考虑气动效应不确定性的气动辅助变轨制导算法

气动辅助变轨技术在节省推进、延长航天器寿命等方面具有可观的应用价值,但工程实践却严重受制于气动效应不确定性,因此,设计了针对气动效应不确定性的SMC-$H_2/H_\infty$鲁棒制导算法.算法基于高斯伪谱法获取的标称轨迹和控制序列,通过构建气动效应的不确定性模型,利用奇异摄动理论将气动辅助变轨飞行器动力学划分为位置和速度回路,设计滑模和鲁棒$H_2/H_\infty$控制器分别实现制导控制.进一步,通过MatLab/xPC和飞行器机载计算模块组成的实时仿真系统验证,所设计鲁棒制导算法在计算复杂度满足工程约束前提下,能够在存在气动效应不确定性的场景下实现标称轨迹的跟踪,表明所设计的鲁棒制导算法能够有效地增强系统的鲁棒性,具有重要的工程应用价值.     

An optimal discrete control strategy for interplanetary guidance

The problem of guiding one state of a linear dynamical system to a prescribed rms terminal accuracy in the presence of injection, measurement, as well as engine-mechanization errors with a minimum average effort, is considered. Orbit corrections are assumed to be mechanized in the form of discrete velocity increments whose areas are proportional to the predicted miss distance. Equations are derived for computing the feedback gains as a function of the correction times. It is then shown how the spacings between successive corrections can be optimized. This is done by outlining a computation procedure based on the theory of dynamic programming. The optimum solution includes the effect of the loss of information caused by the mechanization error. The results are applied to a simple but illustrative example that approximates the terminal phase of an interplanetary trip. A numerical study is made relating the number of corrections and the required amount of propellant for various terminal accuracies and mechanization errors with typical initial errors. The computer results make evident the improvement of the multiple correction strategy over the design of using only one correction, and seem to indicate that the improvement obtained using more than three to four corrections is negligible. Moreover, it shows that there is an optimum number of corrections for a given size of mechanization error.     

An optimal guidance approximation theory

Synthesis of optimal guidance approximations is undertaken by means of a perturbation theory approach and a scheme for obtaining linear, quadratic and higher order feedback approximations to the optimal control presented. Mechanization is carried out in terms of state deviations from an optimal reference trajectory with the comparison point along the reference selected so that the state comparison is approximately transverse. A simple example is treated analytically, linear and quadratic feedback expressions obtained, and some digital computer simulation results presented which permit a comparison of system performance and accuracy between various approximations.     

Precision program guidance of an nonrigid orbital telescope

New capabilities of direct numerical technology for calculation of open-loop controls for nonlinear objects are considered. The modification of direct algorithm closed with respect to the output of the complete model predicting the state of a nonrigid controlled object is presented. According to this algorithm the control law is iteratively calculated using a reduced system with the order considerably lower than the complete model. The new algorithm provides calculation of high accuracy and low-sensitive to inaccuracy of initial data (Tikhonov stable, or robust) open-loop control for dynamic models with high dimensionality. The operation of the modified algorithm is demonstrated for the calculation of the open-loop control for the regime of reorientation of an orbital telescope whose dynamic model takes into account the flexibility of its structural elements as an example. The objective of the numerical experiment is the analysis of the influence on dynamics of the programmed controlled process of essential perturbations of the model: changes in its structure (due to the account offlexibility of solar panels), parameters (spread of moments of partial tones of solar panels, coefficients of inertial coupling of partial tones of solar panels and the telescope frame, and eigenfrequencies of solar panels) was considered. Results of calculations testify that the theoretically established property of stability of direct algorithm to errors of initial data (well conditioned algorithm) provides robustness and, at the same time, a high accuracy open-loop control according to laws calculated using the direct method.     

Three-dimensional optimal path planning for waypoint guidance of an autonomous underwater vehicle

In this paper, optimal three-dimensional paths are generated offline for waypoint guidance of a miniature Autonomous Underwater Vehicle (AUV). Having the starting point, the destination point, and the position and dimension of the obstacles, the AUV is intended to systematically plan an optimal path toward the target. The path is defined as a set of waypoints to be passed by the vehicle. Four criteria are considered for evaluation of an optimal path; they are “total length of path”, “margin of safety”, “smoothness of the planar motion” and “gradient of diving”. A set of Pareto-optimal solutions is found where each solution represents an optimal feasible path that cannot be outrun by any other path considering all four criteria. Then, a proposed three-dimensional guidance system is used for guidance of the AUV through selected optimal paths. This system is inspired from the Line-of-Sight (LOS) guidance strategy; the idea is to select the desired depth, presumed proportional to the horizontal distance of the AUV and the target. To develop this guidance strategy, the dynamic modeling of this novel miniature AUV is also derived. The simulation results show that this guidance system efficiently guides the AUV through the optimal paths.     

考虑导弹速度时变的角度约束最优中制导律

以导弹逆轨拦截高速运动目标为背景,本文运用间接高斯伪谱法设计带攻击角度约束的最优中制导律.通过零化弹目相对法向速度,将攻击角度约束转化为视线角约束.考虑导弹速度时变的情况,建立带角度约束的制导方程.根据极小值原理推导最优中制导律的解析表达式,运用高斯伪谱法对最优中制导律进行离散化,把微分方程转化为代数方程,避免了求解Riccati方程.该方法不需要预先知道导弹未来的速度信息,计算量小,具有较好的实时性.仿真结果表明该中制导律可以满足逆轨拦截对弹目交会角的约束,且中制导末端的过载较小.     

On the optimal pure strategy sets for a mixed missile guidance lawsynthesis

The terminal phase of a missile-versus-aircraft engagement in a noise-corrupted environment is formulated as an imperfect information zero-sum differential game. The payoff of the game is the single shot kill probability of the missile to be maximized by its designer and minimized by the pilot of the evading aircraft. In the past, it was shown that in such a game the optimal strategy of the evader is mixed. The proposed formulation allows a mixed strategy for the pursuer. The mathematical basis for such an analysis is provided, and a constructive methodology for the synthesis of missile guidance laws based on the concept of mixed strategies is outlined     

Multi-constrained intelligent gliding guidance via optimal control and DQN

In order to improve the adaptability and robustness of gliding guidance under complex environments and multiple constraints, this study proposes an intelligent gliding guidance strategy based on the optimal guidance, predictor-corrector technique, and deep reinforcement learning(DRL). Longitudinal optimal guidance was introduced to satisfy the altitude and velocity inclination constraints, and lateral maneuvering was used to control the terminal velocity magnitude and position. The maneuvering a...     

基于自适应最优控制的有限时间微分对策制导律

针对固定末端时刻拦截机动目标的制导系统,本文首先构建了非线性有限时间微分对策框架,将导弹拦截非线性系统的最优问题转化为一般非线性系统的最优控制问题,并通过自适应动态规划算法(adaptive dynamic programming, ADP)获得近似最优值函数与最优控制策略.为了有效实现该算法,本文利用一个具有时变权值和激活函数的评价网络来逼近Hamilton-Jacobi-Isaacs(HJI)方程的解,并在线更新.通过李雅普诺夫法来证明本文提出的控制策略可保证闭环微分对策系统稳定性和评价网络权值近似误差的有界性.最后给出一个非线性导弹拦截目标系统的仿真例子验证了该方法的可行性和有效性.     

垃圾中转站最优选址及垃圾最优转运方案研究

针对城市垃圾中转站选址问题,建立了中转站最优选址数学模型。给出了一种中心转移算法,其不但解决了中转站的最优选址问题,而且给出了最优选址方案下,每个居民点垃圾的最优转运方案。由于解决这一优化问题的中心转移算法是一种单调迭代算法,因此其不但使用方便,而且有很好的运算效率。     

Learning to transfer optimal navigation policies

Autonomous agents that act in the real world utilizing sensory input greatly rely on the ability to plan their actions and to transfer these skills across tasks. The majority of path-planning approaches for mobile robots, however, solve the current navigation problem from scratch, given the current and goal configuration of the robot. Consequently, these approaches yield highly efficient plans for the specific situation, but the computed policies typically do not transfer to other, similar tasks. In this paper, we propose to apply techniques from statistical relational learning to the path-planning problem. More precisely, we propose to learn relational decision trees as abstract navigation strategies from example paths. Relational abstraction has several interesting and important properties. First, it allows a mobile robot to imitate navigation behavior shown by users or by optimal policies. Second, it yields comprehensible models of behavior. Finally, a navigation policy learned in one environment naturally transfers to unknown environments. In several experiments with real robots and in simulated runs, we demonstrate that our approach yields efficient navigation plans. We show that our system is robust against observation noise and can outperform hand-crafted policies.     

基于纳什均衡迁移学习的碳-能复合流自律优化

提出了一种全新的纳什均衡迁移学习算法,并应用于求解大规模电力系统分散式碳–能复合流自律优化.首次引入碳排放责任分摊机制,避免了碳排放责任的重复计算.将大规模电网分解成若干小型区域电网,每个小型区域电网被定义为一个智能体,通过纳什博弈实现分散式自律优化.智能体利用记忆矩阵对寻优知识进行存储,并通过多个个体与环境的反复交互实现记忆更新;采用状态–动作链对记忆矩阵进行降维,有效避免了"维数灾难".此外,基于相似度的迁移学习可以对历史任务知识进行高效提炼,提高了新任务寻优效率.IEEE 57和300节点系统仿真表明:所提算法非常适合求解大规模电网的碳–能复合流自律优化,在保证纳什均衡解质量的同时,明显加快寻优速度.     

Optimal guidance law for cooperative attack of multiple missiles based on optimal control theory

This article considers the problem of optimal guidance laws for cooperative attack of multiple missiles based on the optimal control theory. New guidance laws are presented such that multiple missiles attack a single target simultaneously. Simulation results show the effectiveness of the proposed algorithms.     

Neighbouring extremals for nonlinear systems with control constraints

In this paper, we consider a class of nonlinear optimal control problems subject to control constraints. We assume that an initial condition for the dynamical system is specified. Then, we can easily compute an openloop optimal control using any convenient optimal control software package. Now, suppose the optimal trajectory is perturbed due to a change in initial conditions or uncertainty in the model equations. If the perturbations are not too large, it is known that the neighbouring extremal approach can be used to obtain a feedback law which adjusts the open-loop optimal control accordingly provided there are no bounds on the control variables. In this paper, our aim is to develop a computational method for the more general case of fixed-time problems with control constraints.     

太阳帆航天器地球逃逸轨道解析最优控制律

针对太阳帆航天器地球逃逸轨道控制问题,给出一种新的解析最优控制律.该控制律可使航天器在逃逸过程中轨道能量变化速率最大,从而保证逃逸时间最短.考虑到地球逃逸轨道形状,引入改进春分点轨道根数对航天器运动学方程进行描述,并给出了地球逃逸轨道最优控制律的推导过程.仿真分析表明,该控制律计算速度较快,而且可以根据航天器状态实时计算姿态控制角,因此比较适用于未来太阳帆航天器在轨自主控制系统.     

On-line optimal autonomous reentry guidance based on improved Gauss pseudospectral method

The on-line optimal autonomous reentry guidance of the hypersonic vehicle is proposed based on the improved Gauss pseudospectral method （IGPM）. The autonomous reentry guidance requires the hypersonic vehicle can generate the optimal trajectory for the latest flight mission on line and track the new trajectory well under the uncertainty. These two problems are simplified into a nonlinear optimal control problem with nonlinear constraints. The IGPM is introduced to solve the above two problems. The trajectory has to change according to the flight mission and therefore the new optimal trajectory can be obtained by IGPM within about 10 s. The optimal feedback guidance law is used to track the reference trajectory to handle the uncertainty. In order to deal with the CPU time delay, which comes from optimizing the new trajectory, the new on-line optimal autonomous reentry guidance is depicted. Finally, the numerical simulation shows that the proposed autonomous guidance can generate optimal trajectory for the new flight mission and have a high tracking accuracy     

Unprejudiced optimal open loop input design for identification of transfer functions

The problem to estimate transfer functions of linear systems is considered. The quality of the resulting estimate depends, among other things, on the input used during the identification experiment. We measure the quality using a quadratic norm in the frequency domain. The problem to determine optimal inputs, i.e. inputs that minimize the chosen norm, subject to constrained input variance, has long been studied. We point out that such procedures may involve a prejudice (that the system is to be found in a certain model set) that may have some surprising effects. We discuss how such a prejudice can be reduced by allowing the possibility that the true system cannot be exactly described in the chosen model set. We also calculate explicit expressions for the resulting “unprejudiced” optimal inputs. These expressions relate the signal-to-noise ratio (as a function of frequency) to the chosen weighting function in the quadratic norm. We also point out the role of the employed noise model for the design.     

Loop transfer recovery techniques for discrete-time optimal regulators using prediction estimators

For discrete-time LQG optimal regulators using current estimators, it has been shown that perfect recoveries of the loop transfer matrices at the input or at the output are possible for square minimum-phase systems. However, current estimators cannot be used when the processing time of the controller is significant. In this note, the loop transfer recoveries using prediction estimators for square minimum-phase systems are considered. It is shown that, although the perfect recoveries are impossible, the feedback properties obtained by the recovery techniques are those that can be recovered best in the presence of the delay in the controller.