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A new method of long-distance ground-based validation for high-precision inter-satellite ranging system is proposed. A piece of optical fiber with a length of 100 km is used as the long-distance signal path. The drift of the optical fiber transmission delay is suppressed substantially by measuring the carrier phase and then feedback controlling the optical delay line. In this way，the total transmission delay of the optical path remains stable. The phase transfer relationship of the system and the main noise in the system are analyzed meanwhile the corresponding models are established in this paper. Simulation and system experiments are performed to demonstrate that the actual accuracy meets the requirements of the system which can be used in the long-distance validation of a high-precision ranging system. [ABSTRACT FROM AUTHOR]

Considering the distortion of point cloud data during the detection of high orbit instability target by linear array scanning Lidar, a method for co-rotating differential scanning is described in this paper. The method is not to rely on multiple sensors to recover the distorted point cloud information, and finally to measure the relative position and orientation of a target. It bases on the topological instantaneous invariance of the distorted point cloud information of a moving target. Firstly，in this method，the motion increment and instantaneous motion parameters of the target are obtained by registration of the distorted point cloud in the adjacent scanning time. Secondly，restore the real geometric position of the distorted scanning line point cloud so as to complete the three-dimensional reconstruction of the target. Then take the target 3D model as the initial pose datum, which is updated continuously by setting the increment frequency threshold. Finally, the relative pose of the target is obtained through superimposing the motion increment. Under the condition of missing the prior information of the non-cooperative target，this method，by only using a single load，not only realizes the reconstruction of the target 3D point cloud model, but also measures the relative pose of the spatial non cooperative target accurately and efficiently. [ABSTRACT FROM AUTHOR]

ased on the hexagon unit cell, the correlation matrices between the mechanical response fields of macro and micro structures are constructed, and an integrated macro/micro analysis method in composite cryogenic propellant tanks is established in this paper. With the commonly used engineering strength criteria capable of predicting the different damage modes, the matrix cracking in the composite laminate is predicted under the mechanical and temperature loads. Results show that the following criteria agree well with the test data under the mechanical loads, including the macroscopic Hashin criterion, modified macroscopic Tsai-Wu criterion, 〖JP+1〗microscopic maximum stress criterion and microscopic Hashin criterion. However, considering the mismatching of the thermo-mechanical properties between the constituent materials, the predicted results using the microscopic strength criteria have imparities compared with the results using the macroscopic strength criteria under the thermal loads. Based on the comparison and analysis of the predicted results of the matrix cracking under different loads, the integrated macro/micro analysis method is proposed by utilizing the microscopic maximum stress criterion. Moreover, this method considers the effect of the imparities in the thermo-mechanical properties between the constituent materials, and is an effective way for the matrix cracking prediction of the composite tanks. [ABSTRACT FROM AUTHOR]

The closed-loop optimal guidance problem of the multi-objective and multi-constrained autonomous rendezvous with angles-only navigation is investigated in this paper. Firstly, considering the observability and robustness requirements, the performance indexes of the multi-objective optimization of the angles-only navigation and rendezvous guidance are established. On this basis, the objective function of the multi-objective and multi-constrained optimal rendezvous problem, and the solution method of the optimal guidance problem based on convex optimization are presented. Secondly, the framework and solution of the closed-loop angles-only navigation and guidance are proposed according to the “coupling” relationship between the navigation and guidance. Finally, the effect of the observability on the navigation and guidance performance is analyzed by simulation, and the effectiveness of the proposed method is verified. [ABSTRACT FROM AUTHOR]

For the motion state and structure estimation of a non-cooperative space target, the motion parameters are coupled, which leads to the slow convergence problem in the dual extended Kalman filter (Dual EKF) algorithm. In this paper, based on the stereo vision model, a feature line observation model is introduced for decoupling of the translational and rotational motion. Then the triple extended Kalman filter (Tri-EKF) algorithm is proposed to sequentially estimate the rotational, translational motion and structural parameters of the target. Compared with the Dual EKF algorithm, the simulation and experimental results prove that the Tri-EKF has a faster convergence speed on motion estimation and smaller average estimation error given limited observations. [ABSTRACT FROM AUTHOR]

For the problem of the on-orbit identification of the moment of inertia for a spacecraft with flexible appendages during a large-angle maneuver, a concurrent recursive algorithm is proposed in this paper, which combines the estimation of the inertia parameters with the state estimation of the flexible appendages’ vibration modes. The algorithm is based on the nonlinear dynamic model of a spacecraft with flexible appendages during a large-angle maneuver. The extended Kalman filter is used to estimate the states of the flexible appendages’ vibration modes, and the least square method is used to estimate the parameters of the moment of inertia. Finally, the inertia parameters of the spacecraft are obtained by the concurrent recursive algorithm. In order to improve the efficiency of the algorithm, a recursive algorithm based on one-step least square method and multi-step extended Kalman filter is proposed. Simulation results show that the proposed algorithm not only improves the computational accuracy and efficiency, but also has the capability of anti-interference. [ABSTRACT FROM AUTHOR]

An optimal problem of orbit maneuver when multiple targets need to be visited in a described period of time is modeled and solved in this paper. Firstly, the problem description and modeling process considering multiple constraints and performance indexes can reduce the searching space and improve the efficiency. Then focusing on the drawbacks of the classical differential evolution algorithm, an improved algorithm is proposed and applied on the multiple visiting target problem. The traditional algorithm is improved by designing the double self-adaption control parameters and introducing a random mutant to improve the efficiency of optimizing and make the algorithm can jump out when trapped into the local optimum. Specific simulation verifies that the SA-DE-RM (rand) algorithm has a better performance on average value, best result and mean square error and it is feasible and effective. [ABSTRACT FROM AUTHOR]

To visualize the detection area of the satellite scientifically, a virtual Celestial Sphere that can be rasterized for visualization is needed. Then a subdividing-mapping method is proposed in this paper. In the method, Graticules and HEALPix are used to subdivide and encode the Celestial Sphere, based on which the coverage area can be visualized according to the encoding number by projecting the texture to the 2D Celestial Sphere coordinate. Meanwhile, the method can adaptively generate the different texture images of the different sizes to fit the different subdivision levels without adding extra vertexes while the grade of the subdivision level rises, which can meet the real-time requirement in space science missions. Lastly, the proposed method is checked with the simulating data of the HXMT satellite and the real data of the DAMPE satellite launched in December 2015. [ABSTRACT FROM AUTHOR]

In order to be implemented for real-time execution and use color information, an improved scale-invariant feature transform (SIFT) algorithm based on the contrast enhancement and DAISY descriptor is proposed in this paper. The color offset and the exposure offset of the pixel are calculated from the color image and the original grayscale image. The two offsets are added to the gray level to gain the contrast enhancing image according to which the SIFT feature points and the main directions are got. The DAISY descriptor of the feature point is obtained from the partial derivative values of the feature point and the sampling points with different directions. To evaluate the accuracy of the algorithm under different view changes, the feature points extracted from the standard image data sets are matched by the K-nearest neighbor (KNN) algorithm. The experimental results show that the algorithm can obtain more feature points. Furthermore, it guarantees the accuracy while reducing the time of the descriptor generating process and the feature matching process. [ABSTRACT FROM AUTHOR]

A linear estended state observer (LESO)-based dynamic surface controller is proposed in this paper for the cruising control problem of a hypersonic flight vehicle (HFV) with model parametric uncertainties and external disturbances. First of all, the longitudinal model of the HFV is denoted, and the decoupling of the altitude and velocity is realized via the nonlinear dynamic inversion (NDI) technique. Then, combining with the conventional back-stepping technique, a tracking differentiator based on the inverse hyperbolic sine function (IHSTD) is adopted to attain the derivatives of the virtual control laws, which avoids the problem of "differentiation explosion". And then a LESO is designed for the precise estimation and compensation of the "lumped disturbance" containing parametric uncertainties and external disturbances, which tremendously improves the ability of the disturbance rejection of the system. Finally, the stability of the proposed approach is analyzed by means of the Lyapunov stability theory. The exploited approach guarantees the asymptotic stability and robustness of the system, and the simulation results demonstrate the validity of the proposed method. [ABSTRACT FROM AUTHOR]

A constrained robust attitude control algorithm is addressed for a hypersonic vehicle with angle of attack constraint, input nonlinearities and uncertainties in this paper. First, the angle of attack constraint issue is properly handled by the integral barrier Lyapunov functions (IBLF) method integrating with the dynamic surface control technique. Moreover, the angle of attack is guaranteed in its constrained set while the "explosion of complexity" is properly avoided. Then, to eliminate the effectiveness of the actuator nonlinearities, a novel auxiliary error compensation design is employed based on the compensated tracking error. In addition, the uncertainties are estimated and compensated by utilizing the nonlinear disturbance observer. Finally, the uniform ultimately boundedness of the closed-loop control system is rigorously ensured by the Lyapunov theorems. The numerical simulation results demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

A low-complexity prescribed performance control (LCPPC) method on basis of the prescribed performance control theory is proposed in this paper for a chasing spacecraft approaching and tracking a non-cooperative target spacecraft. Any information of the system parameters, including the mass and inertia matrix of the chasing and target spacecraft, is unnecessary. Moreover, the transient performance as well as the steady performance of the system can be prescribed and guaranteed despite the external disturbance, parameter uncertainties and unknown non-cooperative target's maneuver. The simulation results show that the high precision real-time control is realized for approaching and tracking the non-cooperative target in a line-of-sight coordinate system. [ABSTRACT FROM AUTHOR]

Based on the visual camera, a robust and efficient method for tracking and predicting the trajectory of a space spinning target is proposed in this paper. The initial discrete point set of a motion trajectory is firstly accumulated in real-time, and then the motion is decomposed into translation and rotation. A hybrid extended finite impulse response (EFIR)/discrete Fourier transform (DFT) is used to estimate the states and dynamics parameters in time domain and frequency domain simultaneously. According to the dynamic equations of a free-floating object, we achieve the long-term and precise prediction while the measurement noise and process noise are unknown. The experiment with ground robot is presented to verify the correctness and effectiveness of the proposed method. The results show that the trajectory of a space spinning target can be predicted accurately using our proposed method. Comparing with the traditional extended Kalman filtering algorithm, the presented control method can improve the the speed of the parameter estimation and the accuracy of the trajectory prediction despite the noise covariance and the initial conditions are not exactly known in advance. [ABSTRACT FROM AUTHOR]

Owing to the large deformation, noncontinuity and contact/impact, the simulation for the deployment of the large scaled solar arrays is faced with great numerical difficulty. In this paper, based on the co-rotational formulation and the plate/shell theory without rotation, a multibody dynamic model of a flexible solar array is established by considering the geometrically nonlinear effect of flexible battery cell and the contact/impact between the battery plates. Then the numerical simulation of the deployment process of the large solar cell array is carried out, and the complex dynamic phenomena in the development process are analyzed. The results given by this study show the features of the response, the stress distribution and the regular pattern of the contact between the base plates. This work can be referred to design and optimize the large scaled solar arrays in the space station, and it can be easily extended to the simulation for other large scaled space structures. [ABSTRACT FROM AUTHOR]

Material series of baffle have achieved an essential change, and high performance fiber reinforced resin composites have become basic materials with the fast development of space remoter sensor system. On the whole, engineering application is still at starting phase of substituting traditional materials by composites to meet product requirements. In this paper, application tendency of high performance fiber reinforced resin composites in baffle is analyzed. Then the problems to be resolved about engineering application are briefly summarized. Aiming at different types of remote sensor baffles, for example, honeycomb sandwich structure, aperture structure and son, composite materials and their forming processes are introduced in this paper. The key techniques of engineering application such as material selection, manufacturability and process design are preliminarily discussed. The practical effects of high performance fiber reinforced resin composites of baffle are also evaluated. Finally, demands for advanced materials and techniques for developing space remote sensor system are forecast. [ABSTRACT FROM AUTHOR]

Joint torque control system plays a key role in the space manipulator assisted docking mission for a spacecraft. A detailed joint dynamics model including joint clearance, non-linear stiffness and joint damp, is established in this paper. Both Gear meshing stiffness and gear axle torsional stiffness are considered in the non-linear stiffness. A new method for measuring the joint torque is proposed, then, a joint torque control system is established in this paper, and the equations are solved numerically by using Runge-Kutta method. The results show that the joint torque control system is effective. The new method for measuring the joint torque can solve the conflict between the measurement accuracy and the [ABSTRACT FROM AUTHOR]

From an attitude control point of view, spacecrafts with moving flexible appendages are much more complex than those with fixed ones. Focusing on this sort of complex spacecraft, the attitude dynamics model is discussed and analyzed briefly in this paper, and then the uniform bounded stability of the output-feedback-based PD control system is proved theoretically. In order to guarantee the asymptotic stability of the system, an internal model-based control system is constructed, and then the stability proof is given based on Lyapunov theory. With the model parameters published by the American geostationary meteorological satellite GOES-8, the two kinds of controllers are simulated and compared with each other. This paper draws the concluding remarks and proposes a possible research topic in the end. [ABSTRACT FROM AUTHOR]

A novel two-dimensional error codes correction circuit which can effectively mitigate radiation-induced MBU in memory is proposed in this paper. The key features of the proposed method are that it can correct MBU with any possible width and assure the reliability of memory with very low cost overhead. Firstly, the proposed two-dimensional error codes are constructed in the paper. A word in memory is transformed to a matrix form. Low complexity multibit error detection codes are applied in each row for error detection while parity codes are applied in each column for error correction. Then, the correction algorithm of memory against MBU is proposed in the paper. Finally, the circuit and its layout design of the proposed method are implemented. A method called layout partition is proposed to mitigate MBU in the redundancy bits of the two-dimensional error correction code to further improve the reliability of memory. The experimental results reveal that the proposed method has a higher reliability. Compared with the existing muhibit error correction codes, it has lower encoding and decoding overheads, even for Hamming codes. [ABSTRACT FROM AUTHOR]

In this paper, a Taylor-series location method and its performance analysis are presented in presence of sensor position errors for general measurement equations. Two cases in the absence of calibration sources (a) and in the presence of calibration sources (b) are discussed. For the case (a), two Taylor-series iteration formulas are given, and their theoretical performances are proven to be consistent with each other, and equal to the corresponding Cramér-Rao bound (CRB). For the case (b), the Taylor-series location formula based on the difference calibration (DC) location is derived. Aiming to the shortcoming of the DC location technique, the Taylor-series iterative method based on two-step optimal fusion is proposed, whose theoretical performance is proven to reach to the corresponding CRB. Finally, some simulation experiments for two passive location scenarios are conducted to verify the effectiveness of the location algorithms and the performance analysis in this paper. [ABSTRACT FROM AUTHOR]

In this paper, the development of end-effector for space station is surveyed, and function, technical specification and suitability are analyzed. Second, the structures, principles and characteristics of latching end-effectors are introduced. Finally, based on the research of the end-effector in China, the key techniques ate pointed out for the end-effector development. The research in this paper is beneficial to the space station construction of China. [ABSTRACT FROM AUTHOR]

A frequency estimation algorithm for the deep space telemetry, tracking and control (TT&C) system under low Carrier-Noise-Ratio (CNR) and high dynamic conditions is presented in this paper. Considering the drawbacks of the exist algorithms, an advanced closed loop carrier tracking algorithm based on the unscented Kalman filter (UKF) is proposed. This new algorithm combines the advantages of the discriminator of the frequency lock loop and UKF to obtain a wide estimation range, high estimation accuracy and low CNR threshold. In addition, it is found on the basis of the analysis of the two kinds of models that this new algorithm cost much less computational effort than the conventional UKF. The high dynamic trace of receiver is simulated in this paper. The results show that the proposed loop structure can apparently improve dynamic capability, convergence performance and tracking accuracy, thus effectively completing the task of frequency estimation under low CNR and high dynamic conditions. Compared with the frequency estimation algorithm based on extended Kalman filter (EKF), this new algorithm has a much smaller frequency estimation error so that it will have prospective application potential. [ABSTRACT FROM AUTHOR]

In order to improve the hot environment that faces missiles launched by concentric canister launcher(CCL) , the factors that affect the gas temperature at the outlet of CCL are discussed and the fundamental gasdynamics principle in the process of reducing gas temperature are also analyzed in this paper. And several research works for reducing outlet gas temperature of CCL are analyzed with the energy conservation theory in the paper, several kinds of CCL developed by others are explained in detail about how to reduce gas temperature at the outlet of CCL. Furthermore, a new type, variable cross-section concentric canister launcher, is proposed in the paper. The gap between outer and inter canisters of the launcher is designed to be a convergent-divergent shape similar to the Laval nozzle to enhance the outlet velocity of gas while reduce its temperature. FLUENT software is used to numerically simulate a 2-D convergant-divergent type CCL. The simulation results show that the convergant-divergent type CCL can improve the missiles faced hot environment. [ABSTRACT FROM AUTHOR]

The Mosaic mode is a hybrid mode of spotlight and ScanSAR, and it can image a large coverage at a high resolution. In the paper, an easily realized Mosaic mode is proposed. In the mode, the beam switching in range is realized by electrical beam steering, whereas the beam steering in azimuth is realized by mechanical beam steering. The agile satellite can realize the mechanical beam steering by pitching maneuver expediently. Thus, it is fit for the implementation of the Mosaic mode. In this paper, a new system design method is presented for the Mosaic mode. Beginning with the broadside position, the nonlinear system in the unknown squint angle and dwell time of the burst is iteratively solved. In this way, the system parameters and timeline of the Mosaic mode are obtained. Moreover, a new approximate computation method tor the performance parameters is obtained based on the equivalent stretch of the azimuth antenna pattern. It can achieve the performance parameters of the Mosaic mode visually and expediently. [ABSTRACT FROM AUTHOR]

In this paper, an adaptive eovariance matrix estimation algorithm based-on BP neural network learning is proposed to solve the window size selection problem in Sage-Husa adaptive filtering way. The innovation vector derived from the Kalman filter (KF) is employed as the input to the BP neural network and the nonlinear function between the innovation vector and the innovation covariance matrix can be determined through learning of the network. The covarianee matrix estimation algorithm proposed in this paper is applied to the autonomous orbit determination system. The simulation results show that the mean constellation URE of autonomous orbit determination will be within 1.9 meters in 60 days and it has better performance than the Sage-Husa adaptive filtering in the estimation of the system covarianee matrix of the autonomous orbit determination algorithm. [ABSTRACT FROM AUTHOR]

Because the boundary layer of the plasma sheath formed around the hypersonic vehicle flying in atmosphere is turbulent, the parameters of plasma sheath such as the electron density and so on become time-varying. The effects of electron density fluctuations on electromagnetic wave propagation are focused in this paper. Both amplitude and phase of EM signal are modulated by the time-varying plasma, and the modulation has much to do with the carrier wave frequency and the plasma parameter. The EM signal propagation through the time-varying plasma is simulated under different conditions in this paper, and the propagation of QPSK signals is simulated, when carrier wave frequency is 35GHz and 12GHz. The simulation results demonstrate that the modulation will make the constellation of the QPSK signals circumvolving, and the modulation is weakened when the carrier wave frequency is much higher than the plasma frequency. [ABSTRACT FROM AUTHOR]

The model of differential phase delay of same beam interferometry (SBI) is analyzed according to the requirement for the high accuracy ground based guidance and navigation of the lunar orbit rendezvous and docking mission. The differential phase delay measurement model of same beam interferometry is propagated based on the same wave front definition of very long baseline interferometry (VLBI). An accurate differential phase delay closure algorithm of same beam interferometry is derived based on the definition of the same wave front of SBI and the geometry delay closure algorithm of VLBI. The value of differential phase delay closure is calculated by using the observation data of the SELENE mission of Japan, and the result shows that the accuracy of differential phase delay closure is in the range of 0.5 ~ 1ps. The algorithm given in the paper could evidently reduce tends of differential phase delay closure, and the validity of the measurement model is verified in this paper. It is of some significance for high accuracy ground-based navigation of the forthcoming lunar orbit rendezvous and docking mission. [ABSTRACT FROM AUTHOR]

In order to improve the quality of the signal obtained by analog Dechirp method and reduce the computation load of matched filtering after direct IF (Intermediate frequency) sampling, a digital Dechirp method combing the benefits of these two methods is proposed in this paper. By theoretical analysis, the mathematical model is obtained, and the data decimation and the filter design are also analyzed in detail for the realization of method provided in this paper. Compensation approach for the system distortion is also proposed. Simulation and analysis based on measured data prove the effectiveness and efficiency of the proposed strategy. [ABSTRACT FROM AUTHOR]

A rapid attitude tracking-based navigation strategy for non-cooperative target tracking is proposed in this paper. In order to cope with the output interruptions of the laser range finder, the relative position-velocity based filter with variance correction is used for approximate tracking; when the laser range finder works properly, the navigation filter based on full-dimensional state observer is adopted by introducing the pole-assignment method and indirect measurement matrix, and the convergence rate can be regulated by using different pole-assignments. Series of simulations are performed with different initial conditions to demonstrate the filter behaviors. The result shows that the navigation strategy proposed in this paper can be used to cope with the interruptions of the laser range finder effectively, and compared with the traditional Extend-Kalman filter, the computational complexity due to matrix derivations can be avoided, and the convergence rate of the navigation filter is improved consequently. [ABSTRACT FROM AUTHOR]

In order to satisfy the lightweight requirements of satellite structure, a structural design process which combines the advantage of the topology optimization method in structural design and the advantage of the additive manufacturing in structural manufacture is proposed in this paper. Firstly, the best load path is found in the feasible design space using the topology optimization method with the additive manufacturing constraints in mind. Secondly, a trussed structure is extracted from the optimized results and the crosssectional dimension of the truss is optimized using the sizing optimization method. Finally, after rebuilding the structure based on the previous analysis results and some essential geometry features, a new additive manufacturing oriented design is obtained. Applying the proposed method to a sensor bracket of a satellite, a lightweight design whose mass is reduced by about 35.4% relative to the original design is achieved. With the same material parameters and load cases as the original design, the detailed mechanical analysis shows that the new design improves the fundamental frequency by 34.3%, increases the margin of safety by 13.0%, and reduces the dynamic response coefficient by 7.3%. The test case verifies the feasibility of the proposed method in structural design and a helpful reference is provided for the lightweight design of the similar structure. [ABSTRACT FROM AUTHOR]

In a strapdown attitude updating algorithm, a general numerical method for obtaining the multi-sample noncommutativity error compensation coefficients is presented. Under the condition of the angular motion expressed as polynomial, the linear relationships between the angular velocity polynomial, angular increment polynomial and multi-sample angular increments are established in this paper. According to the vector cross product operation of the noncommutativity error polynomial in the equivalent rotation vector differential equation, the cross product is converted into the convolution operation of the polynomial coefficients. Then, the numerical methods to compute the noncommutativity error compensation coefficients of the arbitrary multiple samples are presented in deduction, which are easy to be implemented with computer programming. Finally, simulations are carried out to obtain the 2~6-sample compensation coefficients, in which the 2~4-sample coefficients are consistent with the existing literatures and the 5 or 6-sample coefficients are firstly proposed by the authors. [ABSTRACT FROM AUTHOR]

In order to realize remote and high precision kinetic energy interception, a closed-loop mid-course guidance law based on general energy management (GEM) is designed to solve the problem of the exhaustion shut down of an interceptor with solid fuel engine under strong time constraints. In this paper, the impact of the non-spherical J2 perturbation on the trajectory is firstly considered to improve the algorithm of the Lambert problem and correct the deviation of the demand velocity caused by the Earth oblateness perturbation in the long-range interception, elevating the demand velocity accuracy by an order of magnitude. Then, an energy modulation angle virtual mapping relationship is presented based on the GEM to achieve the attitude command smooth transition during the energy modulation initial stage. And the near-off point thrust direction strategy is changed to solve the command divergence problem. The introduction of the accelerometer feedback in the guidance process enhances the robustness to the propulsion system parameters. Six-degree-of-freedom simulation shows that this guidance law is more accurate and adaptable than the conventional GEM guidance law. [ABSTRACT FROM AUTHOR]

For a spacecraft with high thrust, a general equations based on variational calculus for formulating the Hamilton boundary value problem (HBVP) is proposed, where the optimality conditions on interior points and other general boundary points (inclucling initial and final points) are in the same manners, so that our equations tend to reveal the more intrinsic analytic structure of HBVP. The detailed optimality conditions can be determined conveniently according to the general equations; therefore, the tedious task of formulating HBVP is precluded. Simulations show that the method proposed in this paper could ensure obtaining the optimal flight path of the high-thrust spacecraft effectively and efficiently. [ABSTRACT FROM AUTHOR]

In order to meet the development requirement of spacecraft onorbit service system technology, a dynamic trajectory planning method of a space manipulator for capturing a tumbling target is proposed in this paper. Firstly, on the basis of the system assumptions, the dynamics model and the velocity gain matrix of the space manipulator for capturing a target are derived. Then, the dynamic regulation method of the velocity gain matrix is presented. Furthermore, the dynamic trajectory planning method of the space manipulator is developed in detail. Finally, the effectiveness of the method is verified by a numerical simulation performed with MATLAB and ADAMS. The results illustrate that the proposed method can not only reduce the capturing time but also prevent the excessive starting and residual velocities, as well as avoiding the singularity of the Jacobian matrix. The method is practical in engineering for a space manipulator to capture a tumbling target. [ABSTRACT FROM AUTHOR]

In view of the current situation that the deep space stations are few in Chinese Deep Space Network (CDSN), the long time tracking and the need of high precision of spacecraft relative positioning, a method based on the phase reference imaging technique for the relative position determination between deep space probes using a single baseline is proposed in this paper. This method takes advantage of the improved UV coverage generated by the long observation intervals of the CDSN in deep space missions, and can achieve a high-accuracy angular separation determination with just a single baseline. Experiments with the Chang'e-3 lander have been conducted using the two available deep space stations, Jiamusi and Kashi, to verify the validity of the new method. The relative angular position between the high gain antenna and the low gain antenna of the lander has been determined with an accuracy better than 0.5 mas, indicating it's possible to acquire the high-accuracy VLBI measurements with just a single baseline. This study may provide good references for the radio interferometry in future deep space explorations. [ABSTRACT FROM AUTHOR]

Aiming at on-orbit servicing fine operation, the dimension chain errors of a space manipulator system are analyzed in this paper. A calibration strategy based on the manipulator off-line planning trajectory compensated with the hand-eye camera measurements is proposed to correct the position and pose errors caused by the zero-gravity and on-orbit assembly of the manipulator and orbital replacable unit (ORU). Ground tests by setting the deviation position and pose conditions of an ORU are designed and completed. Finally, the results of the orbital experiments are presented to verify the effectiveness of the proposed methodology. China′s first space manipulator system on-orbit servicing fine operation has been tested successfully. [ABSTRACT FROM AUTHOR]

In view of the problems of slow convergence and sensitivity to initial conditions in the traditional continuous self-calibration of an inertial platform because of the nonlinearity of the system and the large number of dimensions of the state vector, the dual extended Kalman filter is researched in this paper. Firstly, the error models of the continuous self-calibration are given. Then the output error of the accelerometer is pre-filtered according to the relationship between the accelerometer error and the navigation velocity error. At the same time, the gyro error is decoupled from the output error of the accelerometer by analyzing its propagation characteristics in the continuous self-calibration. At last, the dual extended Kalman filter is carried out by using the gyro error and the accelerometer output as the observations respectively to establish the filter equations of the gyro and the accelerometer, which can reduce the nonlinearity of the system and the number of the dimensions of the state vector. Simulation results indicate that the continuous self-calibration method based on the dual extended Kalman filter can calibrate all the error coefficients of the inertial platform with relative error lower than 0.05% within 900s and is not sensitive to the initial conditions, which is beneficial to the application of the continuous self-calibration of the inertial platform. [ABSTRACT FROM AUTHOR]

A constraint satisfaction model and a discrete differential evolution combined with variable neighborhood search (DDE-VNS) are proposed in this paper for an agile satellite task scheduling considering the influence of the observation time on the imaging quality. Firstly, the temporal constraint of the agile satellite task scheduling is described. Secondly, considering the influence of the observation time on the imaging quality, the constraint of the attitude transition between tasks, and onboard storage and energy, the constraint satisfaction model of the agile satellite task scheduling is established. Thirdly, the mutation, crossover and selection operators of the discrete differential evolution are designed, the variable neighborhood search is adopted to exploit better solution from the optimal solution at each iteration, and also the workflow of the proposed algorithm is described. Simulations have demonstrated that the model and algorithm proposed can get schedule plans with cracking reward and quick converge. [ABSTRACT FROM AUTHOR]

In this paper, the aerodynamic characteristics and control strategy design method of the HTV-2 like vehicle are studied when the lateral control deviation parameter (LCDP) is greater than 0. Considering the characteristics of the HTV-2 space vehicle lateral static stability easy to obtain, the design method of the aerodynamic characteristics and control strategy is proposed by using the lateral/directional channel coupling. The analysis shows that the method can be used to design the aerodynamic characteristics and the control strategy to realize the stability of the system with LCDP greater than 0. [ABSTRACT FROM AUTHOR]

A new free-interface component modal synthesis (CMS) method is developed in this paper based on the Kron's substructuring. For better precision, the inertia approximation of the residual attachment modes, which depends on the unknown global eigenvalues by definition, is included in the modal transformation matrix while the reduced system eigen-equation is still linear. Moreover, the generalized coordinates are further condensed to reduce the size of the reduced model. Compared with the conventional static-approximated CMS methods, the precision is significantly improved with little additional computational cost. Numerical examples validate the precision and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

Based on the review of planetary drilling and coring technologies, this paper elaborates the mechanical properties of planetary regolith and the preparation method of the soil simulant. Then, the experimental and theoretical drilling and coring characteristics are analyzed respectively. Meanwhile, the self-adaptive drilling strategy containing the drilling states recognition and autonomous drilling control are carefully researched. Based on the above foundations, the technical prospects and advices have been proposed for China lunar exploration. [ABSTRACT FROM AUTHOR]

This paper studies the charging/discharging effect of the high-voltage solar arrays of the Chinese space station in the low Earth orbit plasma environment experimentally, and the electrostatic discharge and secondary discharge have been measured in the lab. The results indicate that the biased-voltage of the solar arrays electrostatic discharge is -70 V. The electrostatic discharge of the high-voltage solar arrays is observed to be more frequent when the biased-voltage decreases, and it easily occurs when the solar arrays in a higher density plasma environment. The secondary discharge has been measured when the biased-voltage is -100 V and the string-voltage is 80 V. [ABSTRACT FROM AUTHOR]

To solve the problems of possible real-time trajectory correcting and landing site re-designating during Mars powered descent, the paper computes the reachability set at the beginning of the powered descent phase offline and determines the final landing site online by comparing the current state of the lander with the obtained reachability set. The corresponding descent trajectory is then rapidly searched. If the lander fails to reach any of the given targets, a new landing site in the field of view will be selected through safety index and a trajectory will be planned. The simulation result shows that the proposed reachability set-based rapid trajectory planning method manages to determine the final landing site and obtain the landing trajectory in real-time according to the practical initial state of the lander, fulfilling the goal of Mars soft landing with limited fuel consumption. [ABSTRACT FROM AUTHOR]

In order to absorb the vibration from the flywheel, a nonlinear energy sink ( NES) is presented in this paper. The NES is composed of a linear spring and the parallel Euler buckled beams. A discrete multi-degree-of-freedom dynamic model, including the flywheel, the NES and the supporting structure is built. The systematic dynamic equations under the transient and steady loadings, respectively, are solved by fourth-order Runge-Kutta method. Based on these calculating results, it is shown that the NES exhibits the efficiency of energy transfer from the linear system, which includes the supporting structure and the flywheel, to the NES. Meanwhile, the targeted energy transfer has been excited. Then, a detailed computational research of the different types of nonlinear energy transitions that occur under the three-level inputting energy is provided. As a result of these studies, the medium-level exciting energy leads to the effective targeted energy transfer from the linear system to the NES. Under this condition, it exhibits that apparent responses of the NES in a wider frequency range. According to the calculating results under the experimental data from the flywheel, it can be concluded that the NES has suppressed the influences from the disturbance of the flywheel effectively. [ABSTRACT FROM AUTHOR]

A method on the inverse kinematics of variable geometry truss (VGT) is proposed in this paper for the assembling of the space station modules. This method is based on an equivalent manipulator model and the diffusion process of the workspace density function. Firstly transfer each order of the VGT into the equivalent manipulator model and calculate its workspace density function. In the base module frame, every workspace density function is the diffusion process of all its preceding ones. Then a group of manipulator variables could be got by searching for those maximizing the workspace density function value at the desire position. The variable links of the VGT could be calculated by transferring the manipulator variables back. This method has a higher efficiency than the b ru te searching. The numerical simulations have demonstrated the effectiveness of the approach proposed. [ABSTRACT FROM AUTHOR]

Focusing on the key dynamic problems of a Mars probe in the entry, descent and landing (EDL) stages, the detailed dynamic models including the entry of the probe, the deployment, inflation, and steady descent for the parachute are built. The dynamic characteristics of the Mars entry trajectory are analyzed based on the 6-DOF model, the initial simulation conditions of the parachute deceleration are achieved by the ascendant adaptive opening control method, and the dynamic characteristics of the parachute's deceleration are investigated by the empirical models of the parachute's deployment and inflation and the 9-DOF multi-body model of the parachute-body. Finally, an integration simulation framework of the EDL is established based on the object oriented design language, achieving parametric modeling of the EDL whole process from the Mars entry point to landing point. The results of this paper could be applied to effectively predict the dynamics of the Mars EDL process, and guide the integration design analysis of a Mars landing system. [ABSTRACT FROM AUTHOR]

An algorithm based on discrete particle swarm optimization (DPSO) is proposed in this paper for the optimal test-sequencing for the fault detection of a launch vehicle. This algorithm optimizes the original test set first to obtain the optimal test set, and then optimizes the test sequence based on the optimal test set. A timing sequencing control system is taken as an example for modeling. The result shows that this algorithm not only reduces the quantity of the test sets and the test cost, but also performs much better than the genetic algorithm (GA) in the optimization results and computational efficiency. [ABSTRACT FROM AUTHOR]

Aiming at the problem that the traditional algorithm cannot detect the near space hypersonic target effectively, a kind of track-before-detect (TBD) algorithm based on Hough transform and multi-constraint conditions is proposed. Firstly, to get the potential target tracks, the time-radial distance measurement data is used for Hough transform, and the parameter space variable θ is made as the accumulation constraint condition to avoid invalid accumulation. Then, all potential tracks are dealt with velocity constraint and angle constraint to further eliminate false tracks and clutter points inside the track. Finally, after merging the same target tracks, the final confirmation tracks are obtained. The validity of the algorithm is verified by simulation, and the algorithm performance under different SNR and clutter density is analyzed. The simulation results show that the near space hypersonic target under the clutter background can be effectively detected according to the algorithm in this paper. [ABSTRACT FROM AUTHOR]

To deal with the high accuracy requirements of peg-in-hole assembly task performed by the robonaut, a hybrid force/position control method considered coordinated operations is proposed. The dynamic model of the robonaut including the coupled trunk is established at first. Then, the motion constraint relationship between two manipulators is presented to design the hybrid force/position control method of the robonaut considered coordinated operations. A MATLAB simulation of the robonaut performing peg-in-hole assembly task verifies the correctness and effectiveness of the proposed method. The results show that the relative position and orientation and the interaction force between peg and hole can be control accurately by using the method proposed in this paper. Comparing with the traditional hybrid force/position control method which does not consider coordinated operations, the presented control method can reduce operation time while improving control accuracy. [ABSTRACT FROM AUTHOR]

Current methods of the periodic orbit computation have the disadvantages of requiring large amount of computation, varying the Jacobi energy, and the limitation to calculate the specific periodic orbits, a novel method of the periodic orbit computation is proposed in this paper. Firstly, a modified Poincaré section map is created, on which the projection points from every initial point are plotted and the evolution and fork of the periodic orbits by the initial point could be intuitively reflected. Secondly, based on the modified Poincare section map, the candidate interval of the periodic orbits are selected by the relationship between the initial points and the projection points. Thirdly, the initial guesses are generated which are quite close to the true solution in the candidate interval computation using the state transition matrix. Finally, the periodic orbits can be rapidly computed numerically by a single shooting method. The proposed method does not need to change the Jacobi energy, requires less iterations for a given value of the Jacobi energy, and enables a large set of periodic orbits with x-axis symmetry. Examples are presented in the Earth-Moon Circular Restricted Three-Body Problem to verify the efficiency and rapidity of this method. [ABSTRACT FROM AUTHOR]

As the fixed-trim reentry warhead only has a single axis of rolling control, a novel terminal guidance law with impact angle constraint is proposed in this paper. The three-dimensional terminal guidance law combines the traditional circular navigation guidance approach with impact angle constraint and the improved cross-product guidance method without impact angle constraint for fixed-trim warheads. According to the theoretical analysis, it has been proved that the new guidance law will guarantee zero miss distance and impact angle constraint by choosing proper guidance parameters. For improving the robustness of the guidance law, a linear disturbance observer is combined with the variable structure control to estimate the system uncertainties and disturbances during flight. Simulation results show that the proposed terminal guidance law can satisfy both miss distance requirement and impact angle constraint perfectly. [ABSTRACT FROM AUTHOR]