Continuous precise predefined-time attitude tracking control for a rigid spacecraft

Abstract

This paper designs a new predefined-time attitude tracking control algorithm for a rigid spacecraft with uncertain inertia matrix and disturbance. The main feature of the controller is that the attitude tracking error can converge to zero precisely within a user-predefined time, whose upper bound is an explicit parameter that can be selected arbitrarily. The whole control process is divided into two stages, and the control law is composed of an integral-type invariant partial control law and a two-stage partial control law. In the first stage, classic backstepping control technique is applied to guarantee bounded attitude tracking error. In the second stage, a novel time-varying tuning function vector is introduced into backstepping design, regulating attitude tracking error to zero accurately in a predefined time. It is analyzed that the control torque is always continuous with respect to time, even at the connection time between two control stages. Simulation and comparison studies show the effectiveness and superiority of the proposed controller.