Parameter-Independent Event-Triggered Implicit UKF for the Celestial Navigation Using Time Delay Measurement

Abstract

Celestial navigation using time delay measurement is an innovative autonomous navigation method. To calculate the equivalent measurement, the numerical method needs to be applied, which is time-consuming. The event-triggered mechanism intermittently and aperiodically processes measurements by judging if the update error has changed drastically. However, its performance is greatly affected by the constant threshold. To solve this problem, a parameter-independent event-triggered implicit unscented Kalman filter (UKF) is proposed and applied to the celestial navigation using time delay measurement. The innovation at the current moment and the updated estimate covariance at the last moment are compared with the previous value instead of the constant threshold. The event is automatically triggered when the accuracy of the state estimate is low. Simulation results indicate that the proposed parameter-independent event-triggered implicit UKF can reduce the running time by reducing unnecessary measurement updates, whose performance will not be affected by any parameter or window size. In a word, the proposed method substitutes the dynamic threshold for the constant threshold, ensuring that its performance will not be affected by any parameter or window size.

Analysis and Compensation of Sun Direction Error on Solar Disk Velocity Difference

“…T is the measurement function of the integrated navigation method. Since Equations ( 14), (16), and ( 18) are all nonlinear, the unscented Kalman filter (UKF) can be used to estimate the spacecraft's navigation information [33].…”

“…Thus, autonomous navigation has attracted wide attention at home and abroad due to its real-time performance and low operation cost [14,15]. Celestial navigation is an effective autonomous navigation method for spacecraft to explore deep space [16]. According to different measurement information, the existing celestial navigation methods fall into three categories: celestial navigation based on star angle [17][18][19], celestial navigation based on X-ray pulsar [20,21], and celestial navigation based on Doppler velocity [22,23].…”