Jul 2023, Volume 10 Issue 2
    

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  • Topic: Celestial Navigation Technology for Deep Space Exploration
    The Progress of Autonomous Celestial Navigation for Deep Space Spacecraft
    NING Xiaolin, YANG Yuqing, FANG Jiancheng, WU Weiren
    2023, 10(2): 99-108. https://doi.org/10.15982/j.issn.2096-9287.2023.20230023
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    In response to the urgent needs of deep space explorer for autonomous celestial navigation，this paper briefly introduces the research status of autonomous celestial navigation methods and summarizes the problems faced by current autonomous celestial navigation methods. As the error sources of the celestial navigation system is multiple and time-varying，two error suppression technologies based on augmented filtering and differential are expound in detail. In view of the limitations of the existing autonomous celestial navigation methods，the autonomous celestial integrated navigation methods are introduced in detail. Finally，the future development trend of the celestial navigation method for the deep space spacecraft is prospected.
  • Topic: Celestial Navigation Technology for Deep Space Exploration
    Autonomous Navigation Method of Spacecraft in Libration Point Orbit Based on Space Objects Observations
    LIANG Fei, WANG Yidi, ZHENG Wei
    2023, 10(2): 109-116. https://doi.org/10.15982/j.issn.2096-9287.2023.20230015
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    In order to achieve the autonomous operation of spacecraft in the Earth-Moon libration point orbits，an autonomous navigation method using space objects observations was proposed in this paper. Space objects refer to the catalogued space targets orbiting the Earth. In this method，the motion states of spacecraft can be estimated according to the angles between the spacecraft and space objects. Firstly，the constraints of star sensor field of view，earth occlusion and solar interference were analyzed，and Beidou satellites for observation are selected. Next，Fisher information matrix was adopted to analyze the observability of the system，and the optimal observation targets were selected based on the observability analysis results. Finally，spacecraft in Earth-Moon libration point orbit were selected to verify the feasibility of the proposed autonomous navigation method. The simulation results show that the positioning accuracy of the proposed method can converge to less than 1km when the simulation time are 20 hours.
  • Topic: Celestial Navigation Technology for Deep Space Exploration
    An Adaptive Kalman Filter for Mars Spacecraft Approach Phase
    XIE Tianhao, ZHANG Wenjia, MA Xin, NING Xiaolin
    2023, 10(2): 117-125. https://doi.org/10.15982/j.issn.2096-9287.2023.20230014
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    Celestial navigation technology is a kind of navigation means which is suitable for deep space exploration. It has been widely used in deep space exploration field. In the practical operation of deep space detector, Kalman filter is usually used as the optimal estimation method due to the existence of process noise and measurement noise. When deep space probe is in the approach section of the orbit, the acceleration of the probe changes sharply, which leads to the increase of the uncertainty of the navigation system process noise, so the process noise covariance cannot be accurately known. To solve these problems, adaptive Q cubature Kalman filter (AQCKF) based on system noise covariance adjustment was proposed in this paper. In this method, the estimated covariance of process noise at the last moment and the observed covariance of process noise at the present moment were considered comprehensively. The method used the weighted factor to adjust noise covariance online, which made the filtering method more optimized. At the same time, in this paper was taken the Mars probe as an example to be simulated. Simulation results show that compared with Cubature Kalman Filter (CKF), the average position error of AQCKF method was 10.2359 km, and the average velocity error was 0.3224 m/s.This method can not only solve the problem of error divergence, but also improve the stability of navigation system. In addition, the paper also analyzes the influence of weighted factor on navigation performance, which can effectively solve the problem of navigation accuracy reduction when deep space probe is in the approach segment.
  • Topic: Celestial Navigation Technology for Deep Space Exploration
    Celestial Angle Measurement Navigation for Mars Probe Considering Relativistic Effect
    GUI Mingzhen, WEI Yifeng, NING Xiaolin
    2023, 10(2): 126-132. https://doi.org/10.15982/j.issn.2096-9287.2023.20230001
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    Celestial navigation based on star angle is a classical autonomous navigation method for spacecraft. By measuring the angular relationship between spacecraft，near celestial bodies and background stars，the current position and velocity information of spacecraft can be deduced. However，the effect of general relativity causes the starlight from a star to be somewhat deflected as it passes through a massive object，and special relativity allows high-speed spacecraft to observe stellar aberration. These two factors will cause the difference between the actual measurement of spacecraft and the corresponding information in the ephemeris，and then affect the navigation accuracy. To solve this problem，a celestial navigation method considering relativistic effect was proposed in this paper. The star angle measurement model is correct by relativistic effect to conform to the actual observation result，so as to improve the navigation accuracy. The simulation result shows that the proposed method can effectively correct the influence of relativistic effect on spacecraft star angle navigation in Mars surrounding orbit. When the star sensor measurement error is 3″ and the Mars sensor measurement error is 0.05°，the corrected average position error and average velocity error are reduced by 13.97% and 13.89% respectively，compared with the uncorrected case.
  • Topic: Celestial Navigation Technology for Deep Space Exploration
    Landmark Selection Method for Autonomous Optical Navigation Based on Depth Estimation Error
    LI Jiaxing, WANG Dayi, DONG Tianshu, LI Maodeng, XU Chao
    2023, 10(2): 133-139. https://doi.org/10.15982/j.issn.2096-9287.2023.20230019
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    When autonomous optical navigation is used to achieve accurate planetary landing，the amount of computation required for landmark selection needs to be reduced due to the limitation of computational resources. In this paper，a depth estimation error-based landmark selection method was proposed. First，a depth estimation error model was developed to describe the accuracy of distance estimation between the lander and the landmark when the same landmark was observed twice in a row，and then the model was used to describe observability degree and to select the landmark with highest accuracy of line-of-sight depth estimation from the sequential images. The landmark selection method proposed in this paper is similar to the conventional methods in terms of navigation accuracy，but requires less optimization computation time and is more suitable for autonomous navigation on the lander.
  • Topic: Celestial Navigation Technology for Deep Space Exploration
    Relativistic Navigation Method for Deep Space Probes
    XIONG Kai, WEI Chunling, LI Liansheng, ZHOU Peng
    2023, 10(2): 140-150. https://doi.org/10.15982/j.issn.2096-9287.2023.20230011
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    An autonomous navigation method based on the observations of the relativistic perturbations for deep space probes is presented in this paper. The relativistic perturbations including the stellar aberration and the starlight gravitational deflection are new type of celestial navigation measurement，which can provide the kinematic state information of the deep space probes in the inertial frame. In the relativistic navigation system，the position and velocity vectors of the deep space probes，and the measurement bias of the optical sensor can be estimated through measuring the inter-star angle perturbed by the stellar aberration and the gravitational deflection of light with an optical sensor for LOS (line-of-sight) direction with extremely high accuracy. In this paper，the state equation and measurement equation for the design of the navigation filter and the navigation performance evaluation are established. The feasibility of the relativistic navigation method for deep space probes is investigated via the calculation of the Cramer-Rao Lower Bound (CRLB). In addition，the self-learning strategy of the navigation filter is designed to enhance the relativistic navigation performance. It is illustrated through the numerical simulation that，for a Mars-circling probe，the position error of the relativistic navigation method is on the order of 100 m with the inter-star angle measurement accuracy of 1 mas.
  • Topic: Celestial Navigation Technology for Deep Space Exploration
    Pulsar Positioning and Velocimetry Method Based on Sparrow Search Algorithm-Optimized Quantum CS
    WU Daliang, LIU Jin, WU Jin, NING Xiaolin, KANG Zhiwei
    2023, 10(2): 151-158. https://doi.org/10.15982/j.issn.2096-9287.2023.20230003
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    The size of the quantum measurement matrix in the Quantum based CS (QCS) of X-ray pulsar positioning and velocimetry method is large. To reduce calculation time, a fast Quantum-CS method based on the Sparrow Search Algorithm optimization (SSA-QCS) was proposed and applied to the pulsar positioning and velocimetry. The quantum measurement mother matrix in QCS was divided into multiple sub-matrices. The quantum measurement sub-matrices were selected from the quantum measurement mother matrix through SSA. With the location of every sparrow corresponding to the combination of quantum measurement sub-matrices, with the estimation errors of the positioning and velocimetry in QCS as the object of the fitness function, through iterations, the optimal combination of the quantum measurement sub-matrices was obtained, forming a small-sized and high-performance quantum measurement matrix. Simulation results show that the SSA-QCS has a lower calculation cost and higher accuracy compared with the QCS. SSA-QCS can reach high-accuracy and real-time X-ray pulsar positioning and velocimetry.
  • Topic: Celestial Navigation Technology for Deep Space Exploration
    An Autonomous Navigation Method for Spacecraft in Cislunar Space Using Stellar Aberration Observation
    LIU fucheng, LI Muzi, PENG Yang, SUN Jun, LIU Jingxi
    2023, 10(2): 159-168. https://doi.org/10.15982/j.issn.2096-9287.2023.20220109
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    Exploration and utilization of the cislunar space is of great significance to the future development of human society. In order to improve navigation efficiency and survivability of spacecraft in cislunar space and reduce the burden of ground measurement and control，an autonomous navigation method only using star imagery was presented. In the method，the observation model was constructed based on stellar aberration effect. With the help of the orbit dynamic model and an extended Kalman filter，spacecraft orbit was estimated. For the problems of gravitational field interference from large celestial bodies and navigation accuracy decline under the constraints of small field of view，a gravitational field processing model based on dynamical model prediction and a multi-field collaborative observation method were proposed. Finally，the Monte-Carlo simulation results demonstrate the feasibility of the proposed method，and show that a navigation precision RMS better than 3 km and 0.2 m/s can be achieved.
  • Research Papers
    Stiffness Analysis and Error Compensation of Lunar Sampling Manipulator
    ZHANG Yundong, LIU Chuankai, HUANG Kaiqi, SU Jianhua, CHEN Gang, ZHANG Kuan
    2023, 10(2): 169-177. https://doi.org/10.15982/j.issn.2096-9287.2023.20220096
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    In the lunar surface sampling mission, the lunar sampling manipulator, due to the flexibility of its boom and joints, has low stiffness, which leads to the reduction of manipulator control accuracy. To address the above problem, in this paper, an end-operation error compensation method was proposed based on the estimation of flexible deformation of the manipulator, and an overall stiffness model of the multi-degree-of-freedom manipulator was constructed by analyzing joint flexibility, arm rod flexibility and self-weight and other factors on joint flexibility of the end position of the manipulator. The error bounds for the end position estimation of the manipulator under different configuration conditions were given. On this basis, a one-time compensation control method for the end operation of the manipulator was designed, which can reduce the maximum control deviation of the end of the robotic arm from 35 mmto less than 1 mm, greatly improving the absolute positioning accuracy of the lunar sampling manipulator simulation system.
  • Research Papers
    Conception of Integrated Scheme of “Exploration, Mining and Utilization” of Lunar Water-Ice Resources
    ZHOU Guangxu, CUI Zhongyu, ZHANG Weiwei, JIANG Shengyuan, GUO Linli
    2023, 10(2): 178-189. https://doi.org/10.15982/j.issn.2096-9287.2023.20220009
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    Four key technologies and solutions were summarized four key technologies and solutions：accurate prediction of water ice resources，scientific in-situ analysis，efficient extraction，and its transformation and utilization. For the demand of the detection and utilization of water ice resources in the polar regions of Moon，taking advantage of the deep low temperature and occurrence characteristics of water ice in the lunar polar regions，an integrated scheme of “Detecting，Mining and Utilization” on lunar water-ice resources was this paper proposed，and the application scenarios and functions，design plans and evaluations，application prospects，etc. The project provides technical reference and a scientific basis for future exploration，development and utilization of water ice resources in lunar polar regions，support for China’s fourth lunar exploration project and lunar scientific research station construction and other major missions.
  • Research Papers
    Foot-Soil Slipping Performance of Footed Robot in Soft Geology on Lunar Surface
    ZHONG Shiying, YUE Qianqian, LING Daosheng, ZHOU Hao, HAN Runqi, CONG Bori
    2023, 10(2): 190-198. https://doi.org/10.15982/j.issn.2096-9287.2023.20220036
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    Mobile robot is the backbone of the way of the lunar exploration，its foot end force is an important parameter for gait control. In order to study the effect of foot pattern design on foot-soil interaction in loose lunar soil on the anti-slip performance of the foot end, the anti-slip performance of three foot end pattern configurations was studied：triangle，arc and rectangle. The anti-slip performances of different pattern configurations under the same vertical load were studied through numerical simulation，and the anti-slip parameters of each pattern configuration were obtained through the equivalence principle. The results show that before the foot end pattern is completely pierced into the lunar soil，the circular arc pattern has the smallest settlement amount under the same vertical load，followed by the rectangular pattern with the triangular pattern having the largest settlement amount pattern under the same vertical load. At the same time, the slippage and stress peak of the circular arc pattern are also minimal. Under the anti-slip model of foot-soil contact surface，the equivalent shear strength of the rectangular pattern is the greatest when the same amount of subsidence is the largest，the equivalent friction angle is 33.44°，and the cohesion force 2.58 kPa，the circular arc pattern is the smallest，and its equivalent friction angle is 30.16° and the cohesion force 2.48 kPa.
  • Research Papers
    Simulation of Icy Lunar Regolith and Experiment on Its Shear Strength
    JI Jie, WANG Xiaoguang, XIAO Junxiao, XIAO Tao, ZHANG Weiwei, WANG Chu, MA Jinan, LIU Yafang, SUN Jing, JIANG Shengyuan
    2023, 10(2): 199-210. https://doi.org/10.15982/j.issn.2096-9287.2023.20230006
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    In order to obtain the shear strength of Icy Lunar Regolith (ILR) in the Permanently Shadowed Region (PSR) of the Moon, the physical properties of ILR such as mineral composition, particle size distribution, dry density, water content and deposition temperature were analyzed, and a method for ILR simulant preparing and parameters testing was proposed. Based on the Variable-Angle Shear Test (VAST) method, shear strength tests of ILR simulant were conducted with a mixed raw material made of anorthosite and basalt, dry density of 1.71g/cm3 (i.e. 100% relative density), water content from 3.7 wt% to 9.5 wt%, and temperature below –180°C. The result shows that the shear damage mode of the ILR simulant under low confining pressure is dominated by brittle fracture on the shear surface, but with the increase of the confining pressure, the brittleness of the ILR decreases and the ductility increases. In this case, its damage mode changes to compression-shear damage, and the shear strength decreases. The shear strength parameters of the ILR simulant under low confining pressure were calculated according to the linear Mohr-Coulomb criterion. The results show that the cohesion increases linearly with the increase of water content, but the internal friction angle hardly varies with water content, with values between 50° and 53°.
  • Research Papers
    Single-Beam Differential Relative Navigation of DRO Satellite Formation
    LI Shuanglin, PU Jinghui, GUO Pengbin, WANG Wenbin, ZHANG Wei
    2023, 10(2): 211-219. https://doi.org/10.15982/j.issn.2096-9287.2023.20230016
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    This paper proposes a single-beam differential relative navigation method to solve the relative navigation requirements of Distant Retrograde Orbit (DRO) satellite formation in cislunar space. The formation of two DRO satellites can be covered by a beam of measurement sent by a Low Earth Orbit (LEO) satellite, thus establishing two Satellite-to-Satellite Tracking (SST) links with the LEO satellite at the same time. Then differential measurement data can be obtained by these two SST links. This method can get relative states of the DRO satellite information by combining the differential measurement data and three-body orbital dynamics model. DRO is in the space with high asymmetry of the Earth-Moon three-body gravitational field, according to the LiAISON principle, a SST link established between the satellite running on this orbit and an LEO satellite can realize autonomous navigation, thus determining the absolute orbit states of one of the DRO formation satellites and the LEO satellite. The single-beam differential relative navigation method uses the absolute states of two satellites as constraints, and the advantage of using differential measurement data to eliminate common errors can obtain high-precision relative states of DRO satellite formation. In the simulation test, the relative navigation performance of the single-beam differential relative navigation method of the short-distance DRO satellite formation (inter-satellite distance of 50 km) and the long-distance DRO satellite formation (the distance between the satellites is about tens of thousands of kilometers) is tested. And the results show that, when the inter-satellite ranging noise is 0.5 m, the relative navigation accuracy calculated by the method proposed in this paper is 5 m (1 σ), which is 4 times higher than the relative navigation accuracy calculated by differencing the absolute orbit.
  • Research Papers
    An Autonomous Planning Method for Deep Space Exploration Tasks in Reinforcement Learning Based on Dynamic Rewards
    MAO Weiyang, WANG Bin, LIU Jingxing, XIONG Xin
    2023, 10(2): 220-230. https://doi.org/10.15982/j.issn.2096-9287.2023.20220049
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    Aiming at the characteristics of multi-system parallelism and the need to meet various constraints in the proceAiming at the characteristics of multi-system parallelism and the need to meet various constraints in the process of autonomous mission planning of deep space detectors, a reinforcement learning task autonomous planning model construction method for deep space detectors was proposed based on dynamic rewards, and a deep space detector agent was established. In the interactive environment, a policy network and a loss function integrating resource constraints, time constraints and timing constraints were constructed, and a dynamic reward mechanism was proposed to improve the traditional policy gradient learning method. The simulation results show that the method in this paper could realize autonomous task planning. Compared with the static reward policy gradient algorithm, the planning success rate and planning efficiency were significantly improved, and the method could start planning in any state without changing the model structure, which improved the accuracy of the algorithm. This method provides a new solution for autonomous mission planning and decision-making of deep space probes.