Research On Autonomous Navigation Of Mars Probe

With the improvement of onboard computer and measure technologies,autonomous navigation has been applied more widely in deep space mission to reduce dependence on ground TT&C.Mars is a significant object of deep space exploration,and autonomous navigation of Mars probe is very important to Mars exploration mission.The dissertation studies the mothed of autonomous navigation in cruise phase,capture phase and orbiting phase of Mars probe.At first,according to the characteristics of cruise phase,it has been study that the autonomous navigation by combining optical observation of Martian moon and sun radial velocity measure based on Doppler shift of solar spectrum.The measure model of right ascension and declination by optical observation of Martian moon is proposed,which can eliminate probe attitude measure error and sensor installation error.Then,according to the characteristics that ground deep stations participate in capture phase,it is proposed that probe receives one-way radio signal transmitted from ground deep station and acquires accurate velocity data.It can improve effectually navigation precision by the accurate velocity data combing optical observation of Martian moon in approaching Mars phase.The mothed of estimating orbit thrust parameters is set up in orbit maneuver process.Meanwhile,combining acceleration data by inertial measurement,the thrust parameters is estimated accurately and navigation precision is improved in orbit maneuver phase.For probe orbiting Mars phase,it has been study that autonomous navigation method using optical measure of Martian moon,satellite-to-satellite tracking measure(SST)and X-ray pulsar measure.That feasible autonomous navigation in the present technical conditions by accurate SST data combing optical measure is proposed,which can achieve very precision in orbiting phase.Another,a method of X-ray pulsar TOA model based on Mars center is set up,which can cut down the complexity of onboard computing without loss accuracy.The high navigation precision can be achieved that using several measures together in orbiting phase.Considering navigation system is unobservable with SST data only in two body problem,it is proposed that taking into account the high order of Mars gravity the navigation system is observable.It studies that taking nonsingular orbital element as state parameter,based on UKF filter and with high precise dynamics models simultaneously,the autonomous navigation can be realized using SST data only in orbiting phase.The navigation precision is equal with that using SST data combing other measure data.In particular it can acquire more precise semi-axis.The advantage and disadvantage of EKF and UKF has been given by simulation in each phase,which provide reference for how to select filter according to probe's conditions such as onboard computer,measure means,and observation data sampling rate.