# Finite-time attitude tracking control for spacecraft based on backstepping method with input saturation

## TL;DR

This paper presents a new control method for spacecraft that ensures stable attitude tracking within a finite time, even with input limitations.

## Contribution

The novelty lies in the design of a chattering-free finite-time controller with input saturation using a hyperbolic function and auxiliary system.

## Key findings

- A finite-time controller with improved adaptation law provides robustness against external disturbances.
- A novel controller ensures control torques remain below a predetermined value using a hyperbolic function and auxiliary system.
- Simulation results confirm the effectiveness of the proposed control strategies.

## Abstract

In this paper, the finite-time attitude tracking control problem for spacecraft based on the backstepping method is addressed. Firstly, a finite-time controller is designed, which can provide robustness for external disturbance by employing an improved adaptation law. Secondly, a novel finite-time controller with input saturation is proposed by introducing the hyperbolic function and auxiliary system to guarantee the control torques below a predetermined value. The above two controllers are continuous, thus, they are chattering-free. Finally, simulation results are presented to illustrate the effectiveness of the control strategies.