考虑捷联导引头最小视场角约束的制导策略

针对高超声速飞行器捷联导引头，提出导引头最小视场角（FOV）约束问题。首先分析了导引头视线角变化规律，指出在攻击固定目标时，导引头最小视场角约束在弹道末段无法被满足，导引头将丢失目标。在此基础上，基于缩短导引头丢失目标距离的目标，提出一种满足导引头最小视场角约束的制导策略。该策略不依赖于末制导律形式，当最小视场角约束无法被满足时，改变原有制导指令，主动改变弹道轨迹以增加弹体视线角，避免超出视场范围。其次，针对飞行器过载约束，设计了制导策略切换点，在到达切换点时该制导策略将结束工作，避免末端过载过大超出约束。通过对比仿真验证了所提出制导策略有效性，能够大幅度减少导引头丢失目标距离，工程上有利于提高末端命中精度。     

PMSM电流预测控制参数误差量化分析方法

交流永磁同步电机（PMSM）电流环控制性能是制约交流伺服系统性能的关键。电流预测控制拥有更快的动态响应、更低的电流谐波和优良的转矩响应，但该算法依赖精确的电机模型，参数失配会引发稳态电流误差，无法输出额定转矩，进而导致电机转矩输出效率降低。根据永磁同步电机电流预测模型，详细分析了d、q轴电流静差产生的原因，以及电流预测控制对电机参数误差的敏感性，提出了一种参数误差量化分析方法。该方法引入了电机参数偏差因子，量化描述了电机电感、磁链参数误差与电流静差之间的制约关系。通过仿真分析，验证了所提方法的合理性，为高性能永磁伺服电流预测数字控制技术打下了良好基础。     

Propulsionless planar phasing of multiple satellites using deep reinforcement learning

This work creates a framework for solving highly non-linear satellite formation control problems by using model-free policy optimisation deep reinforcement learning (DRL) methods. This work considers, believed to be for the first time, DRL methods, such as advantage actor-critic method (A2C) and proximal policy optimisation (PPO), to solve the example satellite formation problem of propellantless planar phasing of multiple satellites. Three degree-of-freedom simulations, including a novel surrogate propagation model, are used to train the deep reinforcement learning agents. During training, the agents actuated their motion through cross-sectional area changes which altered the environmental accelerations acting on them. The DRL framework designed in this work successfully coordinated three spacecraft to achieve a propellantless planar phasing manoeuvre. This work has created a DRL framework that can be used to solve complex satellite formation flying problems, such as planar phasing of multiple satellites and in doing so provides key insights into achieving optimal and robust formation control using reinforcement learning.     

全模颤振风洞试验三索悬挂系统多体动力学分析

全模颤振风洞试验需要通过软支撑系统模拟飞行器的自由飞行状态并调整模型姿态达到配平状态。参考NASA双索悬挂方案，提出了一种两电机驱动的三索悬挂系统，利用后方两索的同向/反向联动实现模型俯仰和滚转姿态的调整，利用弹簧刚度以及钢绳张力设计实现支撑频率要求。基于柔性多体动力学方法，建立了包括飞行器刚体模型、柔性索、滑轮、弹簧、气动力模型、伺服电机控制在内的复杂系统动力学模型，其中，利用任意拉格朗日-欧拉（ALE）变长度索单元描述钢绳，利用不约束物质坐标的索结点约束描述钢绳与滑轮相互作用，利用索结点物质输运速度约束描述伺服电机绞盘，利用飞行力学的气动力模型描述吹风下的气动力。基于该模型，通过小扰动响应辨识研究了弹簧刚度、钢绳张力、连接点位置等因素对支撑频率的影响规律，并分析了系统姿态调整能力，俯仰调整范围达到-12.5°~12.5°，滚转调整范围达到-45°~45°。采用滑轮处电位计测量的钢绳相对位移作为反馈信号，基于设计的控制律利用多体动力学求解器与Simulink对风洞吹风下的姿态调整过程进行仿真，模型达到配平状态，获得了吹风下的索拉力和伺服电机功率，为系统设计提供基础。     

Neural adaptive control for a ground experiment of the space proximity operation in a six-degree-of-freedom micro-gravity simulation system

In this study, a neural adaptive controller is developed for a ground experiment with a spacecraft proximity operation. As the water resistance in the experiment is highly nonlinear and can significantly affect the fidelity of the ground experiment, the water resistance must be estimated accurately and compensated using an active force online. For this problem, a novel control algorithm combined with Chebyshev Neural Networks (CNN) and an Active Disturbance Rejection Control (ADRC) is proposed. Specifically, the CNN algorithm is used to estimate the water resistance. The advantage of the CNN estimation is that the coefficients of the approximation can be adaptively changed to minimize the estimation error. Combined with the ADRC algorithm, the total disturbance is compensated in the experiment to improve the fidelity. The dynamic model of the spacecraft proximity maneuver in the experiment is established. The ground experiment of the proximity maneuver that considers an obstacle is provided to verify the efficiency of the proposed controller. The results demonstrate that the proposed method outperforms the pure ADRC method and can achieve close-to-real-time performance for the spacecraft proximity maneuver.     

基于避障伪距离的自由漂浮空间机器人规划跟踪一体化控制

针对自由漂浮空间机器人(Free Floating Space Robot,FFSR)的避障规划与控制问题，提出一种FFSR的避障规划-跟踪一体化控制方法。首先，基于障碍物伪距离技术，采用FFSR逆几何模型求解期望末端位姿下的连杆伪距离估计值，进而通过求解非线性优化问题，获得FFSR避障期望轨迹。其次，将全局轨迹规划与局部在线避障相结合，辅以离散状态黎卡提方程（DSDRE）控制方法实现FFSR的避障规划-跟踪一体化控制。最后，采用6R空间机器人模型验证了所提方法的有效性。仿真结果表明，该方法能够实现FFSR的避障控制，有效克服了传统FFSR控制中末端轨迹规划与控制相分离的问题，提高了FFSR的环境适应性。     

火星车低气压无风热环境模拟试验技术

为模拟火星车工作时所处大温差、低气压环境,文章以自主研制的调温热沉系统和压力控制系统为依托,实现试验容器热沉系统温度在-135~27℃间任意快速调节,均匀性优于±5℃;试验容器内气体压力控制值与目标压力值之差在±10 Pa之内。在国内首次完成无风环境下的火星车温控模拟舱验证试验,为火星车热分析模型修正以及后续火星车有风热环境试验提供了参考。     

飞机动态推出控制策略仿真优化模型

机场离港运行的无序化造成滑行过程中的长时间排队等待及大量燃油浪费。为了减少燃油消耗和废气排放,在已有的动态推出控制策略基础上提出了阶梯函数控制策略(Step function,SPC)和非线性函数动态推出策略(Nonlinear function,NPC)的一般形式,以离港成本为目标,建立了基于停机位等待惩罚的动态推出控制模型,在不延误的前提下提出了一种基于网格参数优化的蒙特卡洛仿真优化算法。通过北京首都机场实际运行数据对推出过程进行仿真计算,并与无控制策略以及传统N-control策略的最优可达解进行仿真对比,结果表明:在不延误的前提下,提出的推出策略可以更加有效地降低平均滑行道滑行时间,NPC策略的离港运行成本和燃油成本可降低45.52%和54.23%,SPC虽然成本节省劣于NPC策略,但是其简单的操作方式可以为离港推出调度方式的改进提供决策支持。     

基于动态补偿的多电机控制算法

多电机协调控制达到转速一致是电机控制中的一个关键难题，外加负载变动和电机参数变化时会引起电机性能的下降，达不到良好的控制效果。为使电机间保持转速同步，建立了永磁同步电机d-q坐标系下的矢量控制数学模型，基于转速跟随控制，提出一种基于单神经元PID的变增益速度补偿器进行偏差耦合控制。在MATLAB/Simulink建立了3台永磁同步电机的仿真模型。仿真结果表明，与传统PID固定增益速度补偿器算法相比，单神经元PID的变增益速度补偿器具有更强的鲁棒性以及更快的收敛性。     

A novel architecture of electro-hydrostatic actuator with digital distribution

To address the flow imbalance rapidly of the asymmetric Electro-Hydrostatic Actuator (EHA), this paper presents a novel architecture of asymmetric EHA with the Digital Distribution (EHA-DD). It also improves the flow nonlinearity and control accuracy of the pump, especially in the low-speed condition. The digital distribution with two High-Speed on–off Valves (HSVs) not only balances flow instead of the check valves, but also replaces the pump at the low-speed to control output flow by adjusting the PWM signal. The pump and HSVs are the crucial components to control flow output. Firstly, the flow calculation models of the pump and the duty ratio inversed model of the HSV are obtained through experimental tests and the identification method. To get the control input signal for the required flow, the pump speed and PWM duty ratio for the HSVs are inversed to compensate for flow output. Further, a multimode digital flow distribution control method based on pump speed, mainly including the pump-controlled mode for large flow demand and valve-controlled mode for little flow demand, is proposed to control the accurate flow output actively. The step extension experiments based on the flow calculation models are conducted on the EHA-DD prototype under elastic, opposite varying load. The results demonstrate that the EHA-DD realizes little position error by accurate flow control, and it is also beneficial to improve the service life of the pump.