid-course flight adjustment. Meanwhile, cooperative guidance in the mid-course cannot solely guarantee the accuracy of a simultaneous arrival of multiple missiles. Therefore, a joint mid-course and terminal course cooperative guidance law is developed. By building a distinct leader-follower framework, this paper proposes an efficient coordinated Dubins path planning method to synchronize the arrival time of all engaged missiles in the mid-course flight. The planned flight can generate proper initial conditions for cooperative terminal guidance, and also benefit an earliest simultaneous arrival. In the terminal course, an existing cooperative proportional navigation guidance law guides all the engaged missiles to arrive at a target accurately and simultaneously. The integrated guidance law for an intuitive application is summarized. Simulations demonstrate that the proposed method can generate fast and accurate salvo attack. 相似文献