Neural-Network Based Finite-Time Coordinated Formation Control for Spacecraft Without Unwinding

Abstract

This paper investigates the problem of rotation matrix-based attitude synchronization and tracking control for spacecraft formation flying exposed to external disturbance and unknown inertial matrix. For the purpose of ensuring finite-time convergence for attitude tracking errors, a hyperbolic tangent function-based sliding mode surface is designed. Based on the sliding mode variable, an adaptive law is proposed to estimate the upper bound of unknown disturbance and radial basis function is employed to approximate unknown system dynamics. The minimum learning parameter algorithm is adopted to reduce the computational burden. It is demonstrated by Lyapunov-based analysis that the sliding mode surface and estimating errors will possess finite-time stability under the presented controller. Finally, results of numerical simulations are exhibited to validate the stability and validity of the proposed controller. INDEX TERMS rotation matrix, finite-time coordinate control, spacecraft formation flying, sliding mode, neural network

Distributed Predefined-Time Attitude Consensus Control for Multiple Uncertain Spacecraft Formation Flying

“…Remark 3: In contrast to the existing finite-time attitude consensus (or synchronization) control of rigid spacecraft [13]- [17], the proposed controller ensures that the upper bound of the settling time can be explicitly defined by user instead of complicated estimation, and has strong robust to the model uncertainties for each spacecraft in formation.…”

“…It is well-known that finite-time stable control is more desirable due to the fast transient, high-precision performance and better disturbance rejection property [12]. Typical existing finite-time distributed control methods for multiple spacecraft can be founded in [13]- [17]. In [13], for multiple stationary leaders, the authors propose a modelindependent control law to guarantee that the attitudes of the followers converge to the stationary convex hull formed by those of the leaders in finite time.…”

“…In [16], a distributed control combining the saturation technique and observer approach is designed for the multiple spacecraft to obtain attitude consensus. In [17], a hyperbolic tangent functionbased sliding mode surface is designed, and an adaptive law is presented to achieve attitude synchronization and tracking control of spacecraft formation flying.…”

“…Secondly, a simple distributed predefined-time consensus control (DPTC) is exploited to solve the robust attitude consensus problem. In comparison with the existing finite-time consensus control in [13]- [17], the proposed DPTC can not only ensure that the upper bound of the settling time can be explicitly defined by user instead of complicated estimation, but also has strong robust to the model uncertainties. A rigorous stability analysis is presented following Lyapunov stability theory.…”