Multiconstraint adaptive three-dimensional guidance law using convex optimization

The traditional guidance law only guarantees the accuracy of attacking a target. However, the look angle and acceleration constraints are indispensable in applications. A new adaptive three-dimensional proportional navigation(PN) guidance law is proposed based on convex optimization. Decomposition of the three-dimensional space is carried out to establish threedimensional kinematic engagements. The constraints and the performance index are disposed by using the convex optimization method. PN guidance gains can be obtained by solving the optimization problem. This solution is more rapid and programmatic than the traditional method and provides a foundation for future online guidance methods, which is of great value for engineering applications.

Matrix Riccati Equations in Optimal Control

In this paper, the matrix Riccati equation is considered. There is no general way for solving the matrix Riccati equation despite the many fields to which it applies. While scalar Riccati equation has been studied thoroughly, matrix Riccati equation of which scalar Riccati equations is a particular case, is much less investigated. This article proposes a change of variable that allows to find explicit solution of the Matrix Riccati equation. We then apply this solution to Optimal Control.

An Improved Rate Control Method Based on Modification at Scene Change for H.264

This paper presents an improved rate control method for H.264. First, the scene changes are detected by the average absolute difference of the brightness histograms between the adjacent frames. Then, the bit allocation and quantization parameters are adjusted, using a certain threshold. In addition, the calculation of the mean absolute difference （MAD） is modified in an alternative way, which makes the rate distortion optimization （RDO） more accurate. Extensive simulation results show that the proposed method, compared with G012, can improve the average peak signal-to-noise ratio （PSNR） and moderate the image quality.

Design of Guided Air Ammunition's Optimal Guidance Law

Some long distance air ammunition can be used to attack large still target. According to this character and according to the mathematical description of target-missile relative motion built by the message supplied by the strapdown inertial navigation system/global position system （SINS/GPS） of air ammunition, optimal guidance law is designed by applying optimal control theory. The simulation is provided to indicate that when the air ammunition reaches the target, its line-of-sight （LOS） and LOS angular rate can nearly equal zero. So the air ammunition can get good terminal attitude, and the air ammunition reaches the target at the expected velocity and heading.

The Optimal Control for the Output Feedback Stochastic System at the Risk-Sensitive Cost

The optimal control of the partially observable stochastic system at the risk-sensitive cost is considered in this paper. The system dynamics has a general correlation between system and measurement noise. And the risk-sensitive cost contains a general quadratic term (with cross terms and extra linear terms). The explicit solution of such a problem is presented here using the output feedback control method. This clean and direct derivation enables one to convert such partial observable problems into the equivalent complete observable control problems and use the routine ways to solve them.

Aircraft Optimal Separation Allocation Based on Global Optimization Algorithm

A dynamic programming-sequential quadratic programming(DP-SQP)combined algorithm is proposed to address the problem that the traditional continuous control method has high computational complexity and is easy to fall into local optimal solution.To solve the globally optimal control law sequence,we use the dynamic programming algorithm to discretize the separation control decision-making process into a series of sub-stages based on the time characteristics of the separation allocation model,and recursion from the end stage to the initial stage.The sequential quadratic programming algorithm is then used to solve the optimal return function and the optimal control law for each sub-stage.Comparative simulations of the combined algorithm and the traditional algorithm are designed to validate the superiority of the combined algorithm.Aircraft-following and cross-conflict simulation examples are created to demonstrate the combined algorithm’s adaptability to various conflict scenarios.The simulation results demonstrate the separation deploy strategy’s effectiveness,efficiency,and adaptability.

Motoyosi Sugita—A “Widely Unknown” Japanese Thermodynamicist Who Explored the 4th Law of Thermodynamics for Creation of the Theory of Life

The purpose of this paper is to introduce to you, the Western people, nowadays a “widely unknown” Japanese thermodynamicist by the name of Motoyosi Sugita and his study on the thermodynamics of transient phenomena and his theory of life. This is because although he was one of the top theoretical physicists in Japan before, during and after WWII and after WWII he promoted the establishment of the biophysical society of Japan as one of the founding members, he himself and his studies themselves have seemed to be totally forgotten nowadays in spite that his study was absolutely important for the study of life. Therefore, in this paper I would like to present what kind of person he was and what he studied in physics as a review on the physics work of Motoyosi Sugita for the first time. I will follow his past studies to introduce his ideas in theoretical physics as well as in biophysics as follows: He proposed the bright ideas such as the quasi-static change in the broad sense, the virtual heat, and the field of chemical potential etc. in order to establish his own theory of thermodynamics of transient phenomena, as the generalization of the Onsager-Prigogine’s theory of the irreversible processes. By the concept of the field of chemical potential that acquired the nonlinear transport, he was seemingly successful to exceed and go beyond the scope of Onsager and Prigogine. Once he established his thermodynamics, he explored the existence of the 4th law of thermodynamics for the foundation of theory of life. He applied it to broad categories of transient phenomena including life and life being such as the theory of metabolism. He regarded the 4th law of thermodynamics as the maximum principle in transient phenomena. He tried to prove it all life long. Since I have recently found that his maximum principle can be included in more general maximum principle, which was known as the Pontryagin’s maximum principle in the theory of optimal control, I would like to explain such theories produced by Motoyosi Sugita as detailed as possible. And also I have put short history of Motoyosi Sugita’s personal life in order for you to know him well. I hope that this article helps you to know this wonderful man and understand what he did in the past, which was totally forgotten in the world and even in Japan.

Design of Near-optimal Earth Escape Orbits for Solar Sail Spacecraft

With the increase of the interest in solar sailing, it is required to provide a basis for future detailed planetary escape mission analysis by drawing together prior work, clarifying and explaining previously anomalies. In this paper, a technique for escaping the Earth by using a solar sail is developed and numerically simulated. The spacecraft is initially in a geosynchronous transfer orbit (GTO). Blended solar sail analytical control law, explicitly independent of time, are then presented, which provide near-optimal escape trajectories and maintain a safe minimum altitude and which are suitable as a potential autonomous onboard controller. This control law is investigated from a range of initial conditions and is shown to maintain the optimality previously demonstrated by the use of a single-energy gain control law but without the risk of planetary collision. Finally, it is shown that the blending solar sail analytical control law is suitable for solar sail on-board autonomously control system.

汽车横向摆动前馈调节LQR控制设计及仿真分析

对自动驾驶的横向位置参数与速度进行有效控制,需要通过设置智能控制技术来实现。为了提高汽车无人驾驶时横向摆动控制精度,设计了一种能够自主调节的前馈调节线性最优控制LQR控制器。利用非预瞄控制模式建立了对路径误差跟踪模型,建立了包含了路径跟踪偏差和车-路参数的自适应矩阵,并开展仿真测试分析。双移线测试表明,采用前馈LQR优化控制器进行处理时得到的距离偏差不超过0.3m,获得了0.1rad以内的航向偏差。LQR控制器中加入前馈控制程序后应对控制参数进行适当调节便可以达到目的。连续换道测试表明,在LQR控制器中加入前馈控制后达到更小偏差,路径跟踪精度获得了明显提升,表现出更优控制效果。该研究对提高无人驾驶汽车运行稳定性具有很好的理论支撑价值,易于推广应用。

宽体飞机地面主轮协同转弯控制律设计

主轮协同转弯技术能有效提高飞机的地面机动性,降低主起落架在转弯过程中受到的附加侧向扭矩,减小重载飞机地面转弯半径,但目前实现此技术的前主轮转角控制律设计方法尚不明确。提出以主起落架受力为约束条件,计算不同滑行速度下的前主轮转角关系,在全速度范围内进行分段选择并离散化,据此设计前主轮协同转弯控制律,以原理样机为对象进行仿真分析,验证了该控制律能有效降低两侧主起落架扭矩和的峰值。提出的设计方法对多轮系地面运载装备的复合转弯控制律设计具有一定的理论指导意义。

基于灰狼算法的步进电机滑模控制系统设计

为了改善转台方位轴的位置精准度及抖振现象,本文围绕步进电机控制系统展开研究。设计了指数趋近律的位置方程,应用了灰狼优化算法整定滑模控制系统的多项参数。在此基础上建立了数学模型,使用MATLAB/Simulink构建了位置三闭环仿真,对系统的位置精准度、抗干扰能力进行分析,并与PID控制系统、传统的滑模控制系统进行了比较。仿真结果表明优化后的控制系统较稳定,响应速度快,抗干扰能力强。最后基于STM32F10ZET6主控芯片搭建了硬件平台,实验证明了优化后的控制策略有效提升了位置精准度,保证了系统的可靠性。

拓扑优化相变热沉在不同重力场的性能

为强化相变热沉的性能,基于带惩罚的固体各向同性材料(SIMP)法对山梨糖醇相变热沉进行传热拓扑优化设计。对拓扑优化的相变热沉(Ⅰ)和直肋式的相变热沉(Ⅱ)进行定常重力(0~20g)和周期性重力条件的数值模拟研究。利用无量纲数对比二者的热性能,研究结果表明:热沉Ⅰ的吸热和均热性能优于热沉Ⅱ;在相同重力环境下,以80℃为目标,热沉Ⅰ温控时间比热沉Ⅱ平均多26.8%;微低重力下热沉内部近乎导热,略逊于常规重力下热性能;超重力强化的自然对流可以显著提升热沉性能,10g条件相比常规重力的温控时间增加8.94%,而相同Ra^(*)下,周期性重力对热沉Ⅰ的性能有抑制作用。研究结果对飞行器载相变热沉的地面细化设计有一定指导意义。

超重条件下相变热沉结构拓扑优化及温控性能研究

利用相变热沉有望解决高速飞行器大热耗电子设备的热控难题。为强化相变热沉温控性能,基于固体各向同性罚函数的变密度拓扑优化方法对相变热沉进行传热拓扑优化设计。而飞行器在机动飞行过程中常处于超重状态,其可能会影响相变热沉的性能。因此,对拓扑优化的导热式优化热沉(Ⅰ)和自然对流式优化热沉(Ⅱ)在超重(1g~7g)下的温控性能进行了数值研究。研究结果表明:热沉Ⅱ吸热速度和温控性能优于热沉Ⅰ,PCM总融化时长缩短11 s;以60℃为目标,在1g、3g、5g、和7g下,热沉Ⅱ的温控时长比热沉Ⅰ分别延长了19.75%、17.44%、4.01%和1.62%;超重会强化PCM间的自然对流,显著提升热沉温控性能,但其强化效应随超重的增强而减弱;超重对热沉Ⅰ的强化作用大于热沉Ⅱ,且会缩短热沉间性能差异。

基于粒子群优化的组合导引律模型

针对导弹打击机动目标的问题,提出了一种基于组合导引律的粒子群优化算法以应对战场环境中的机动目标打击问题。首先对三维弹目运动关系进行分析,设计了一种包含角度和时间偏置项的比例导引律,旨在有效抑制终端角度变化,同时确保打击时间的精确控制。为实现最优导引律参数的求解,研究构建了以打击角、打击时间、法向加速度和脱靶量等约束条件为基础的代价函数。采用标准粒子群算法进行自适应寻优,通过迭代计算确定使代价函数最小化的最优导引律参数,进而得到满足约束条件的最优弹道。为验证算法的有效性,设置了机动目标场景,并设计了与原始比例导引律的对比仿真实验以及多种打击时间测试实验。实验结果表明,相较于传统比例导引律,基于粒子群优化的组合导引律算法在应对机动目标时能够生成满足打击时间要求及其他约束条件的弹道,并在不同打击时间设定下均展现出良好的打击效果,具有广阔的应用前景。

高轨卫星角动量管理的太阳电池阵转角控制

为了延长高轨卫星的角动量卸载周期,提出一种用于高轨卫星角动量管理的太阳电池阵转角控制方法。首先,构建出太阳电池阵转角控制作用模型,并将用于卫星角动量管理的太阳电池阵转角控制转化为约束优化问题。然后,从工程实用的角度出发,根据常用的两翼太阳电池阵对称布局的特点,简化用于角动量管理的太阳电池阵转角控制问题,提出简单实用的太阳电池阵转角控制律。最后,通过数值仿真和某遥感卫星的在轨环境干扰数据对所提方法进行验证。结果表明,所提方法可以显著降低卫星角动量的积累,延长角动量卸载周期。

The stochastic sliding mode variable structure guidance laws based on optimal control theory

A stochastic sliding-mode variable structure guidance law involving optimal control theory is presented for the missile target intercept model, in which state noise, uncertain system parameters, target movement and measured noise are considered. This guidance law synthesizes the merits of optimal guidance law with line-of-sight rate convergence and sliding-mode guidance law with strong robustness. Through theoretic analysis, it is proved that the sliding mode hyperplane is sub-achievable in the closed loop system. The numerical results show the effectiveness of the proposed control algorithm.

有限相依随机序列的非贝叶斯变点最优监测

本文研究了有限相依样本序列的非贝叶斯变点检测问题.通过引入非负动态随机控制线,我们不仅构造并证明了两个最优控制图,而且还得到了比原定义更容易计算的Lorden测度和Pollak测度的最小值的表达式.

基于DFIG无功优化控制的直流换相失败暂态过电压抑制

当高压直流系统发生换相失败时,送端电网电压呈现“先低后高”连续变化的特征,风电机组动态控制不佳,严重时会造成脱网。为克服传统国标控制策略未考虑电压连续变化特征下的控制“空白区”问题,揭示了换相失败暂态过电压的形成机理并分析了其暂态形态特性;在传统国标控制策略的基础上,引入无功电流系数细化电流指令并利用转子侧换流器进行优先分配,确定了基于双馈感应发电机(DFIG)无功优化的故障穿越控制策略。基于MATLAB/Simulink仿真平台对所提控制策略进行验证。结果表明相较于传统国标控制策略,所提控制策略能够进一步抑制换相失败恢复阶段的暂态过电压现象。

基于自抗扰控制的共轴直升机姿态控制律设计

以某型共轴双旋翼无人直升机作为研究对象,对无人机返航进场与降落着舰阶段的抗扰动问题进行研究。针对海上着舰环境下的外界干扰与不确定性问题,选用自抗扰控制器设计共轴直升机姿态控制律,以提高共轴直升机对外部扰动的抗扰性能。针对自抗扰控制律调整参数过多问题,设计改进粒子群算法进行自动参数优化。仿真结果表明:改进粒子群算法能够显著提高参数整定速度,且精度更高;优化参数后的自抗扰控制律在强干扰环境下具备良好的动态响应与鲁棒性。

高速柔性容差机构抑振研究及其最优驱动设计

智能建造中需要引入钢筋自动捆扎设备,以提高捆扎效率及质量,降低工人劳动强度,为人机协作提供新的应用场景。针对现阶段钢筋自动捆扎设备视觉定位精度不高的技术瓶颈问题,引入容差机构,利用容差机构欠驱动的特性弥补视觉定位误差。但欠驱动中的弹性构件在运动平台高速运行时会因惯性力导致系统振动,影响捆扎精度并限制工作效率。针对这一问题,运用最优化动态控制理论,确定了控制运动规律和关键的系统结构设计参数,旨在减少非稳定过渡时间、能量消耗和稳态误差。对研究结果进行了数字仿真与实验验证,结果显示:与传统驱动方法相比,经最优控制设计的驱动方式在非稳定过渡时间和稳态误差方面具有明显的综合优势。