As interplanetary missions are increasingly complex, the existing unique mature interplanetary navigation method
mainly based on radiometric tracking techniques of Deep Space Network can not meet the rising demands of
autonomous real-time navigation. This paper studied the applications for interplanetary flights of a new navigation
technology under rapid development-the X-ray pulsar-based navigation for spacecraft (XPNAV), and valued its
performance with a computer simulation. The XPNAV is an excellent autonomous real-time navigation method, and can
provide comprehensive navigation information, including position, velocity, attitude, attitude rate and time. In the paper
the fundamental principles and time transformation of the XPNAV were analyzed, and then the Delta-correction XPNAV
blending the vehicles' trajectory dynamics with the pulse time-of-arrival differences at nominal and estimated spacecraft
locations within an Unscented Kalman Filter (UKF) was discussed with a background mission of Mars Pathfinder during
the heliocentric transferring orbit. The XPNAV has an intractable problem of integer pulse phase cycle ambiguities
similar to the GPS carrier phase navigation. This article innovatively proposed the non-ambiguity assumption approach
based on an analysis of the search space array method to resolve pulse phase cycle ambiguities between the nominal
position and estimated position of the spacecraft. The simulation results show that the search space array method are
computationally intensive and require long processing time when the position errors are large, and the non-ambiguity
assumption method can solve ambiguity problem quickly and reliably. It is deemed that autonomous real-time integrated
navigation system of the XPNAV blending with DSN, celestial navigation, inertial navigation and so on will be the
development direction of interplanetary flight navigation system in the future.
Based on the nonlinear constructive model for magnetostrictive materials proposed by [1], a dynamic model is
established to depict the natural characteristics of electro-magneto-mechanical coupling for magnetostrictive actuators. In
this model, the change of Young's modulus of magnetostrictive materials with the magnetic field and the stress level in
the operating actuators is considered. Due to this feature, the property of nonlinear parametric vibration with time-variant
stiffness is presented in the dynamic characteristic of magnetostrictive actuators. By virtue of the numerical solution of
the equation, the parametric frequency response characteristics of magnetostrictive actuators are obtained.
Simultaneously, the effect of the amplitude of drive current and load mass on the dynamic characteristics of
magnetostrictive actuators are investigated. The results are also compared with relative experimental investigations.
The control model of RLG digital frequency stabilization system, composed of a proportional element, an inertial
element, a nonlinear element and a digital controller, was established. The model parameters were acquired by frequency
sweeping and searching firstly. Then, the principle of frequency stabilization control was presented. The nonlinear
element was linearized by introducing a square wave and Ziegler-Nichols method was used to design a PI controller for
the linearized system whose feasibility was proved by SIMULINK and experiment results. Finally, experiment results
showed that RLG output instability is less than 0.05%, which satisfies the requirement of application.
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