Hanqiao Huang

Accurately determining the parameters of an unmodeled spacecraft is crucial. Filtering methods that are resilient to uncertainty, employing dual quaternion frameworks to ascertain orientation and position, introduce a design for an extended Kalman filter based on variational Bayesian inference and dual vector quaternions (VB-DVQEKF) to carry out parameter estimation for a non-cooperative spacecraft. The system kinematics and dynamics are modeled using dual vector quaternions, rendering the representation manifestly concise. The method achieves thoroughness by accounting for the coupled interactions between translational and rotational motions. Furthermore, to address uncertainties in the measurements, a variational Bayesian approach is employed for the dependable simultaneous estimation of state parameters and measurement noise covariance. Mathematical simulations are used to verify the proposed VB-DVQEKF, and its robust capabilities are demonstrated through comparisons with several conventional parameter estimation techniques, including the conventional DVQ-EKF and the Sage–Husa adaptive DVQ-EKF (SH-DVQEKF). Quantitative results based on root-mean-square error (RMSE), convergence time, and final estimation error confirm that the proposed VB-DVQEKF achieves the smallest steady-state error among the compared methods and remains stable under white-burst, gradient (drift), and outlier-type measurement anomalies.

In this paper, a finite-time three-axis stabilization controller for an underactuated rigid spacecraft is proposed based on well-designed hierarchical terminal sliding mode surfaces to handle the insufficiency of control effort and disturbances. Firstly, the attitude kinematic of an underactuated rigid spacecraft is parameterized by the w-z representation and the dynamic model with only two orthogonal torque inputs are presented. Secondly, based on the terminal sliding mode theory, a three-hierarchized sliding surface is established. A finite-time stable control law is derived by the Filippov equivalence theorem and the principle of sliding mode control. The finite-time stability is proved by the Lyapunov theory. Finally, the high performance of the proposed control approach is verified through numerical simulations and comparisons with state-of-the-art studies.

This work addresses distributed fixed-time bearing-only formation stabilization for multi-agent systems lacking shared orientation knowledge. Addressing the challenge of missing global coordinate alignment in multi-agent systems, this work introduces a novel distributed estimator ensuring almost globally fixed-time convergence of orientation estimates. Leveraging this estimator, we develop a distributed bearing-only formation control law specifically designed for agents governed by double-integrator dynamics, guaranteeing fixed-time convergence. Comprehensive stability analysis proves the almost global fixed-time stability of the overall closed-loop system. Crucially, the proposed control strategy drives actual formation to achieve the desired geometric pattern with almost global exponential convergence within a fixed time bound. Rigorous numerical experiments corroborate the theoretical framework.

This paper addresses the global finite-time pose control problem of a leader-following dual spacecraft six-degree-of-freedom (6-DOF) formation in the twistor framework, where velocity measurements of the follower spacecraft are not available. Firstly, twistors are employed to describe the coupled pose motion of the follower spacecraft to eliminate redundant parameters and normalization constraints. Secondly, a uniformly globally finite-time stable controller without velocity measurement for the follower spacecraft is proposed by employing homogeneous theory, in which a hysteretic switching strategy is introduced based on hybrid control method to avoid unwinding phenomena and enhance robustness to measurement noise. Subsequently, a hybrid filter is designed to provide damping for the controller due to the absence of velocity feedback. Finally, the uniform global finite-time stability is rigorously proved. The effectiveness of the proposed method is demonstrated by numerical simulations and the results show that the position and attitude integral time-weighted absolute errors (ITAEs) of the hybrid controller reduce by 3.34% and 29.74% respectively, compared to those of the similar continuous controller.

Aiming at the problem of multiple unmanned aerial vehicles (UAVs) cooperatively intercepting a maneuvering target, this paper proposes a cooperative guidance law with less energy consumption and a newly accurate time-to-go estimation algorithm in the two-dimensional (2D) plane. Firstly, based on the relative motion equations between UAVs and the target on the 2D plane, the line-of-sight (LOS) direction and the LOS normal direction models are established. Then, based on the distributed model predictive control (DMPC) theory, DMPC cooperative guidance laws are designed in two directions. This guidance law can ensure that all UAVs intercept the maneuvering target at the expected LOS angle at the same time and reduce the energy consumption during the guidance process. Then, a new time-to-go estimation algorithm is designed, which can reduce the time-to-go estimation error and improve the cooperative accuracy. Finally, the simulation results show that the DMPC cooperative guidance law reduces energy consumption by more than 50% compared to other guidance laws and the proposed time-to-go estimation algorithm improves the accuracy by 200% compared to traditional methods.

A twistor-based position-attitude integrated tracking control scheme is proposed for six-degree-of-freedom (6-DOF) leader-following dual spacecraft formation, which achieves global finite-time stability by combination of the hybrid system theory and homogeneous theory. Firstly, the coupled 6-DOF relative motion equations of dual spacecraft formation are established based on twistors to simplify the design of the controller. Secondly, a hybrid pose tracking scheme is constructed to get rid of the topological constraint of attitude motion, which, meanwhile, avoids singularity and unwinding phenomena. Thirdly, the global finite-time stability of the closed-loop system is proved rigorously via the homogeneous theory and Lyapunov stability theory. Finally, numerical simulations are carried out to demonstrate the effectiveness of the proposed control scheme, and the comparisons with asymptotic control schemes show its superiority