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The rigid-flexible coupling dynamics model of a separated satellite with flexible cable is derived using Lagrange method. Based on the proposed model，the flexible cable effect on the vibration isolation performance and pointing control of the satellite is investigated. The simulation result indicates that the flexible cable decreases the vibration isolation performance at low frequencies. Furthermore ' the low frequency disturbances from the support module dramatically degrade the attitude accuracy and stability of the satellite. The flexible cable also has significant effect on the pointing control performance of the payload module. Using the same PD controller, the steady-state error of the payload module with flexible cable is 4 orders of magnitude larger than that of the payload module without flexible cable. It can be concluded that the performance of the payload module is seriously degraded by the flexible cable. The dynamics model in this paper is important on how to improve the modeling and control accuracy of the separated satellites. [ABSTRACT FROM AUTHOR]

The movement space of the LIDM's capture system is studied in this paper. The main factors affecting the movement space including the arm length of actuator, the rotation angle of revolute pair, the inner diameter of structural frame, and so on are proposed. The movement space of the capture system and its cross-sections are analyzed, and the influence of the framework's internal diameter on the movement space is discussed in detail. The study is significant for designing and optimizing the LIDM. [ABSTRACT FROM AUTHOR]

Considering the limited resource, complex constraint and parallel activities, autonomous planning of spacecraft mission is investigated in this paper. A method for calculating the spacecraft resource based on the temporal topological sort is proposed. In consideration of resource production and consumption in the planning result, a resource constraint network model is introduced to express resource requirement for each activity. According to the analysis of the relations between resource changes and activity executing time, the resource mutation time of the resource constraint network is topologically sorted in the resource processing. The selection process of flow pushing path is optimized, and the time complexity is O(n²). Finally, the numerical simulation result shows that the algorithm improves the efficiency of resource processing. [ABSTRACT FROM AUTHOR]

Research on the minitype sampler's excavation resistance model of lunar regolith and the optimization of excavation parameters under low-gravity and low atmospheric pressure environment is conducted in this paper. The prediction model of lunar regolith excavation resistance is established, the soil cutting force and the soil penetration force are derived combined with the shear characteristics of lunar soil and its' elastic-plastic constitutive from the triaxial test simulation. On the basis of this model, for the purpose of lower resistance and higher collect ratio, optimal blade angle and blade depth in different bucket widths suitable for the lunar regolith sampling mission are determined by using the self-adapting genetic algorithm. The simulation results indicate that optimal blade angle and blade depth corresponding, to different blade widths exist. With increase of the blade width, the optimal blade depth becomes larger, and the blade angle becomes smaller. [ABSTRACT FROM AUTHOR]

A general non-smooth trajectory optimization approach is developed in the present paper. The mesh refinement procedure based on data compress for dyadic grids is improved to increase efficiency, usability, and flexibility, and is then combined with the local collocation method which takes advantage of scaling, sparsity and numerical differentiation of NLP. Numerical examples of several challenging non-smooth trajectory optimization (including bang-bang control and so on) demonstrate that: (1) the approach solves non-smooth trajectory optimization rapidly with high accuracy, and captures non-smooth regions exactly with density mesh; (2) the approach captures non-smooth regions of states although the mesh is refined according to controls ; (3) for the local collocation method, it is better to refine the mesh rather than divide the non-smooth trajectory into multiple segments. [ABSTRACT FROM AUTHOR]

Aiming at reducing the huge amount of computation in separated modular spacecraft system optimization, in this paper, a new method for the separated spacecraft system optimization based on hierarchical structure is introduced. This method decomposes the system optimization problem to three hierarchies: the exterior cycle optimizes the number of modules and the height of orbit, the middle cycle optimizes the component configuration, and the interior cycle optimizes launch vehicles and batches. Middle cycle is nested in the exterior cycle, while the interior cycle is nested in the middle cycle. By this method, the computational cost is largely reduced. The effectiveness of this optimization method is verified in the case study of a virtual earth remote sensing separated modular spacecraft. [ABSTRACT FROM AUTHOR]

Coning effects must be accurately compensated in the attitude updating of the classical strapdown inertial navigation integration algorithm. These effects are not involved in the velocity updating, though the attitude change is being taken into it. The novel velocity error term induced by the coning correction is studied in this paper. These effects as the gyro angular increment data have the influence on the velocity updating in the same way. For the assumed linear ramp model, a two-sample compensation algorithm for the novel velocity error term is deduced in detail by using the two successive integrated angular rate increment and specific force increment measurements. The weighting coefficients are then optimized for best average performance in a specific environment; i. e. the body is exposed to a coning angular vibration about the x axis of the body frame combined with a linear vibration at the same frequency and in phase along the z axis. The simulation results validate that the two-sample optimization algorithm can compensate the integrated term of the novel velocity error effectively. [ABSTRACT FROM AUTHOR]

In traditional Kalman filtering algorithms, optimization estimation cannot be achieved for practical problems because the dynamics system model and noises are unknown. Firstly the impacts of various error sources and interval matrix operations in the traditional Kalman filter are analyzed. The analysis shows that the interval operation can ensure the completeness of set mapping but can not be the optimization. Based on the analysis, a new interval Kalman filtering algorithm is proposed in this paper. In the algorithm, various error sources are reduced to a priori estimation interval and a posterior estimation interval and the interval intersection set operation is adopted to achieve the optimization. This algorithm has comparable computational complexities with the traditional one. Simulations show that the proposed algorithm can achieve a 2dB gain over the traditional Kalman filter in high dynamic navigation and positioning with time-varying noises. [ABSTRACT FROM AUTHOR]

Under the condition of a short sampling period, limited resource and computational capacity, a method for designing reduced-order fault detection filtering algorithm is proposed in this paper. Small perturbation theory and a Taylor series expansion about the balance point are used to linearize the nonlinear dynamics equations of space vehicles. Then the reduced-order fault detection filter is designed for the linear state-space equation. The problem of feasible solution of the reduced-order fault detection filtering algorithm is transformed into a nonconvex optimization problem expressed in terms of linear matrix inequalities. The local optimal solution of the nonconvex optimization is achieved by an alternate mapping algorithm. The reduced-order fault detection filtering algorithm is obtained under the condition that the feasible solution exists. Finally, the reduced-order fault detection algorithm is applied to the fault detection of the yaw control system in a small-scale autonomous helicopter. Simulation results are presented to show effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

Low-thrust phasing maneuver design of Earth circle-orbit satellites is researched in this paper. A semi-analytical phasing parameter analysis method is proposed, and based on that an efficiently accurate design method is developed. First, according to the influence law of thrust direction on phase change rate, functional relationship between phasing parameters are derived by using orbit averaging technique and thrust direction assumption. The key phasing parameters can be obtained by using simple differential correction. Then, the fuel-optimal phasing orbit design under the condition of complex constraints based on a perturbation model is transformed into a multi-parameter optimization problem by discretizing control law. With the initial guess obtained by the analysis method, the problem can be solved rapidly by using a sequential quadratic programming algorithm. Finally, the simulation results of Geosynchronous orbit low-thrust phasing transfer is presented, it is shown that feasible initial guess can be provided with the analytical method for phasing orbit design, and by using the robust design method, low-thrust phasing trajectory design problem can be solved effectively under the perturbation model. [ABSTRACT FROM AUTHOR]

n order to improve both robustness against disturbances and sensitivity against faults and reduce the design conservativeness for the model uncertainties and unknown inputs, a design method of the H_/H∞ fault detection observer is presented in this paper, the non-convex constraint formulations can be converted into linear matrix inequality (LMI) constraints through lossless S-procedure, the design of the H_/H∞ fault detection observer can be transformed into the convex optimization problems with LMI constraints by making use of Schur theorem. The adaptive threshold generators are designed for decreasing the rates of false alarming. According to the numerical calculation of the convex optimization problems, the design of the fault detection observer process can be easy to achieve. The proposed algorithms guarantee the optimization trade-off between the robustness to the unknown inputs and the sensitivity to faults. Simulation shows that the proposed algorithms ensure the convergence of the residuals quickly and decrease the fault detection time. [ABSTRACT FROM AUTHOR]

Signals of interest (SOIs) extraction is a vital issue in the field of communication signal processing. In this paper, the cyclostationary property of communication signals is incorporated into the constrained ICA (cICA) framework to form a new constrained optimization problem. The approach incorporates cyclostationarity constraints in the ICA process to perform separation and selection of the SOIs simultaneously. Numerical simulations demonstrate the effectiveness and higher performance of the proposed algorithm compared with the conventional ICA algorithms such as FastICA. [ABSTRACT FROM AUTHOR]

Space webs woven out of lightweight and pliable ropes as a kind of crucial on-orbit servicing technique, which have great potential for practical application in areas such as orbit service, spacecraft recovery, orbit cleaning, space interceptor, are webs of a certain configuration formed by projecting. In this paper, ABAQUS is adopted to establish a finite element model for a system of flexible webs with different folding patterns. Metrics on the deployment performance of webs' system are proposed, impacts of different folding patterns on deployment performance parameters are compared, and projecting parameters such as traction mass, projectile angle and projectile velocity are optimized. Simulation results indicate that the folding pattern is the key factor in effectively deploying of webs, and optimistic projecting parameters of webs are obtain within the range of given parameters. [ABSTRACT FROM AUTHOR]