The optical navigation errors of Mars probe in the capture stage depend closely on which targets are selected to be observed in the Mars system.As for this problem,an integrated navigation scheme is proposed wherein the optical observation is aided by one-way Doppler measurements.The errors are then analyzed respectively for the optical observation and one-way Doppler measurements.The real-time calculating scheme which exploits the extended Kalman filter(EKF)framework is designed for the integrated navigation.The simulation tests demonstrate that the errors of optical navigation,which select the Mars moon as the observation target,are relatively smaller than those in the Mars-orientation optical navigation case.On one hand,the integrated navigation errors do not depend on the selecting pattern of optical observation targets.On the other hand,the integrated navigation errors are significantly reduced as compared with those in the optical-alone autonomous navigation mode.
