Chinese Version Light学术出版中心
Latest Issue
Issue 12z ， 2017
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Development trend of optical navigation sensor technology for asteroid exploration
Abstract：With the advancement of human ability to space exploration, deep space exploration has become a worldwide hot issue in the field of aerospace. In China, asteroid exploration has been involved in the four major tasks of future deep space exploration project. Navigation sensor technology, acting as a research focus in the field of exploration, plays an important role in improving the efficiency of ground measurement and control, enhancing the survivability of probes and completing the positioning task requirements. The paper reviews mission plans for deep space exploration of small celestial bodies and their navigation sensor configurations at home and abroad. The navigation methods and sensor functions of the detector in interplanetary cruise phase, approach interphase phase, flying around inspection phase and falling landing phase are summarized. In addition, the research achievements of existing navigation sensor systems are recapitulated. Finally, the development trend of asteroid detection navigation sensors is summarized and some suggestions and considerations on asteroid navigation technology in China are provided.Keywords：asteroid exploration;navigation sensors;development trend- 54
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Published：2020-08-13 -
Design of super-twisting controller for rotor vehicle based on high-order sliding mode observer with laser rangefinder
Abstract：Unmanned aerial vehicles (UAVs) carrying a laser rangefinder can provide more accurate aircraft height information than conventional GPS or barometer measurements in actual flights, however, they can't provide the altitude velocity. This article addresses the problem of altitude tracking of aircrafts and proposes a control strategy based on the combination of a high-order sliding mode observer and a super-twisting sliding mode controller, which can respectively control and estimate the altitude velocity. First, the dynamic model of altitude direction of a rotor aircraft is established, then the high-order sliding mode observer is established to estimate state variables, and the super-twisting controller is designed. Then, a comprehensive stability analysis of the combined controller-observer based on the Lyapunov stability theory is presented, thus ensuring the asymptotic convergence of the tracking error under external bounded disturbances. The experimental results show that the super-twisting sliding mode controller can evaluate the altitude velocity accurately by using the information output from the high-order sliding mode observer, and the convergence time is 0.5 s. The combination of the super-twisting controller and high-order sliding mode observer can realize the accurate altitude control of aircrafts.Keywords：laser rangefinder;high-order sliding mode observer;super-twisting controller;unmanned aerial vehicles- 79
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Published：2020-08-13 -
Refractive-diffractive optical imaging system for satellite-borne surveillance of space targets
Abstract：In order to monitor space targets and space debris, a refractive-diffractive optical imaging system with wide field of view and large relative aperture was designed. Parameters and working principle of the system, as well as the way of achromatic and athermal design based on the refractive-diffractive lens was studied. Firstly, the structure and principle of the space target surveillance system were introduced, and the design parameters of the optical system were established according to the requirements. Then, the optical system was optimized via refractive-diffractive lens, including focal zoom, adjustment of aperture and field, aberration correction and etc. The performance of the system was further optimized by the analysis of system encircled energy, RMS radius of spot diagram, MTF, color and distortion aberration. Finally, the values of MTF at different temperatures were analyzed. The results indicate that the system exhibits a total length of 63.4 mm, field of view of 25°×25°, focal length of 32.33 mm and clear aperture of 20.2 mm. With the refractive-diffractive lens, the lateral color is -0.828 μm. The MTF values of all field are above 0.6 at the temperature of -50, 20, 70℃. The refractive-diffractive optical imaging system can achieved achromatism and athermalization, thus its imaging performance is stable and fine.Keywords：optical design;refractive-diffractive lens;space target surveillance;wide field of view- 42
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Published：2020-08-13 -
Design of deployable solar array for agile optical satellite
Abstract：In view of the requirement of deployable solar array with high stiffness lead by dynamic imaging in agile optical satellites, a deployable solar array based on truss stiffener was established with components in high technology readiness level and product readiness level. The design of the deployable solar array involved the transition from open loop mechanism to close loop mechanism, the transformation of fundamental mode of vibration by changing the deployed structure, and sufficient reinforcement of the panel. Furthermore, the scheme was optimized via mechanism analysis. The results indicate that the deployable solar array allows a 4.5 s stable deployment without any interference, and the deployment and lock-in mechanism is feasible and stable. The fundamental mode of vibration is torsion with 6.1 Hz frequency. This deployable solar array can satisfy the requirement of agile optical satellites.Keywords：agile optical satellite;deployable;solar array;truss stiffner- 41
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Published：2020-08-13 -
High-precision test station for stray light based on point source transmittance
Abstract：The increased demand for detection of dim targets in deep space and the rapid development of low threshold space-based sensors have required greater suppression performance of stay light and higher test accuracy. A stray light test station based on Point Source Transmittance (PST) is built. The station allows an measuring aperture up to 1 m and waveband from the visible to the infrared. In the station, the turntable instrument is allowed to scan ±110° in azimuth, and ±15° in picth. The test station is all black with dimensions of 28 m×8 m×9 m. In order to control light scattered from the collimator, the primary mirror with less than 2 nm RMS roughness is manufactured. A double cylindrical chamber is employed to direct and attenuate the scattered light from the system. In addition, a clean room in 1 000 class is utilized to filter air to reduce light scattered from particles in the air. Analysis and measurements show that the test station can measure point PST as low as 10-7 at visible wavelengths, and 10-6 at infrared wavelengths. Its test accuracy|lg(measurement value/true value)|is less than 0.5.Keywords：space optics;stray light;light pollution;point source transmittance- 65
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Published：2020-08-13 -
Development and error estimation of centroid measurement system for planet rover
Abstract：In order to realize low gravity compensation experiment of a overhung planet rover and understand the centroid variation of the planet rover in different working conditions, a planet rover centroid measurement system was designed. The system can measure the centroid position of the planet rover under different working conditions by one on-line measurement and one auxiliary measurement. Firstly, a centroid measurement system for planet rover was developed, which was mainly composed of six sets of height-adjustable and joint arm type electronic scale measuring unit. Combined lifting method with tilting-platform method, the rover centroid was calculated by measuring the pressure of every wheel in different operating conditions with every electronic scale. Secondly, the measuring steps and methods of the system were described. The calculation model of centroid position vector and its coordinate components were derived based on the measurement of every wheel pressure. Thirdly, the error of the measurement system was analyzed, including systematic error, random error and accidental error, and the measures to eliminate or reduce the errors were proposed. Moreover, the systematic errors caused by sensor measurements were quantitatively analyzed. The results show that the maximum measurement error in each direction is 0.694, 0.163 and 0.255 mm respectively, and the overall error is less than 0.757 mm. The proposed system can meet the planet rover center of mass measurement accuracy requirements in different working conditions.Keywords：planet rover;centroid measurement;electronic scale;joint arm type;error analysis- 44
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Published：2020-08-13 -
Integrated guidance and control for reusable launch vehicle
Abstract：In order to assure the automatic re-entry ability for next generation Reusable Launch Vehicle (RLV), and avoide the failure lead by breakdown of actuators, an integrated guidance and control system was established. And its applied algorithms such as backstepping guidance, control allocator, model following prefilter, anti-windup and etc were investigated. First, backstepping guidance algorithm was deduced based on entry dynamics and kinematics. Actuators control allocator was analyzed by utilizing the dynamic inverse theory, thus computing the pseudo-inverse matrix based on moments command to reassign actuator commands. Then the algorithm of prefilter by guidance commands following was analyzed to improve the system robustness for model errors. Finally, the method of reference model bandwidth attenuation and integrator anti-windup were discussed. Experimental results indicate that the success ratio of re-entry is 77% and the precision of the control error is within 0.1°. The integrated system can satisfy the system requirements of higher precision and robustness, and increase re-entry safety while RLV's actuators failed to work normally.Keywords：Reusable Launch Vehicle (RLV);actuator failure;backstepping guidance;control allocator;model following;anti-windup- 53
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Published：2020-08-13 -
Design of light flexible carbon fiber boom for satellite
Abstract：In order to provide space deployable mechanism with light weight, small size, high folded and deployable reliability, and high repeated deployment precision for the mother satellite and daughter satellite in the Deployable Payload Space Science Mission (DPSSM), a light flexible carbon fiber boom was designed. In terms of the characteristic of the satellite combination configuration, the overall layout of folded and deployable boom was optimized. The configuration of the carbon fiber boom was designed based on mechanism integration method. With U-shaped hole tapped on the carbon fiber boom, flexible joints were obtained. The analysis methods of layer number and layer angle were combined to determine the carbon fiber composite material. Modal, deployment, overload and random vibration of the light flexible carbon fiber boom were simulated with real mechanics environment. In addition, several experiments were performed on the boom, including stretching test, bending test, torsional test, ground unfolding tests and repeated deployment precision test. The results indicate that the repeated deployment precision of the boom is better than 0.018°, and the base frequencies of the deployable and folded boom are higher than 4 Hz and 150 Hz respectively. The light flexible carbon fiber boom basically meets the requirements of launching, thus is feasible in real space science missions.Keywords：carbon fiber;flexible boom;configuration design;repeated deployment precision- 53
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Published：2020-08-13 -
Path planning for minimizing base disturbance of free-floating space robot
Abstract：In order to minimize the base attitude disturbance while free-floating robots captures targets, an optimal path planning method based on Gauss pseudospectral method was proposed. Firstly, the kinetic and dynamical models of space manipulator were established based on space multi-rigid-body dynamics. Then, the optimal control problem was employed to describe the path planning problem for minimum base disturbance, and the optimal control problem was discretized on a series of LG (Legendre-Gauss) points based on the Gauss pseudospectral method, and the optimal control problem was transformed into nonlinear programming problem. Finally, the designed path planning method was simulated by using a planar two degree-of-freedom space manipulator. The simulation results show that the designed algorithm can quickly calculate the path planning problem for minimum base disturbance, and the optimal trajectory of the manipulator is continuous and smooth. The attitude disturbance of the base decreases by 17.5% compared with the Resolved Acceleration Control (RAC) method. It effectively reduces the influence of the base attitude disturbance on the communication and observation of the ground in the process of target acquisition.Keywords：space free-floating robot;attitude disturbance;Gauss pseudospectral method;path planning- 50
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Published：2020-08-13 -
Design and modal analysis of space extendable and retractable mast(ERM)
Abstract：In order to meet the requirements of large spacecraft's flexible solar array in future for main bearing mechanisms with high reliability, high stiffness, repeated expansion/contraction and light weight, a kind of thin walled repeatedly Extendable and Retractable Mast (ERM) was designed, also the modal parameters of the ERM are analyzed. An nut and lead screw structure that allowed axial movement error was designed, which could perform the functions of high reliability extension and retraction conversion at any time, based on the principle of sliding spiral transmission. The influence coefficient of the connection stiffness between tubes is obtained through the prototype test, and then the finite element analysis model of ERM is modified, finally the modal fundamental frequency of the full expansion dimension is proved to be 0.3 Hz. The results show that ERM has better quality performance ratio than other deployable masts, and it is a preferred scheme for space station and large spacecraft.Keywords：flexible solar array;repeatable extendable and retractable mast;connection stiffness;prototype test- 43
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Published：2020-08-13 -
Design and experimental testing of a 9-DOF hyper-redundant robotic arm
Abstract：In order to perform on-orbit service tasks better, a spatial 9-DOF hyper-redundant robotic manipulator was designed. This manipulator could provide a large output torque, large reduction ratio and small joint length, with the characteristics of compact structure, high flexibility, space obstacle avoidance and etc. First, the design requirements of manipulator and main components of one joint were presented. Operating principle of the manipulator were analyzed by taking the driving method of two joints as an example. The torque was transferred via connecting shaft of output shaft. Then based on the method of backbone curve, the end-position coordinate of the manipulator was derived. Finally, the performance parameters of the manipulator were tested. The results show that the output torque of single joint can be up to 190 N·m and the angular velocity of single joint reaches 0.14 rad/s. The rotation angle error of the bottom joint of the 9-DOF manipulator is reduced within 0.1°. The proposed 9-DOF hyper-redundant robotic manipulator is reconfigurable and suitable for many different applications.Keywords：9-DOF;redundant manipulator;hyper-redundant;robotic arm;rotary joint;reconfigurable- 71
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Published：2020-08-13 -
Friction prediction of constant tension system based on T-S fuzzy model
Abstract：The friction seriously affects the accuracy and performance of constant tension suspension systems. In order to compensate the friction force, it is necessary to establish the model of the system and forecast the friction. Based on T-S fuzzy model, we use the method of fuzzy identification to obtain the model of the system, thus realizing the prediction of friction force. The optimal input variables of the model are selected by fuzzy search. An improved fuzzy c-means clustering algorithm is used to improve the efficiency of the system, and the method for selection of the clustering center number is added to the algorithm. The white noise signal is employed as input of the constant tension system model in simulations, and the output error of the obtained T-S fuzzy model is 0.013 5 N. In the slope, sine and other typical input signals, the model output is in the order of 1 000 N and the average error is approximately 0.01 N. The simulation results indicate that the proposed model which has high accuracy and low error is an effective method for friction prediction of constant tension systems.Keywords：constant tension system;friction prediction;T-S fuzzy model;fuzzy identification- 65
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Published：2020-08-13 -
Rigid-flexible coupling dynamics analysis based on deployable mechanism of LS-DYNA folding wing
Abstract：The deployment accuracy and stability of components of deployable mechanism for twice folding wing were influenced by dynamic behavior which includes rigid-flexible coupling phenomenon in the deploying process. In this paper, in order to determining the stress state of each component during deploying, the lift coefficient of the wing was obtained through CFD simulation by FLUENT software and the relationship between the aerodynamic load and time was determined based on the operating principle and structure features of deployable mechanism for twice folding wing. The rigid-flexible coupling finite element model was developed by HyperMesh software which simulated the stress and strain of components more effective than rigid model. By imposing aerodynamic load which was equalized on the wings, the deployable angle date of the middle wing and the maximum stress contours were obtained through the simulation. The simulation results show that the maximum stress of the link and the area on hinge joint up to 393 MPa and 189 MPa respectively. The design of deployable mechanism for twice folding wing meets the requirements, the link and the area on hinge joint were determined as the hazardous component which offers reference to the FMEA of deployable mechanism.Keywords：twice folding wing;aerodynamic load;rigid-flexible coupling;dynamic analysis- 78
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Published：2020-08-13 -
Design of deployable mechanism and accuracy measurement for heavy-caliber film camera
Abstract：Experimental research on system design of deployable mechanism and accuracy modeling for camera was conducted so as to realize application of heavy-caliber and high-precision spatial film imaging system with high stability to space exploration and earth observation. A systematic design scheme aiming at deployable mechanism of heavy-caliber and high-precision spatial film optics imaging was proposed based on spatial one-dimensional extended arm mechanism. Optical-mechanical structure of deployable film camera was constituted by extended arm of three articulated triangular trusses and primary mirror system of film supported by extended arm. Hinge joint of articulated triangular truss was driven by constant force spring so as to maintain rigidity through locking stop pin and strengthening tensioner after deployment. In consideration of dimension error of unit member for extended arm, hinge gap, and other factors, unit of extended arm was equivalent and precision analysis model was constructed, which was compared with test result of model machine. Deployable mechanism of heavy-caliber deployable film camera was completely designed with folding and deployable rate of 1:15. Unit of extended arm was subject to repetitive deployable accuracy measurement on the ground. Repetitive deployable accuracy in axis, vertical, and horizontal direction was respectively 24 μm, 261 μm, and 218 μm. It indicates that the extended arm has larger folding and deployable rate. Meanwhile, unit of extended arm has higher repetitive deployable accuracy.Keywords：spatial film camera;deployable mechanism;accuracy model;repetitive deployable accuracy measurement- 42
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Published：2020-08-13 -
Partition gelation casting in RB-SiC mirror billet
Abstract：A method for partition casting molding to realize mirror billet molding for SiC mirror was introduced in the Thesis; aimed at joining method and surface treatment for handover seam in partition casting area of mirror billet, one kind of scientific and reasonable technology scheme was proposed; Φ500 mm mirror billet was provided with research of partition casting molding by taking advantage of Gel-casting (Gel-casting) molding combined with reactive sintering SiC (RB-SiC) technology in the Thesis. The experiment result shows that this process is very feasible, and mirror billet strength after dry molding is relatively large; in case of SiC mirror billet obtained through 1 700℃ high-temperature sintering, whole contraction is consistent, and shrinkage factor is less than 1.2%. Density of mirror billet is not less than 3.0 g/㎝3, and it can be known form micro-structure analysis that:There are no interfaces between handover seam of mirror billet; preparing quality for mirror billet of SiC mirror conforms to requirements of spatial optical system design.Keywords：SiC mirror;partition gel-casting;mirror billet molding;manufacturing process- 53
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Published：2020-08-13 -
Design and stimulation of active disturbance rejection attitude controller of quadrotor
Abstract：Aimed at attitude control for quadrotor aircraft, active disturbance rejection controller (ADRC) was design and stimulation research was conducted in the thesis. Firstly, discrete model and actuator model of quadrotor attitude dynamics were established based on quaternion algebras. Next, basic composition of active disturbance rejection controller (ADRC) was introduced, and active disturbance rejection attitude controller subject to quaternion algebras as attitude description was designed. Finally, through mathematical simulation, performances of active disturbance rejection attitude controller and PID controller were compared. Stimulation result shows that under the condition of reaching the same response speed, control order output by active disturbance rejection attitude controller is smoother, and excellent control performance is shown under the condition of inputting order including noise. Active disturbance rejection controller based on quaternion algebras description can restore original input signal in noise, and quadrotor attitude control exceeds traditional PID controller in performance.Keywords：quadrotor;Active Disturbance Rejection Control (ADRC);controller design- 55
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Published：2020-08-13 -
Analysis for structural modal frequency of one rocket with two satellites of GEO satellite for full-electric thruster
Abstract：Changing chemical thruster platform to full-electric thruster platform can save satellite fuel, increase bearing ratio of satellite and prolong service life of satellite, and "one rocket with two satellites" launch can be adopted. Firstly, orbit transfer scheme at the time of using electric thruster was designed, with satellite launch weight of 2 700 kg, and parallel operation for two 300 mN thrusters was used. Transfer time from GTO to GEO was about 6 months, and consumption fuel of 650 kg was just needed. Aimed at current existing three kinds of launch modes for one rocket with two satellites, support, self-series and parallel inside rocket tank were provided with modal analysis by designing satellite configuration respectively to compare with previous chemical thruster scheme. It can be obtained that three kinds of configurations for one rocket with two satellites all meet requirements for rocket launch, of which support configuration inside rocket tank is the best with horizontal frequency of 20.781 Hz and structural weight ratio of 9.8% per satellite, and this configuration shall be used to conduct launch of one rocket with two satellites. Comprehensive analysis shows that adopting launch mode for one rocket with two satellites for support inside rocket tank of full-electric thruster is relatively good, which can save more than one hundred million of lunch cost, and its has excellent advancement and economy.Keywords：full-electric thruster;one rocket with two satellites;Modal analysis;structural weight ratio;economy- 40
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Published：2020-08-13 -
Virtual assembly and experimental technology of micro/nano-satellite
Abstract：In order to realize objective of rapid assembly and experiment for modal micro/nano-satellite, Virtual assembly and experimental technology were adopted. Modal design, rigging, experiment and condition and working condition of typical interface of micro-nano satellite were researched. Firstly, characteristic and technical process for Virtual assembly of micro/nano-satellite were provided with conclusion research, and rapid assembly system was developed and designed by taking advantage of 3D modeling software to realize quality characteristic analysis and intervention inspection of satellite modeling. Secondly, aimed at rapid construction concept of micro-nano satellite, all parts of satellite power/thermal model were provided with simplified database-creating according to standard module form, and model updating was completed. Finally, taking development for some micro-nano satellite as example, based on Patran/Nastran and AutoCAD/ThermalDesk software platforms, dynamic characteristic/heat balance characteristic and response of overall structure for satellite under actual experimental working condition and boundary condition were stimulated by adopting methods for local physical experiment and low-load physical experiment etc. on computer. It shows in research that Virtual assembly and experimental technology have important reference value to overall optimization design and condition formulation during the process of experiment of satellite. Through use of Virtual experiment technology, overall development period can be shortened by 30%-50%, and development cost can be lowered by about 30%, which can meet development requirements for "more", "rapid", "good" and "saving" of micro-nano satellite in our country.Keywords：modularization;Micro-nano satellite;virtual assembly;virtual experiment;finite element model updating- 65
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Published：2020-08-13 -
Recovery for sparse scene flow of spatial two-dimensional image and depth image
Abstract：Aimed at traditional scene flow, global energy function was utilized to calculate dense optical flow field, which caused large calculation amount and use for practical applications for failure to track in spatial target and 3D reconstruction etc., one calculation method for sparse scene flow combined with 2D image and depth image under LK framework was proposed in the Thesis. Firstly, supposing that plane optical flow of target is only just affected by translation motion, plane motion model for sparse optical flow was established on 2D plane; then, according to depth information provided by depth camera, combined with plane motion equation, optimization function was established on spatial 3D, and least square method was adopted to solve this optimization function to get sparse scene flow. Finally, methodology proposed in the Thesis was provided with numerical simulation verification. The result shows that sparse characteristic on target surface can be provided with effective scene recovery by taking advantage of algorithm in the Thesis. At the same time, when target surface characteristic is within 400, average time of this algorithm is less than 0.2 s; when target surface characteristic is less than 200, average time of the algorithm is within 0.1 s; when target surface characteristic is less than 50, average time of the algorithm is 0.05 s. The result shows that arithmetic speed of the algorithm is rapid which can meet demand of real-time operation.Keywords：sparse scene flow;depth image combination;LK framework;three-dimensional optimization function- 53
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Published：2020-08-13 -
Digital elevation model with large scale and high precision based on image of TH-01 mapping satellite
Abstract：Aimed at the issue that difficultly obtaining digital elevation model (DEM) with large scale and high precision, a method utilizing TH-01 Mapping Satellite image to make DEM with large scale and high precision was discussed in the thesis. RPC model refined algorithm based on a few ground control points was proposed, and positioning accuracy of TH-01 Mapping Satellite image was improved further; matching method combined with feature and overall relaxation was proposed, and high-precision matching for stereo image was realized; PRC model for TH-01 Mapping Satellite image after refinement and homonymy point data obtained by stereo matching were utilized to conduct forward intersection to obtain high-precision DEM data. Image data in some place in western Liaoning of northeast was provided with experiment in the thesis, and experiment result shows that coverage scope of DEM data generated by taking advantage of mono TH-01 Mapping Satellite image reaches 60 km×60 km; under the condition that there is no ground control point, elevation precision of generated DEM data is 5.12 m, meeting precision requirements of the topographic map on a scale of 1:50 000; under the condition that there are 3 ground control points, elevation precision for generated DEM data is 3.01 m, meeting precision requirements of the topographic map on a scale of 1:25 000.Keywords：TH-01 mapping satellite;rational polynomial coefficients model;digital elevation model- 55
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Published：2020-08-13 -
Pooling strategy for quality evaluation of full-reference model low illumination image
Abstract：In order to design method for image quality evaluation of full-reference model more suitable under condition of low illumination imaging, aimed at attention characteristic for human vision and distortion characteristic of low illumination imaging, pooling strategy for quality evaluation with low illumination image based on context-aware was proposed. Through different distortion types, main object and its context information in image were provided with weighting by adopting specific weight methods in different spaces, and obtained Weighting Graph was used for Local Quality Diagram for similarity measurement of pooling characteristic to obtain final quality score. The experimental result shows that method in the Thesis is more satisfying to human visual characteristic, and root-mean-square error reaches 0.623 1, with Pearson linear correlation coefficient reaching 0.885 7, Kendall rank correlation coefficient reaching 0.704 9, Spearman rank correlation coefficient reaching 0.885 6. Compared with other five mainstream methods, it has the optimal subjective visual consistence; at the same time, aimed at main distortion type of low illumination image, four kinds of objective evaluation indexes are superior to contrast method.Keywords：image quality assessment;feature similarity;pooling;low illumination- 32
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Published：2020-08-13 -
Autonomous task planning of formation imaging satellites based on improved genetic algorithm
Abstract：Autonomous task planning is an important method for imaging satellites to fast react to emergent observing missions, and to capture ground targets effectively. For the autonomous task planning problem of fast selecting targets in observation area for formation flying satellites, an improved genetic algorithm was put forward to fast obtain imaging sequence for every satellite. First, constraints of a satellite observing a target were analyzed, and observation time and expected lateral swing angles were clarified for each satellite and target. Then, ground target, imaging sequence and formation satellites were coded as gene, string and individual respectively. For fast forming original imaging sequence containing several important targets for each satellite, an original population generation method was developed based on time judgement of satellite continuous lateral swings. Selection, crossover and mutation were applied iteratively to optimize the original population, so that imaging sequences with current-optimal gain corresponding to evolution times were achieved. Finally, a simulation example containing 10 satellites in formation and 160 ground targets with 3 grades was provided. The results show that the improved genetic algorithm can generate imaging sequences for all satellites within 30 s. Contrast with simple genetic algorithm, imaging gain of proposed algorithm is improved by 40%, and the number of important targets is increased by 1.6 times. Thus, it can meet rapidity and high-gain requirements of engineering application.Keywords：autonomous task planning;formation imaging satellites;improved genetic algorithm;imaging sequence- 49
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Published：2020-08-13 -
Degradation estimation for output power of silicon solar array of low earth orbit satellite
Abstract：Aimed at degradation for output power of solar array for long-lived low earth orbit satellite, silicon solar array for satellite in sun-synchronous orbit near 10:00AM at the time of descending node place was selected as object. On the basis of analyzing satellite orbit parameter drifting for inclination, illumination angle and earth-sun distance etc. and temperature change in solar array, fitting model for output current of solar array was established, and normalization of illumination angle and earth-sun distance was conduced to estimate degradation for output power of solar array and to conduct detection combined with actual in-orbit data. The result shows that under condition of orbital exposure decrease and relatively large illumination angle, annual degradation factor for output power of silicon solar array is approximately -0.003 1, and annual degradation rate is approximately 0.31%, which is obviously lower than degradation under morning and light orbit; it is predicted that degradation for output power will be lower than 6% 18 years later in-orbit, which can meet energy demand of long-lived low earth orbit satellite. Result is applied in telemetry diagnostic aid, energy estimate and prediction, healthy state evaluation of device in long-term measurement and control and management for in-orbit satellite.Keywords：low earth orbit satellite;silicon solar array;degradation estimation;output power;telemetry- 68
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Published：2020-08-13 -
Construction of full physical stimulation platform for fast verification of satellite attitude control algorithm
Abstract：n order to realize ground-based verification of attitude control algorithm of satellite, designing one kind of full physical ground stimulation system supporting rapidity and high precision is vital. Taking oriented at fast verification for attitude control algorithm of satellite as target, full physical stimulation system subject to dumbbell-shape three-axis air-bearing as core was designed in the Thesis. Firstly, through researching research and development and current state of design of air-bearing table home and abroad, performance index for dumbbell-shape three-axis air-bearing with full physical stimulation of satellite was confirmed. Then, overall design of air-bearing table was conducted. Afterwards, on the basis, stimulation platform for attitude control system of spacecraft was established by taking advantage of component technology, and sensitive device and actuator of attitude were provided with type selection to design CMGS configuration etc. Finally, control performance for stimulation platform was verified through attitude maneuver law based on by hierarchical saturation PD control and group control law of CMG based on robust pseudo-inverse algorithm. Result of attitude maneuver simulation shows that 40° fast maneuver with multi-axis and large-angle of three-axis tables can be realized within 27 s, and attitude pointing and stability are superior to 0.05° and 0.005 (°)/s. This stimulation system can meet fast and accurate control of attitude under condition of multiple constraints.Keywords：full physical stimulation;dumbbell-shape three-axis air-bearing;control moment gyro;fast verification of attitude control algorithm- 66
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Published：2020-08-13
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