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Effects of ignition voltage and electrode structure on electric ignition and combustion characteristics of Ammonium Dinitramide(ADN)-based liquid propellants in electric ignition mode in inert gas environment

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Chinese Journal of Aeronautics 2024年第4期37卷 229-242页

作者： Lei LI Guoxiu LI Hongmeng LI Zhaopu YAO Tao ZHANG Jinze WU Shuo ZHANG School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Beijing Institute of Control Engineering Beijing 100190China

Hydrazine is toxic and carcinogenic, which greatly increases the difficulty of application and no longer meets the needs of green aerospace. As a green propellant, the Ammonium Dinitramide(ADN)-based liquid propellant has the advantages of higher specific impulse, being non-toxic,pollution-free, and easy storage. However, an ADN-based space engine in orbit has exposed the problems of high-temperature deactivation of catalysts and cold-start failure. An active ignition technology—electric ignition technology was explored in this paper to break through the technical bottleneck of catalyst deactivation and the inability to a cold start. An experimental system of a constant-volume combustor for the ADN-based liquid propellant based on the electric ignition method was established. The electric ignition and combustion characteristics of the ADN-based liquid propellant in a volume combustor with an electric ignition method were studied. The influencing mechanisms of the ignition voltage and the electrode structure on the electric ignition characteristics of the ADN-based liquid propellant were investigated. An elevation of the ignition voltage could facilitate the ignition process of the ADN-based liquid propellant, curtail electric energy input and heating effect, while exerting an adverse impact on the combustion process of the propellant.An increase in the ignition voltage enhanced the ignition process of the propellant while simultaneously suppressing its combustion process when utilizing mesh electrodes. Compared to the strip electrodes, the mesh electrodes increased the contact area between the electrodes and the propellant,increased the electric energy input power in the electric ignition process, and reduced the ignition delay time. The mesh electrodes could promote the combustion process of the propellant to a certain extent.

关键词： ADN-based liquid propellant Resistive ignition Electrical ignition characteristic Combustion Inert gas

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Integrated visual navigation based on angles-onlymeasurements for asteroid final landing phase

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Astrodynamics 2023年第1期7卷 69-82页

作者： Ronghai Hu Xiangyu Huang Chao Xu Beijing Institute of Control Engineering Beijing 100190China National Laboratory of Space Intelligent control Beijing 100190China

Visual navigation is imperative for successful asteroid exploration missions.In this study,an integrated visual navigation system was proposed based on angles-only measurements to robustly and accurately determine the pose of the lander during the final landing phase.The system used the lander's global pose information provided by an orbiter,which was deployed in space in advance,and its relative motion information in adjacent images to jointly estimate its optimal state.First,the landmarks on the asteroid surface and markers on the lander were identified from the images acquired by the orbiter.Subsequently,an angles-only measurement model concerning the landmarks and markers was constructed to estimate the orbiter's position and lander's pose.Subsequently,a method based on the epipolar constraint was proposed to estimate the lander's inter-frame motion.Then,the absolute pose and relative motion of the lander were fused using an extended Kalman filter.Additionally,the observability criterion and covariance of the state error were provided.Finally,synthetic image sequences were generated to validate the proposed navigation system,and numerical results demonstrated its advance in terms of robustness and accuracy.

关键词： asteroid final landing phase visual navigation angles-only measurements inter-frame motion estimation state fusion

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Adaptive dynamic programming-based fault-tolerant attitude control for flexible spacecraft with limited wireless resources

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Science China(Information Sciences) 2023年第10期66卷 213-228页

作者： Ming LIU Qiuhong LIU Lixian ZHANG Guangren DUAN Xibin CAO School of Astronautics Harbin Institute of Technology Beijing Institute of Control Engineering

This paper investigates the attitude control for flexible spacecraft subject to actuator faults and limited onboard communication resources. The control torque quantization scheme is considered between the controller and actuator to reduce the communication burden on the spacecraft. An integral sliding mode control method is designed to stabilize the closed-loop attitude control system and ensure the near-optimal performance of the sliding motion. First, an iterative learning observer scheme is employed to reconstruct the actuator faults and the unknown nonlinear flexible dynamics. Second, an integral sliding surface is combined with the backstepping control method to resolve the time-varying characterization of the closed system. Third, a combination of the adaptive dynamic programming technique and the adaptive single critic neural network approximation is employed to examine the optimal control policy. Finally, the efficacy of the proposed spacecraft attitude control method is demonstrated via a simulation.

关键词： flexible spacecraft fault-tolerant attitude control signal quantization adaptive dynamic programming neural network learning

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New method for multibody dynamics based on unknown constraint force

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Science China(Technological Sciences) 2024年第3期67卷 791-808页

作者： TIAN Ying JIA YingHong ZHANG Jun School of Astronautics Beihang UniversityBeijing 100191China Beijing Institute of Control Engineering Beijing 100190China National Laboratory of Space Intelligent control Beijing 100190China

This paper presents a new method for the dynamics of multibody systems based on unknown constraint force. The method can uniformly solve multibody systems with typical configurations, including the system with rigid-flexible coupling, the system in tree topology, and the system with loop constraints. Unlike common methods, the proposed method can model the loop system without “cutting off” loop constraints, leading to the exact same modelling process as the tree-like system performs. Based on graph theory, a topological record matrix M_(rec) is proposed to capture the arbitrary system configuration. Moreover, constraint forces are selected as the key variables in semi-recursive framework. With the recursive kinematics relationship between adjacent bodies, the constraint force equation is further assembled to achieve the full-state system solution. The numerical simulations demonstrate the accuracy of the proposed method.

关键词： multibody system dynamic modelling rigid-flexible coupling unknown constraint force graph theory semi-recursive algorithm

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Influencing factor analysis of interception probability and classification-regression neural network based estimation

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Journal of Systems engineering and Electronics 2023年第4期34卷 992-1006页

作者： NAN Yi YI Guoxing HU Lei WANG Changhong TU Zhenbiao Department of control Science and engineering Harbin Institute of TechnologyHarbin 150001China beijing Electro-mechanical engineering institute Beijing 100074China

The interception probability of a single missile is the basis for combat plan design and weapon performance evaluation,while its influencing factors are complex and mutually coupled.Existing calculation methods have very limited analysis of the influence mechanism of influencing factors,and none of them has analyzed the influence of the guidance law.This paper considers the influencing factors of both the interceptor and the target more comprehensively.Interceptor parameters include speed,guidance law,guidance error,fuze error,and fragment killing ability,while target performance includes speed,maneuverability,and vulnerability.In this paper,an interception model is established,Monte Carlo simulation is carried out,and the influence mechanism of each factor is analyzed based on the model and simulation results.Finally,this paper proposes a classification-regression neural network to quickly estimate the interception probability based on the value of influencing factors.The proposed method reduces the interference of invalid interception data to valid data,so its prediction accuracy is significantly better than that of pure regression neural networks.

关键词： interception probability simulation modeling analysis of influencing factors probability estimation neural networks

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A lightweight data-voting strategy for triple-modular redundant control computers

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Science China(Technological Sciences) 2022年第2期65卷 419-431页

作者： LIU Bo YANG MengFei WANG Yong YUAN Li LIU ChaoWei XU Jian YU Dan HU HongKai FENG Dan Beijing Institute of Control Engineering Beijing 100190China China Academy of Space Technology Beijing 100094China

Triple-modular redundancy(TMR), a well-known methodology for improving the reliability of computer systems, has been used for onboard control computers in many safety-critical space applications. In this paper, a lightweight data-voting strategy for TMR control computer is proposed, in which an additional straightforward input voting stage is added, so that determination of the maximum admissible deviation for output matching, as required by traditional strategies, can be avoided. The lightweight strategy is a practical data-voting solution for the TMR control computer that exploits the characteristics of the data of the control computer. The addition of input voting, in both the value and time domains, can ensure that the outputs of non-faulty machines are exactly equal, and the bitwise output matching of the TMR control computer can be performed. The new data-voting strategy has been optimized according to the actual application conditions in spacecraft control systems, and has been adopted for the TMR control computer of the Chang’e-5 Return Spacecraft. The results of the ground experiments and successful on-orbit application have demonstrated the advantages of the new data-voting strategy for TMR control computer.

关键词： TMR data-voting onboard control computer output matching

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Study on the method of precision adjustment of star sensor

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Nanotechnology and Precision engineering 2018年第4期1卷 248-257页

作者： Xiaoyan Wang Ran Zheng Yanpeng Wu Jianbo Sun Jun Zhong Long Wang Miaomiao Wang Beijing Institute of Control Engineering Beijing 100190China

Star sensors are indispensable spatial measurement sensors for high-resolution earth observation and astronomical observations, and the demand for high measurement accuracy of satellite sensors continues to increase; thus, the star sensor optical machine adjustment error cannot be ignored. The commonly used installation error correction method cannot solely meet the precision analysis requirements. In this paper, the relationship between the optical machine installation and the star sensor measurement error is analyzed, and several common adjustment error correction methods are compared. An adjustment method for optical machines is proposed to meet the requirements of very high precision star sensors. The assembly precision requirements of the investigated very high precision star sensor are analyzed considering the whole machine, and then the optical components are controlled through optical precision adjustments to satisfy the precision requirements. Finally, through the complete machine calibration, the star sensor precision adjustment for an optical machine structure is verified. This method meets the requirements of very high precision sensors and is suitable for the precision adjustment of optical machine structures, which is of practical significance to improve the precision of star sensors.

关键词： Very high precision star sensor Optical machine structure Alignment precision Precision adjustment

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Toward the recognition of spacecraft feature components:A new benchmark and a new model

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Astrodynamics 2022年第3期6卷 237-248页

作者： Linwei Qiu Liang Tang Rui Zhong School of Astronautics Beihang UniversityBeijing 100191China Key Laboratory of Space Intelligent control Technology Beijing Institute of Control EngineeringBeijing 100094China

Countries are increasingly interested in spacecraft surveillance and recognition which play an important role in on-orbit maintenance,space docking,and other applications.Traditional detection methods,including radar,have many restrictions,such as excessive costs and energy supply problems.For many on-orbit servicing spacecraft,image recognition is a simple but relatively accurate method for obtaining sufficient position and direction information to offer services.However,to the best of our knowledge,few practical machine-learning models focusing on the recognition of spacecraft feature components have been reported.In addition,it is difficult to find substantial on-orbit images with which to train or evaluate such a model.In this study,we first created a new dataset containing numerous artificial images of on-orbit spacecraft with labeled components.Our base images were derived from 3D Max and STK software.These images include many types of satellites and satellite postures.Considering real-world illumination conditions and imperfect camera observations,we developed a degradation algorithm that enabled us to produce thousands of artificial images of spacecraft.The feature components of the spacecraft in all images were labeled manually.We discovered that direct utilization of the DeepLab V3+model leads to poor edge recognition.Poorly defined edges provide imprecise position or direction information and degrade the performance of on-orbit services.Thus,the edge information of the target was taken as a supervisory guide,and was used to develop the proposed Edge Auxiliary Supervision DeepLab Network(EASDN).The main idea of EASDN is to provide a new edge auxiliary loss by calculating the L2 loss between the predicted edge masks and ground-truth edge masks during training.Our extensive experiments demonstrate that our network can perform well both on our benchmark and on real on-orbit spacecraft images from the Internet.Furthermore,the device usage and processing time meet the demands of engineering applications.

关键词： spacecraft deep learning feature components semantic segmentation

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Constrained Moving Path Following control for UAV With Robust control Barrier Function

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IEEE/CAA Journal of Automatica Sinica 2023年第7期10卷 1557-1570页

作者： Zewei Zheng Jiazhe Li Zhiyuan Guan Zongyu Zuo Seventh Research Division School of Automation Science and Electrical EngineeringBeihang UniversityBeijing 100191 Beijing Institute of Control Engineering Beijing 100094China

This paper studies the moving path following(MPF)problem for fixed-wing unmanned aerial vehicle(UAV)under output constraints and wind disturbances.The vehicle is required to converge to a reference path moving with respect to the inertial frame,while the path following error is not expected to violate the predefined boundaries.Differently from existing moving path following guidance laws,the proposed method removes complex geometric transformation by formulating the moving path following problem into a second-order time-varying control problem.A nominal moving path following guidance law is designed with disturbances and their derivatives estimated by high-order disturbance observers.To guarantee that the path following error will not exceed the prescribed bounds,a robust control barrier function is developed and incorporated into controller design with quadratic program based framework.The proposed method does not require the initial position of the UAV to be within predefined boundaries.And the safety margin concept makes error-constraint be respected even if in a noisy environment.The proposed guidance law is validated through numerical simulations of shipboard landing and hardware-in-theloop(HIL)experiments.

关键词： Moving path following(MPF) robust control barrier function safety margin shipboard landing unmanned aerial vehicle(UAV)

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Novel objects 3-D dense packing through robotic pushing

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Science China(Technological Sciences) 2022年第12期65卷 2942-2951页

作者： WU JianHua ZHANG HaoDong CHANG YaFei XIONG ZhenHua ZHU XiangYang institute of Robotics School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Beijing Institute of Control Engineering Beijing 100190China

Robotic picking and placing systems can increase the flexibility of packing objects in a box and are attractive in many fields.However,owing to inevitable uncertainties in both the picking and placing stages,the objects cannot be placed at desired positions accurately and hence cannot be packed densely.This paper presents an additional pushing action that maximizes the packing density;i.e.,after being released from the robot end,the object is moved by robotic pushing actions to arrange the packing densely.The robotic pushing strategy is determined through a deep reinforcement learning algorithm.The idea is to compress the objects toward a corner to improve the volume utilization rate by minimizing the result of a heuristic score.The learning process is implemented in simulation and the trained network is transferred to a robot system directly.Simulations and experiments are presented for the packing of regular and irregular objects to verify the proposed method.

关键词： robotic pushing three-dimensional packing reinforcement learning

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