Autonomous Navigation For Spacecraft Based On Image And Starlight

As one of the key technologies for spacecraft's autonomous operation,has been widely developed and paid attention to in these years.For the advantages just like strong autonomy,better real-time,etc.,autonomous optical navigation method has become a current hot issue in autonomous navigation.In this paper,considering the navigation scheme design,system observability analysis and state estimation,the autonomous navigation method based on image and starlight for spacecraft is designed.Specific work is carried out as follows:First,the autonomous optical navigation schemes based on image and starlight are designed.Considering the space environment and sensor characteristic,two schemes based on image and starlight are designed.Then relied on the image-forming principle of optical camera and star sensor,angle and line-of-sight vector of spacecraft to earth and star are deduced so as to obtain the measurement equation.Second,a method about the selection of navigation star is put forward based on the observability target.Geometric and numerical analysis methods are introduced to compare and analyze the observability of the navigation systems.Evaluate the degree of observability for the two navigation methods,compare and analyze the performance of the navigation schemes.Moreover,to let the degree of observability be optimal,a method based on Fisher Information Matrix is put forward for the selection of navigation star so as to improve the performance of autonomous navigation system.Third,the autonomous navigation algorithm for state estimation used for image and starlight measurement is studied.Due to the characteristic of nonlinear and time-varying about dynamics and observation model,Extended Kalman Filter and modified Unscented Kalman Filter are applied to design the spacecraft navigation filter.Then analyze application condition of the two filters to navigation model.At last,the influence about different system causes having on the navigation performance is investigated.With the help of the numerical simulation,the influence of sampling period and sensor accuracy on spacecraft states is analyzed.Monte-Carlo simulation is operated to give the error band about state estimation.The performance about the two navigation systems is analyzed;the influence of the observability degree on navigation accuracy is verified.