Design and Analysis of Terminal Guidance Law for Kinetic Interceptors based on Pulse Engine

A new terminal guidance law is proposed based on a solid propellant pulse engine and an improved proportional navigation method to address the terminal guidance issue for kinetic interceptors.On this basis,the start-stop curve of the pulse motor during the terminal guidance process is designed,along with its start-up logic.The effectiveness of the proposed guidance strategy is verified through simulation.

Cooperative trajectory optimization of UAVs in approaching stage using feedback guidance methods

This paper mainly studies the problem of using UAVs to provide accurate remote target indication for hypersonic projectiles.Based on the optimal trajectory trends and feedback guidance methods,a new cooperative control algorithm is proposed to optimize trajectories of multi-UAVs for target tracking in approaching stage.Based on UAV kinematics and sensor performance models,optimal trajectory trends of UAVs are analyzed theoretically.Then,feedback guidance methods are proposed under the optimal observation trends of UAVs in the approaching target stage,producing trajectories with far less computational complexity and performance very close to the best-known trajectories.Next,the sufficient condition for the UAV to form the optimal observation configuration by the feedback guidance method is presented,which guarantees that the proposed method can optimize the observation trajectory of the UAV in approaching stage.Finally,the feedback guidance method is numerically simulated.Simulation results demonstrate that the estimation performance of the feedback guidance method is superior to the Lyapunov guidance vector field(LGVF)method and verify the effectiveness of the proposed method.Additionally,compared with the receding horizon optimization(RHO)method,the proposed method has the same optimization ability as the RHO method and better real-time performance.

Study on Numerical Comparison Method of Four-bar Straight-line Guidance Mechanism

In order to solve four-bar straight-line guidance mechanism synthesis problem for the arbitrarily given straight-line’s"angle requirement"and"point-position requirement",a numerical comparison synthesis method for single and double straight-line guidance mechanism is presented,which is convenient to realize by computer program.The basic idea of this method is:to select a four-bar linkage whose relative bar length of crank is 1 as a basic four-bar linkage.Then the other three relative bars’length is changed,and a lot of basic four-bar linkage can be obtained.There are many single and double ball-points of each basic four-bar linkage.With the motion of a basic four-bar linkage,there is straight-line segment of each Ball-point’s path.The data of these basic four-bar linkages is saved to a database.When designing a four-bar straight-line guidance mechanism,the design data is compared with the data in database and a satisfactory four-bar linkage can be obtained.The method effectively solves the straight-line guidance mechanism synthesis problem.

3-47 Reproducibility of Breathing Guidance Method for Respiratory Motion Management in Synchrotron-based Gated Heavy-ion Beam Delivery

A novel breathing guidance method by combining the personalized audio-visual biofeedback (BFB) system, the breath hold (BH) method, and the synchrotron-based gating technique have been developed to help patients synchronize their respiratory patterns with the synchrotron pulsed operation manner so as to overcome typical limitations such as low efficiency and residual motion[1;2]. This year we chose four fractions to evaluate the reproducibility of subject compliance with the breathing guidance maneuvers among different fractions for the breathing guidance technique.

Use of the Method of Guidance by a Required Velocity in Control of Spacecraft Attitude

We apply the method of guidance by a required velocity for solving the optimal control problem over spacecraft’s reorientation from known initial attitude into a required final attitude.We suppose that attitude control is carried out by impulse jet engines.For optimization of fuel consumption,the controlling moments are calculated and formed according to the method of free trajectories together with principle of iterative control using the quaternions for generating commands to actuators.Optimal solution corresponds to the principle“acceleration-free rotation-separate corrections-free rotation-braking”.Rotation along a hitting trajectory is supported by insignificant correction of the uncontrolled motion at discrete instants between segments of acceleration and braking.Various strategies of forming the correction impulses during stage of free motion are suggested.Improving accuracy of achievement of spacecraft's final position is reached by terminal control using information about current attitude and angular velocity measurements for determining an instant of beginning of braking(condition for start of braking based on actual motion parameters is formulated in analytical form).The described method is universal and invariant relative to moments of inertia.Developed laws of attitude control concern the algorithms with prognostic model,the synthesized control modes are invariant with respect to both external perturbations and parametric errors.Results of mathematical modeling are presented that demonstrate practical feasibility and high efficiency of designed algorithms.

Optimum Design of the Control System for a Laser Beam Riding Guidance Anti-Tank Missile

The optimum theory and methods were adopted to design the laser beam riding guidance anti tank missile's control system in the short run. Through building the mathematical model of system, selecting a proper method and taking advantage of computer's high speed calculation and logic traits, an optimal controller was designed. Simulation results showed that the designed control system has fair performance and it satisfies the tactical and technical requirements. The results also demonstrate that by the combination of the optimizing methods and the computer the control system could be designed as soon as possible.

STUDY OF OPTIMAL SLIDING-MODE GUIDANCE LAW

An optimal guidance law based on missile-target line-of-sight (LOS) angular rate is presented for intercepting a nonmaneuvering target. It is then integrated with sliding-mode control theory by using reaching-law of sliding-mode, in order to derive an optimal sliding-mode guidance law for intercepting a maneuvering target. The new guidance method's robustness against target maneuvers and good miss distance performance are proved by the second method of Lyapunov and simulation results. The presented guidance law is simple to implement in practical applications.

On“The Five-Step Method”in Teaching Junior English for China

Junior English for China’ is based on the ’Five-Step’ teachingmethod: Revision, Presentation, Drilling, Practice, Consolidation. Each step has itsown particular methodology and requires the teacher to adopt a certain role. Thispaper is a discussion of the "Five-Step Method".

Robust entry guidance using multi-segment linear pseudospectral model predictive control

This paper presents a robust entry guidance algorithm for the high lift-to-drag ratio entry vehicle that employs the recently developed pseudospectral model predict control in a segmented manner. Here, the guidance commands are the longitudinal lift-to-drag (L/D) and bank reversal commands, which are calculated by successively solving multiple segment linear algebraic equations. These equations are derived using the linear pseudospectral method, control parametrization and calculus of variations. The method uses orthogonal polynomials and computes the updates through a series of analytical formulae, which makes it accurate and computationally effective. Moreover, it is able to adjust the number of bank reversals by providing the precise bank reversal point so as to fully exploit the potential of lateral maneuver. The method also employs proportional navigation and polynomial guidance after the last bank reversal to meet multiple terminal constraints. High-fidelity numerical simulations with various destinations are carried out to demonstrate its applicability. Furthermore, Monte Carlo simulations are also conducted to show that the proposed algorithm consistently offers very stable and robust performances and has superior performances in computational efficiency, guidance accuracy and lateral trajectory shaping capability in comparison with other typical methods. © 1990-2011 Beijing Institute of Aerospace Information.

Modified attitude pursuit guidance law for low-cost missiles using strap-down seekers

Attitude pursuit guidance law is suitable for low cost missiles.A strap-down seeker is used to achieve this guidance law.The additional angles of attack or sideslip caused by wind and by control system are considered as two disturbing factors which make attitude pursuit law impossible.Therefore,general attitude pursuit guidance law did not account for this two disturbing factors,because with those disturbing factors,it is difficult to apply.To solve the problem,the principle of strap-down seeker detecting target is investigated,the mathematical control model is established,then a modified attitude pursuit guidance law which employs the angular correction for those two disturbing factors is presented.It is proved that the modified attitude pursuit guidance law is appropriated to both in the presence of the additional angle of attack or sideslip via the simulations with the mathematical control model and Monte-Carlo method.

Three-dimensional suboptimal guidance law for fly-over and shoot-down smart ammunition via virtual target

An optimal burst height is required for the fly-over and shoot-down smart ammunition with an EFP warhead at the instant of explosion which brings a special requirement to the miss distance of the terminal guidance law. In this paper, a guidance law based on the virtual target scheme is proposed. First, the practical pursuit-evasion issue between the ammunition and the target with specific miss distance is transformed into a virtuai pursuit-evasion problem with zero miss distance. Secondly, a complete three-dimensional pursuit-evasion kinematics model is established without any simplifications. And then, a suboptimal guidance law is designed based on the θ-D method which has constraints of the elevation and azimuth angular velocity of the virtual line of sight （LOS）. Finally, in order to verify the performance of the proposed guidance law, three test cases are conducted. Numericai results show that under the proposed terminal guidance law, the smart ammunition not only can fly above the target with an optimal burst height but also have a smaller normal acceleration on the terminal trajectory.

Kinetic Optimal Midcourse Guidance Law for Air-to-Air Missiles

A new kinetic optimal midcourse guidance law is derived based on optimal control formulation. A new simplified Runge-Kutta grade numerical method is proposed to find the optimal trajectory. Real data of an Mr-to-air missile is referred to for comparing results using the kinetic optimal midcourse guidance law with those under both the kinematic optimal guidance law and singular perturbation sub-optimal guidance law, wherein the latter two laws are modified in this paper by adding a vertical g-bias command to each law for the sake of trajectory shaping. Simulation results show that using the new kinetic optimal mideourse guidance law can help save energy and maximize terminal velocity effectively.

Adaptive Constrained On-board Guidance Technology forPowered Glide Vehicle

To make full use of expanded maneuverability and increased range,adaptive constrained on-board guidance technology is the key capability for a glide vehicle with a double-pulse rocket engine,especially under the requirements of desired target changing and on-line reconfigurable control and guidance.Based on the rapid footprint analysis,whether the new target is within the current footprint area is firstly judged.If not,the rocket engine ignites by the logic obtained from the analysis of optimal flight range by the method of hp-adaptive Gauss pseudospectral method(hp-GPM).Then,an on-board trajectory generation method based on powered quasi-equilibrium glide condition(QEGC)and linear quadratic regulator(LQR)method is used to guide the vehicle to the new target.The effectiveness of the guidance method consisted of powered on-board trajectory generation,LQR trajectory tracking,footprint calculation,and ignition time determination is indicated by some simulation examples.

CBL教学法结合“一对一”带教在儿童肺功能临床见习教学中的应用

目的:探索CBL教学法结合“一对一”带教在儿童肺功能临床见习教学中的应用效果。方法:将呼吸专科护士培训班46名学员随机分对照组和试验组,每组各23人,对照组采用传统教学方式,试验组采用CBL教学法结合“一对一”带教方式,比较两组学员肺功能考试成绩和教学效果主观评价情况。结果:试验组学员考试成绩和教学效果总体主观评价均明显高于对照组(P<0.05)。结论:在儿童肺功能临床见习教学中,应用CBL教学法结合“一对一”带教更有利于学员对理论教学内容的理解和掌握,提高临床应用能力,且学员对带教的满意度更高。

幼儿教师破解“隔代惯”的SZFJ方法

随着社会的快速发展,隔代教养日趋普遍,“隔代惯”问题也日益凸显。幼儿教师常常被动应对祖辈固化思想改变难、教养能力提升难、代际关系调和难、家园共育进退难等一系列“隔代惯”难题。运用案例分析法,探索并梳理破解“隔代惯”的四步流程,总结幼儿教师破解“隔代惯”的SZFJ方法,即“孙”为先、“祖”重点、“父”配合、“家”联结,以期为幼儿教师破解“隔代惯”、促进幼儿健康发展提供参考。

复杂行星表面着陆避障增广曲率制导方法

针对复杂行星表面安全着陆问题,提出避障增广曲率制导方法。在基本曲率制导律的基础上引入障碍规避增广项。该方法利用着陆器着陆空间区域划分的思想,在障碍附近易发生碰撞区域建立膨胀预警区,基于膨胀预警区推导连续解析的障碍规避制导律,在满足几何凸轨迹状态约束的同时,考虑着陆器与障碍的相对位置关系,能够快速引导着陆器远离障碍,提高着陆器着陆过程中的安全性。仿真结果表明,该方法能够有效规避复杂行星表面的地形障碍,实现在行星表面定点软着陆,具有良好的灵活性和可靠性。

Perturbed low-thrust geostationary orbit transfer guidance via polynomial costate estimation

This paper proposes an optimal,robust,and efficient guidance scheme for the perturbed minimum-time low-thrust transfer toward the geostationary orbit.The Earth’s oblateness perturbation and shadow are taken into account.It is difficult for a Lyapunov-based or trajectory-tracking guidance method to possess multiple characteristics at the same time,including high guidance optimality,robustness,and onboard computational efficiency.In this work,a concise relationship between the minimum-time transfer problem with orbital averaging and its optimal solution is identified,which reveals that the five averaged initial costates that dominate the optimal thrust direction can be approximately determined by only four initial modified equinoctial orbit elements after a coordinate transformation.Based on this relationship,the optimal averaged trajectories constituting the training dataset are randomly generated around a nominal averaged trajectory.Five polynomial regression models are trained on the training dataset and are regarded as the costate estimators.In the transfer,the spacecraft can obtain the real-time approximate optimal thrust direction by combining the costate estimations provided by the estimators with the current state at any time.Moreover,all these computations onboard are analytical.The simulation results show that the proposed guidance scheme possesses extremely high guidance optimality,robustness,and onboard computational efficiency.

天基引导对海打击杀伤链构建方法

针对远海作战条件下传统侦察手段保障对海精确打击受限的问题,提出一种基于天基侦察信息引导对海打击的杀伤链构建方法。明确天基引导对海打击杀伤链的基本定义,设计该杀伤链的一般作战流程;建立杀伤链模型,提出打击能力和闭合时间两类性能评估指标及其综合评估方法;设计了杀伤链的构建算法,可以遍历寻找打击每一个目标的所有杀伤链,并按照性能指标评估方法将杀伤链进行排序输出。在实验验证中,基于某作战想定生成了45种杀伤链结果,验证了该方法的合理性。

基于力引导的空间舱外双臂机器人遥操作同步过程优化

为提高空间舱外双臂机器人遥操作同步过程中操作效率,提出了一种基于力引导的遥操作同步过程优化方法。通过改进的蒙特卡洛法对双臂机器人协作的工作空间进行分析,提出了一种最优协作位置预测方法,并通过力引导方式,辅助引导遥操作双臂到达最优协作位置。实验结果表明:相比于只有视觉反馈的遥操作过程,同步过程优化后到达同步工作状态的时间减少了84.26%,同步过程通过的路径长度缩短了35.43%;对比运动学引导方法,各项指标方差更小,稳定性更强。

基于iCBCT分析前列腺癌调强放疗中的靶区位移

目的:研究iCBCT引导前列腺癌调强放疗中盆腔淋巴引流区和前列腺精囊腺靶区位移的差异性,为临床上选择合理的图像引导策略提供参考依据。方法:回顾性选取2023年01月至2023年09月在中山大学肿瘤防治中心进行调强放疗的21例前列腺癌患者,要求患者在定位及治疗前充盈膀胱、排空直肠,对患者治疗前扫描的iCBCT影像分别以盆腔骨性结构、前列腺精囊腺为参考进行离线配准(自动配准后手动调整),分别评估盆腔淋巴引流区、前列腺精囊腺的靶区位移误差,得到左右(left-right,LR)、头脚(superior-inferior,SI)和前后(anterior-posterior,AP)方向的位移数值,分析两个区域位移的差异性、相关性,并且计算相对位移,应用公式M_(PTV)=2.5Σ+0.7σ计算PTV外扩边界。结果:盆腔淋巴引流区、前列腺精囊腺在左右、头脚、前后平移方向位移误差分别为LR:(0.27±0.58)mm vs (0.31±0.61)mm;SI:(0.53±0.91)mm vs (0.68±0.98);AP:(2.03±1.86)mm vs (2.79±2.52)mm。头脚、前后方向位移差异有统计学意义(H=4.577、5.035,P<0.05),左右方向为高度相关(r=0.736),头脚方向为中度相关(r=0.542),前后方向为极低度相关(r=0.190)。两个区域在LR、SI和AP的相对位移5 mm的百分比分别为4.9%、5.3%和29.2%。盆腔淋巴引流区LR、SI、AP方向PTV外扩范围分别为1.08 mm、1.96 mm、6.38 mm,前列腺精囊腺LR、SI、AP方向PTV外扩范围为1.20 mm、2.39 mm、8.74 mm。结论:在前列腺癌调强放疗中,盆腔淋巴引流区和前列腺精囊腺靶区在分次治疗间前后方向位移较大,且两区域靶区在前后方向容易发生较大的相对位移,无法通过影像引导校正误差,应尽可能保持膀胱和直肠状态与CT定位时一致。