Zhaowei Sun

Sliding-mode control for staring-mode spacecraft using a disturbance observer

Abstract This article studies the attitude control problem for spacecraft staring-mode observation. The staring mode of spacecraft is initially presented, and its advantages for observation are analysed. Then, based on the dynamic equation and kinematic equation using error quaternion and angular velocity error, a sliding-mode controller is designed to improve control effect, which prolongs observation time and enhances observation precision. Afterwards, a disturbance observer is devised and included in this proposed controller to reduce inherent chattering of sliding-mode control and to improve the stability of the spacecraft platform. Besides, the convergence of the proposed disturbance observer is proved theoretically. Finally, simulations are performed, and the results demonstrate that the proposed controller has quicker response, better robustness to uncertainty of spacecraft inertia parameters and external disturbance, and effectively weakens the chattering.

A satellite system distributed simulation design and synchronous control

Based on the RTPS protocol and the NDDS network messaging middleware, a distributed real-time simulation network of satellite system is developed with Constellation software. Considering the structure feature of actual satellite, the module decomposition technique of distributed simulation is discussed in this paper. And with the RTPS protocol and NDDS network middleware, a synchronous control of the simulation network is designed and practiced to coordinate the simulation process. Finally, in order to test the distributed simulation performance, two kinds of satellite attitude control procession are simulated with real-time distributed simulation network. Compared with the results of Matlab integrated simulation, it shows that the distributed simulation network is a good platform for satellite design and the synchronous control method is effective.

The Satellite Optimization Design Using Normal Cloud Model Method

Satellite design is a complex and systematic project. In the design process, due to the complexity of the relations among different disciplinary and the coupling of design variables, the efficiency of the optimization design is not efficiently. Recently cloud computing has been widely used in intelligent control, data mining, optimization computation and the other fields. The normal cloud model based on the normal distribution is an important cloud model for cloud computing and has been a wide range of adaptability. In this paper, the normal cloud model is in combination with evolutionary algorithm. With the idea of evolutionary algorithm, the velocity and direction of optimized search can be controlled by the cloud droplets generated by the normal cloud model. Numerical results indicate the high quality of the algorithm on precision stability and convergence rate and improve the efficiency of the satellite optimization design.

The satellite optimization design using collaborative optimization method based on normal cloud model

Collaborative optimization is a good method for solving multidisciplinary optimization design of the complex system. Satellite design is a complex and systematic project, the efficiency of the traditional optimization design methods are not efficiently. Recently cloud computing has been widely used in intelligent control, data mining, optimization computation and the other fields. The normal cloud model based on the normal distribution is an important cloud model for cloud computing and has been a wide range of adaptability. In this paper, the normal cloud model is in combination with collaborative optimization. With the structure of the collaborative optimization, the velocity and direction of optimized search can be controlled by the cloud droplets generated by the normal cloud model. Numerical results indicate the high quality of the algorithm on precision stability and convergence rate and improve the efficiency of the satellite optimization design.

Relative navigation algorithm research of chaser spacecraft

In this paper, the relative navigation algorithm of chaser spacecraft with orbit maneuvering is investigated. Based on the relative motion dynamic model and linear relative measurement model, a robust H∞ filter for chaser spacecraft is proposed, which contains affine norm-bounded uncertainties, disturbances, and non-Gaussian noise. The necessary and sufficient conditions for the existence of robust H∞ filter are obtained in terms of a linear matrix inequality(LMI). The filter design is then cast into a convex optimization problem subject to LMI constraints. The numerical simulation results show that the relative position precision is 0.1m and the relative velocity precision is 0.02m/s when the chaser spacecraft has orbit maneuvering, which illustrates the effectiveness and advantage of the proposed navigation algorithm. 1 2

Quaternion-based attitude maneuver hardware-in-the-loop simulation for micro satellite

The paper presents a quaternion-based attitude control algorithm which is subject to control input constraints for rigid spacecrafts. Lyapunov theory is employed to prove the global asymptotic stability of the zero equilibrium points of the close loop system. Also the algorithm is validated by the corresponding hardware-in-the-loop (HIL) simulation using a single-axis air bearing table and other hardware. And the simulation results indicate that the algorithm can efficiently accomplish the attitude maneuver.

Attitude fuzzy logic controller design of a staring-imaging satellite in LEO

A fuzzy logic controller is designed for the attitude control of a staring-imaging satellite in LEO. The attitude kinematic and dynamic equations based-on Euler-Angle representations are developed; then, a FLC (Fuzzy Logic Control) law is designed for a staring-imaging satellite; finally, the simulations are performed. Comparing with traditional control methods, the method proposed here has quick convergence and robustness.

Autonomous guidance for proximity to target spacecraft

This paper presents the guidance algorithms of chase spacecraft for autonomous proximity to target spacecraft. The process of autonomous proximity is initially divided into three phases including proximity maneuver, fly-around maneuver and final approach. Based on the Hill equation, the characteristic of each phase is analyzed and then the criteria to design guidance algorithm is proposed. Then, the multi-pulse algorithm is adopted in proximity maneuver and final approach phases, capable of achieving the maneuver in any direction and orbit plane. Different orbit is then planned in each phase in accordance with mission requirements and proposed criteria. Finally, simulation is performed to prove this guidance algorithm. The Offered is an easy way for engineering realize, the analyses and opinions included in this paper can be generic applied in the future space tasks.

Research on the control algorithm of the acousto-optic steering system for intersatellite optic communications

This paper presents an adaptive model reference scheme for laser-beam steering by an acousto-optic steering system which is a novel nonmechanical control system. The controller this paper designs effectively solves the optical communication system performance worsening problem because of the nonlinearity and the parameters drift of the acousto-optic devices and the pointing error of the satellite platform vibration. The hyperstability theory is introduced to determine the adaptive parameters, which ensures the system stabile. The simulation results indicate that the controller can effectively improve the tracking precision and suppress the strong coupling of the azimuth and elevation channel and the satellite platform vibration, so the control scheme is proved to be valid and reliable.

Computation model of image motion velocity for space optical remote cameras

The computation of image motion velocity is the premise of high resolution optical imaging. To solve this problem, the model of image motion velocity for spaceborne cameras is established in this paper. The positions of a target and the pixel plane are expressed in the camera coordinate system based on five coordinate systems and multiply coordinate translations. The calculation formulas of target position and image motion velocity are deduced. The method, in which the orbit and attitude parameters are considered as a whole, is applicable for complex imaging missions and general orbits. The practical value of the study lies in image motion velocity compensation, drift angle compensation, and the location of observed target. Finally, the mathematical simulation shows that the model and the derivation are correct under several typical applications.