Abstract
This paper investigates the fixed-time coordinated control problem of six-degree-of-freedom (6-DOF) dynamic model for multiple spacecraft formation flying (SFF) with input quantization, where the communication topology is assumed directed. Firstly, a new multispacecraft nonsingular fixed-time terminal sliding mode vector is derived by using neighborhood state information. Secondly, a hysteretic quantizer is utilized to quantify control force and torque. Utilizing such a quantizer not only can reduce the required communication rate but also can eliminate the control chattering phenomenon induced by the logarithmic quantizer. Thirdly, a 6-DOF fixed-time coordinated control strategy with adaptive tuning laws is proposed, such that the practical fixed-time stability of the controlled system is ensured in the presence of both upper bounds of unknown external disturbances. It theoretically proves that the relative tracking errors of attitude and position can converge into the regions in a fixed time. Finally, a numerical example is exploited to show the usefulness of the theoretical results.
Highlights
We are motivated to deal with the problem of fixed-time 6-DOF adaptive coordinated control for multiple spacecraft formation flying (SFF) with input quantization under directed communication topology. e main contributions of this paper are highlighted as follows: (1) the communication topology among follower spacecraft is described by a directed graph, which will bring more challenges than the case that the communication topology among follower spacecraft is described by an undirected graph
(2) A novel multispacecraft nonsingular fixed-time terminal sliding mode (FTTSM) based on a 6-DOF dynamic model is designed, on which each spacecraft converges to its desired states while keeping synchronization with other formation spacecraft
The fixed-time 6-DOF coordinated control problem has been studied for multiple spacecraft formation with input quantization under directed communication graph
Summary
2.1. 6-DOF Dynamic Model. e 6-DOF dynamic model of spacecraft formation is represented as follows [8]:. E 6-DOF dynamic model of spacecraft formation is represented as follows [8]:. To eliminate the control chattering phenomenon induced by logarithmic quantizer, a hysteretic quantizer is used to quantify control torque and force in this paper, which is similar to [45]. From the definition of ρ, we can see that the smaller parameter ρ is, the coarser the hysteretic quantizer becomes [45]. For deriving the 6-DOF fixed-time coordinated controller, the lemmas are made as follows. Where α, β, p, g ∈ R+, pk < 1, gk > 1, and 0 < υ < ∞. en, the origin of system (17) is practical fixed-time stable and the residual set of the solution satisfies
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