基于数值求解的远程交会路径规划优化研究

研究航天器多脉冲远程交会路径规划问题,由于航天器在变轨过程中,应减少发动机燃料的消耗,有利于增加有效载荷.因此,在多冲量变轨问题描述的基础上,通过选择优化变量建立了无摄动的燃料最优和考虑摄动的燃料最优变轨优化模型,利用遗传算法、序列二次规划及GA+SQP串行混合优化算法进行优化求解,进行了数值仿真.通过仿真实现了不同脉冲次数的远程交会路径规划,并对比分析了摄动的燃料最优变轨优化模型,提出了相应的串行优化策略,通过算例对所提出的算法进行了仿真验证,实现了航天器路径规划数值优化求解的目的,可为多脉冲远程交会提供参考.     

考虑导航误差和摄动影响的椭圆轨道最优交会制导

本文提出了一种新的航天器最优交会制导方法.该方法能够快速精确求解包含J_2项与大气阻力项摄动的椭圆轨道交会问题,并充分考虑非合作目标存在的导航误差,保证交会精度的同时实现所需速度增量最优.首先,本文采用了一种新的状态转移矩阵求解方法,能够对考虑J_2项和大气阻力项摄动的任意偏心率下的相对运动进行描述,得到考虑摄动与偏心率信息的状态约束.其次,建立了导航误差模型,得到描述导航误差的状态约束,并分析其对交会精度与所需速度增量的影响,设计包含加权矩阵的性能指标实现在存在导航误差情况下所需速度增量最优.然后,通过引入松弛变量,将最优交会问题转化为标准二阶锥规划问题进行求解.再者,为了进一步提高相对距离较大的交会任务精度,构建了闭环制导框架.最后,本文通过仿真,验证了设计方法在考虑J_2项与阻力项摄动情况下的有效性,针对椭圆轨道交会问题的精确性以及考虑导航误差情况下所需速度增量的最优性.     

侦察卫星地面机动目标覆盖特性分析与仿真

针对当前军用目标机动过程中易被卫星侦察的问题,对处于不同位置的机动目标进行侦察卫星覆盖特性分析,仿真其覆盖侦察过程.利用卫星工具软件包STK(Satellite Tool Kit)中先进的航天器系统分析软件,建立多摄动条件下侦察卫星星座运动学模型,调用STK的覆盖分析和虚拟现实模块,对卫星地面机动目标的覆盖算法和可视化技术进行研究.覆盖分析仿真结果表明:地面目标在机动过程中,侦察卫星对其实时位置的覆盖数据与目前采用的区域覆盖数据有一定差异,利用仿真结果能够有效减小覆盖预警数据的误差,且仿真结果与实际观测数据拟合良好.所提的方法处理地面机动目标侦察卫星覆盖情况准确度高,侦察卫星作战仿真过程逼真,具有很好的军事应用价值.     

空间飞行器交会策略建模与仿真

空间飞行器由于其所处环境的特殊性,在不同跟随模式下,如何与不同距离目标实现交会,很难在真实环境进行全面的试验和评估;通过对影响空间飞行器交会的各种系统误差和随机误差进行分析,利用变轨算法以及优化算法构建飞行器从初始位置到交会位置的轨道模型,进而得到空间飞行器交会准确度计算模型,利用该模型进行空间飞行器交会仿真,得到一系列仿真数据,对空间飞行器的研究具有参考意义.     

基于lambert理论的多脉冲快速轨道交会研究

对于任意初始相位条件下的圊定轨道间的两航天器交会问题,研究了多脉冲远程快速轨道机动的策略.在燃料消耗一定的情况下,以脉冲次数和时间为变量,通过遗传算法进行全局寻优,可得到一条多脉冲快速机动轨道.仿真结果表明,脉冲次数对燃料消耗和机动时间有极大的影响,在初始条件不利的情况下,利用多脉冲轨道机动,可以较好地解决远程轨道机动的高能耗区.所以,在燃料消耗受限的情况下,根据不同的初始条件,选择脉冲次数,可以达到快速交会的目的,为快速交会提供了可靠依据.     

空间平台发射服务器动力学与双脉冲最优交会

本文研究了空间平台发射服务器的两体耦合动力学,以及服务器与目标星交会对接的双脉冲能耗最省制导问题.平台首先与目标星形成绕飞关系,保持其发射筒轴线瞄准目标星.接到发射指令后,服务器从发射筒中射出．本文采用凯恩方法建立了发射过程平台-服务器两体动力学模型.因为两体耦合影响,平台姿态偏转,服务器出筒时的速度已经不能瞄准目标星.通过小型火箭发动机给其施加初始和末端共两次速度脉冲.初始脉冲发生于服务器出筒瞬间,改变其航向,保证其与目标星准确交会;末端脉冲发生于服务器与目标星交会瞬间,将其相对于目标星的速度减为零,实现软对接.优化指标是能耗最省,即两次速度脉冲幅值的平方和最小,本文将其归结为非线性规划问题.在服务器交会飞行时间远小于平台绕飞目标星周期的情况下,可将平台绕飞平均角速度视作小参数,采用摄动法求出上述非线性规划的一阶近似解,然后以此为迭代初值,快速可靠地找到精确最优解.最后进行了数值仿真验证.     

非合作交会对接的姿态和轨道耦合控制

航天器与非合作目标进行交会对接时,要求控制器能保证二者不发生碰撞.然而,针对航天器非合作交会对接中的避碰问题,还没有成熟的控制策略.本文以服务航天器体坐标系为参考坐标系建立航天器相对姿态轨道耦合运动模型,利用滑模控制设计了一种姿态轨道耦合控制器实现交会对接.通过利用人工势函数理论和基于蔓叶线的虚拟障碍物模型,控制器可以严格地保证服务航天器运行在安全区域内部,避免与目标航天器碰撞.通过李雅普诺夫理论可以证明系统在控制器的作用下是渐近稳定的.数值仿真进一步说明了所提出的控制器的有效性.     

侦察卫星战场应用综合仿真系统

研究卫星战场侦察问题,为提高效率保证变轨的姿态控制,时空关系条件是影响侦察卫星战场应用效能的重要因素,采用仿真技术作为时空关系分析的有效手段.通过建立了侦察卫星战场应用综合仿真系统,包括考虑摄动因素的卫星轨道计算模型,卫星机动变轨模型,战场目标系统模型,卫星战场应用效能评估模型.以某光学侦察卫星的变轨侦察过程为例,进行了卫星变轨过程仿真和战场应用效能评估,仿真结果表明了仿真系统的有效性,为设计提供可靠依据.     

实时数据驱动的交会对接仿真平台设计与实现

航天器地面综合测试时,为了在测试数据显示基础上,动态展示航天器交会对接过程,验证交会对接飞行方案的正确性,为航天员手控交会对接训练提供支持,设计航天器交会对接仿真系统,给出交会对接仿真平台设计架构。通过对航天器建模、虚拟场景装配、模型驱动方法、阳照区/阴影区绘制、姿态和星下点轨迹计算方法研究,开发实现航天器交会对接仿真平台。平台由实时测试数据驱动,在航天器地面静态测试下,可以实时显示航天器三维飞行状态及星下点轨迹。目前,仿真平台已经应用于航天器地面综合测试过程中,同时,平台可以扩展支持航天器在轨飞行动态展示,丰富了航天器测试和监视手段,具有较高工程应用价值。     

舱外转移活动的仿真优化方法研究

航天飞行中宇航员或无人装置的舱外转移活动,要在避免与飞行器碰撞的条件下,尽快以一定姿态到达预定位置.该文依据动力学原理,建立航天器的离散状态方程模型,使用数字仿真的方法,模拟舱外活动体的运动轨迹,按照约束条件,设定允许飞行的初始策略,再用摄动法对此进行优化,得到一个最优策略,达到节省飞行时间与节约燃料的目的.     

基于雷达测距的飞行器交会对接误差补偿控制技术

为解决由视线倾角、视线偏角过大造成的飞行器对接存在误差的问题,实现飞行器交会轨迹的精准对接,提出基于雷达测距的飞行器交会对接误差补偿控制技术。建立空间参考坐标系,根据轨道根数计算结果,推导动力学状态方程,实现对飞行器交会对接过程中的动力学作用分析。按照雷达测距原理,计算飞行器的理论飞行时长及雷达装置作用距离,再联合相关参数指标,确定精度极限的取值范围,实现基于雷达测距的对接误差控制。在三坐标测量机结构模型中,定义飞行位姿拟合条件,再根据位姿误差求解结果,实现对误差参数的补偿修正处理,完成基于雷达测距的飞行器交会对接误差补偿控制方法的设计。对比实验结果表明,应用所提方法可以同时将视线倾角、视线偏角的取值控制在0°-45.0°的数值范围之内,能够较好解决飞行器错误对接的问题,符合精准对接飞行器交会轨迹的实际应用需求。     

交会对接多航天器联合闭环测试模式设计与验证

在载人航天领域,多航天器交会对接技术是研制的关键和难题,闭环测试系统设计的重要性尤为突出,用于交会对接的多航天器联合闭环测试的设计与实施,实现了多航天器间的一体化实时动态同步电测,实现了多航天器及其测试系统的时序同步,以及敏感器及其模拟器和机电系统的动力学模型同步动态联合实时驱动的同步控制,采用了多航天器一体化实时精确控制的自动化测试,以及多航天器间多通道大回路信息流的实时统一管理。解决飞行任务阶段,多航天器交互状态的验证问题,在地面真实呈现交会对接飞行的全过程,达到多船器联合电测的目的。     

Necessary and sufficient conditions of the rendezvous between a single spacecraft and three non-coplanar Walker constellation satellites

The probability of the rendezvous between a single spacecraft and three non-coplanar constellation satellites is studied,and the necessary and sufficient conditions of the rendezvous without orbital maneuver are deduced.The rendezvous orbit design can be transformed into the patching of two spacecraft orbits,either of which can achieve the rendezvous with two satellites.Firstly,due to the precious quality of spherical geometry,the unique existence of the rendezvous orbit for two constellation satellites is ...     

Output feedback stabilization of spacecraft autonomous rendezvous subject to actuator saturation

This paper studies the output feedback dynamic gain scheduled control for stabilizing a spacecraft rendezvous system subject to actuator saturation. By using the parametric Lyapunov equation and the gain scheduling technique, a new observer-based output feedback controller is proposed to solve the semi-global stabilization problem for spacecraft rendezvous system with actuator saturation. By scheduling the design parameter online, the convergence rates of the closed-loop system are improved. Numerical simulations show the effectiveness of the proposed approaches.     

Adaptive Backstepping Control for Spacecraft Rendezvous on Elliptical Orbits Based on Transformed Variables Model

This paper investigates the problem of relative motion control for spacecraft rendezvous on an arbitrary elliptical orbit. The simplified dynamic model describing the relative motion between the chaser spacecraft and the target spacecraft is established via using transformed variables. Due to the presence of time variant parameters in this novel model, robust control scheme and adaptive control scheme are designed to solve the rendezvous problem. Theoretical analyses and simulation results demonstrate the effectiveness of the proposed methods.     

An impulse control approach to spacecraft autonomous rendezvous based on genetic algorithms

This paper proposes a novel approach to spacecraft impulse autonomous rendezvous by using genetic algorithms. Based on the Clohessy-Wiltshire (C-W) equations, the whole rendezvous process is described as a switching system composed of closed-loop system and open-loop system, which correspond to the impulse action phase and free motion phase during the rendezvous process. Based on Lyapunov theory, the autonomous rendezvous problem is regarded as an asymptotic stabilization problem. By introducing two virtual energy functions, the stability of the switching system is analyzed, and the duration of the impulse action and the thrust limitation are considered synthetically. Then, a state-feedback controller design method is proposed, and an approach based on linear matrix inequality and genetic algorithm (GA) is proposed to solve the controller design problem and the calculation steps are presented. With the designed controller, the impulse thrust which satisfies the given thrust constraint is determined according to the real-time relative state between two spacecraft at the impulse instant, and the impulse duration is kept as short as possible. The effectiveness of the proposed approach is illustrated by simulation examples.     

Model predictive control system design and implementation for spacecraft rendezvous

This paper presents the design and implementation of a model predictive control (MPC) system to guide and control a chasing spacecraft during rendezvous with a passive target spacecraft in an elliptical or circular orbit, from the point of target detection all the way to capture. To achieve an efficient system design, the rendezvous manoeuvre has been partitioned into three main phases based on the range of operation, plus a collision-avoidance manoeuvre to be used in event of a fault. Each has its own associated MPC controller. Linear time-varying models are used to enable trajectory predictions in elliptical orbits, whilst a variable prediction horizon is used to achieve finite-time completion of manoeuvres, and a 1-norm cost on velocity change minimises propellant consumption. Constraints are imposed to ensure that trajectories do not collide with the target. A key feature of the design is the implementation of non-convex constraints as switched convex constraints, enabling the use of convex linear and quadratic programming. The system is implemented using commercial-off-the-shelf tools with deployment using automatic code generation in mind, and validated by closed-loop simulation. A significant reduction in total propellant consumption in comparison with a baseline benchmark solution is observed.     

Terminal control of the trajectory and rotational motion of an active spacecraft during a rendezvous with a passive spacecraft

In this work, the problem of a spacecraft’s rendezvous is considered in the radial coordinate system, taking into consideration the effect of the difference gravitational acceleration, using a control algorithm with the prediction model based on the minimization of the generalized work functional. The analytical formulas have been derived to compute the control actions when the motion of the center of mass and the motion about the center of mass, when solving the parametric optimization problem, are considered in a unified terminal formulation. The analytical solution is based on a special prediction model that has an analytical solution in the advanced modeling of the rendezvous process. The results of modeling a spacecraft’s rendezvous are presented.