基于改进定点二乘的重复使用助推飞行器控制分配研究

为适应重复使用助推飞行器(RBV)控制精度和控制可靠性等要求,导致多异类执行机构数量的急剧增加,而各执行机构偏转角、偏转角速率和非连续工作方式的限制影响控制效果。为满足该类飞行器控制系统实时性和控制精度等需求,需要研究计算精度、计算效率更高的控制分配(CA)方法。根据每次迭代所需的浮点运算量,在比较基于二次规划的控制分配算法计算效率的基础上,首先,利用最小代价函数关系将传统定点(FP)二乘优化算法转化为二次规划问题,并给出传统定点二乘优化方法最优解应满足的条件;然后,针对执行机构饱和情况,提出了改进定点(IFP)二乘的控制分配算法以提高计算效率,同时给予详细的推导证明,并基于迭代常数映射的特性,以相邻时刻控制量差的范数达到相关要求给出改进算法的迭代终止条件;最后,基于多种控制分配算法,对所提出的控制分配算法进行了比较仿真,验证该算法的有效性和合理性。     

基于布谷鸟搜索算法的一类变体飞行器容错控制

针对一类存在执行机构故障的分布式结构变体飞行器的控制分配问题,结合整数规划理论,提出一种基于布谷鸟搜索算法的容错控制方法。首先,设计虚拟控制指令,使得系统状态能够很好地跟踪参考模型;然后,将执行器概率性故障与饱和约束转换为整数规划问题中决策变量的约束,从而将执行器控制分配问题转化为一类整数规划问题;最后,采用改进的布谷鸟搜索算法进行求解,得到实际的执行器控制分配指令。仿真结果表明,在执行器存在概率性故障的情况下,该容错控制方法较无容错策略的情况能够有效提升系统的跟踪性能;与遗传算法相比,该算法得到的执行器控制分配结果更加精确。     

考虑负载均衡的过驱动航天器推力器分配方法

以过驱动航天器的推力器控制分配误差最小、推力器负载均衡等为设计目标,构建航天器推力分配混合优化模型,并将其转化为线性规划模型进行求解,提出了一种考虑负载均衡的航天器推力器动态分配算法。该算法在确保分配误差最小前提下,能够降低各推力器的最大分配推力之差,有效均衡各推力器总工作时长和开关次数,进而延长推进系统的整体工作寿命。进一步定义了表征负载均衡性能的推力平衡度和干扰敏感度性能指标,并在此基础上给出了一种分配算法负载均能能力的定量化评价方法。在仿真验证中,采用平衡度和敏感度对算法性能进行定量评估,结果表明该方法在保证控制性能和控制分配误差的前提下,能够有效均衡各推力器最大推力,提高了系统的平衡度和对扰动力矩的鲁棒性。     

基于非线性动态逆的舰载机直接升力航迹控制

针对舰载机人工进场着舰精确轨迹控制中飞行员操纵负担重、着舰环境复杂的问题,提出采用非线性动态逆(NDI)先进控制方法设计基于直接升力的舰载机精确着舰轨迹控制律。首先,综合分析了"魔毯"技术的控制策略,从航迹调整和姿态保持的直接升力解耦控制角度出发,设计了两层NDI回路;然后,采用合理的控制分配方法实现直接升力的舵面分配。仿真结果表明,所提出的精确着舰控制方法能够有效实现"魔毯"式航迹操纵。     

Anti-disturbance attitude control of combined spacecraft with enhanced control allocation scheme

In this paper, we propose a novel anti-disturbance attitude control law for combined spacecraft with an improved closed-loop control allocation scheme. More specifically, a saturated approach is adopted to guarantee the global asymptotic stability under control input saturation. To enhance the robustness of the system, a nonlinear disturbance observer is constructed to compensate the disturbances caused by inertial parameter uncertainty and unmodeled dynamics. Next, the quadratic programming algorithm is used to obtain an optimal open-loop control allocation scheme, where both energy consumption and actuator saturation have been considered in the allocation of the virtual control command. Then, a modified closed-loop control allocation scheme is proposed to reduce the allocation error under the actuator uncertainty. Finally, stability analysis of the closed-loop system with the proposed allocation scheme is provided. Simulation results confirm the effectiveness of the proposed control scheme.     

Effective control allocation using hierarchical multi-objective optimization for multi-phase flight

For different flight phases in an overall flight mission, different control and allocation preferences should be pursued considering lift, drag or maneuverability characteristics. The multi-objective flight control allocation problem for a multi-phase flight mission is studied. For an overall flight mission, different flight phases namely climbing, cruise, maneuver and gliding phases are defined. Firstly, a multi-objective control allocation problem considering drag, lift or control energy preference is constructed. Secondly, considering different control preferences at different flight phases, the analytic hierarchical process method is used to construct a comprehensive performance index from different objectives such as lift or drag preferences. The active set based dynamic programming optimization method is used to solve the real-time optimization problem. For the validation, the Innovative Control Effector (ICE) tailless aircraft nonlinear model and the angular acceleration measurements based adaptive Incremental Backstepping (IBKS) are used to construct the validation platform. Finally, an overall flight mission is simulated to demonstrate the efficiency of the proposed multi-phase and multi-objective flight control allocation method. The results show that the comprehensive performance index for different phases, which are determined from the Analytic Hierarchy Process (AHP) method, can suitably satisfy the preference requirements for different flight phases.     

多操纵面飞机交叉耦合控制分配方法

针对操纵面交叉耦合效应下指令分配不精准的问题,基于序列二次规划提出了一种多操纵面非线性控制分配方法.在舵效线性条件下,引入虚拟控制指令建立了线性控制分配模型;考虑操纵面舵效交叉耦合非线性特征,以最小操纵面偏量为优化目标设计了交叉耦合控制分配器;采用修正BFGS算法改进序列二次规划,有效地求解了交叉耦合控制分配指令.仿真结果表明,所提出的方法能够合理利用所有操纵面并实现精确分配.     

等效带宽在无线ATM网络的MAC协议中的应用

在ＶＢＲ图像的动态时隙分配算法的判决条件中引入了等效带宽的概念。利用等效带宽将终端输出缓冲区内信元个数和终端当前所占用的时隙数之间联系起来，从而得出了动态时隙分配精确的判断条件。结果表明，这种方法提高了图像业务动态时隙分配算法的有效性及无线ＡＴＭ网络的信道利用率。     

Reducing mission operations costs through spacecraft autonomy: the near earth asteroid rendezvous (near) experience

With a maximum time of 12 days out of ground contact and a round-trip light time as high as 56 minutes, The Near Earth Asteroid Rendezvous (NEAR) spacecraft requires a moderate degree of onboard autonomy to react to faults and safe the spacecraft. Beyond the basic safing requirements, additional functions are carried out onboard. For example, on-board calculation of the Sun, Earth, asteroid, and spacecraft positions allow the spacecraft to autonomously orient itself for science and downlink operations. On-board autonomous momentum management during cruise relieves Mission Operations from planning, scheduling, and carrying out many manual momentum dumps. During development, additional operations, such as center-of-mass management during propulsive maneuvers and optical navigation were also considered for onboard autonomy on the NEAR spacecraft, but were not selected. The allocation of functions to onboard software or to ground operations involved tradeoffs such as development time for onboard software versus ground software, resource management, life cycle costs, and spacecraft safety.After two years of cruise operations, considerable experience with the NEAR autonomy system has accrued. The utility of some autonomous capabilities is greater than expected, others less so. Software uploads increased spacecraft autonomy in some cases, and the impact on Mission Operations can be assessed. Allocation of functions between spacecraft autonomy and ground operation during development of future missions can be improved by applying the lessons learned from the NEAR experience.     

航空动力装置任务可靠度模糊预计与分配的综合

根据Vague集的直觉性，定义一种判定Vague值真值的函数，进而给出一种确定Fuzzy隶属度的方法。将此方法应用于模糊综合评判理论，得到一种在设计初期根据专家意见，预计航空动力装置任务可靠度的模糊决策方法。根据预计值和比例组合分配法的思想，先按任务可靠度模型的等效串联模型进行任务可靠度指标的分配，然后再对等效串联模型中冗余部分的指标进行分配。