China will launch the “Tianwen-IV” mission around 2030, focusing on the orbiting exploration of Jupiter and Callisto, a moon of Jupiter. As part of this ambitious mission, a main satellite will carry another satellite that will be released in the Jupiter system to continue its journey toward Uranus. Considering the current mission planning, we propose an inter-satellite radio-observation mode that differs from the conventional observation mode of tracking from Earth to precisely determine the orbit of the satellites. Given the significance of the Callisto gravity field model in both science objectives and satellite navigation, we have conducted a series of simulation experiments to evaluate the potential of this inter-satellite range-rate data for accurately estimating the Callisto gravity field. The results obtained from the analysis demonstrate that by utilizing 40 days of ground station observations, it is possible to estimate the gravity field model of Callisto up to a degree of 70. Remarkably, when combining these ground station observations with inter-satellite observations, a comparable level of accuracy can be achieved with just 10 days of observations. Furthermore, with reduced inter-satellite observation noise, accuracy improves, enabling estimation up to 80 degrees or higher. Initial inter-satellite distance selection impacts estimation accuracy. These findings serve as a valuable test bed for the future “Tianwen-IV” mission to perform precise orbit determination and gravity field model estimation to reduce reliance on deep space stations.

Aiming at the flight-instability of the closed-loop system in windy field of three fixed-wing unmanned aerial vehicles (UAVs) formation. In this paper, we design a multi-UAV formation controller to address the flight-stability of multiple UAVs. The problem of flight-stability can be converted to the analysis of dynamic response and steady-state error. The robust control compared with thin membrane control method, it can realize the high speed and close cooperative formation of precision combat. Adding thin membrane is not only capable of reducing the body vibration and steady-state tracking error, but also owns better robustness. The proposed controller can control leader's speed so that follower can track leader in the case of decoupling, while maintaining the consensus of relative speed. The simulation results show that the designed controller integrates the advantages of robust control and thin membrane vibration attenuation. Moreover, this control method can not only improve the response speed, convergence time and stability of the control system, but also realize the aim of the precision cooperative combat ability.

Aiming at the collision between the unmanned aerial vehicles (UAVs) in tracking motion target due to the inconsistency information, we design the unmanned aerial vehicle (UAV) formation cooperative tracking controller and analyze the flight-stability of the designed controller in the case of only knowing the UAV local information. Recently, a Lyapunov guidance vector field approach is proposed to achieve the desired circular trajectory in the paper. The path planning of a single UAV and the Multi-UAVs cooperative formation tracking motion target are simultaneously studied. In the ideal case, a guidance vector field method is proposed for the heading convergence, which has the advantage of analyzing and solving the collision problem between the unmanned aerial vehicles (UAVs). Further, a variable airspeed controller is used to maintain the UAV cooperative formation flight in a circular orbit, and an adaptive estimate is introduced to ensure the flight-stability of a circular orbit in the case of unknown wind and moving targets. In the process of the UAV formation tracking motion targets, we use a variable airspeed controller to achieve the desired angular spacing. In this paper, the designed controller laws are decentralized based on the local information. Meanwhile, the simulation shows that the designed controller has a good the flight-stability in the process of tracking motion target.