In-orbit pointing accuracy and pointing stability are two of the most important technical indicators for ensuring the effective operation of the payload. Traditionally, these two indicators are guaranteed by the attitude control system of the support module. The ever-increasing demands of space missions, along with the flexibility of spacecraft and the presence of both internal and external disturbances, make it a challenge to enhance the accuracy and stability of the attitude control system in the overall design. The Disturbance-Free Payload architecture, which separates the payload module from the support module to provide natural vibration isolation, has been developed and promoted. This article provides an overview of its modeling and control methods, introducing general dynamic equations and advanced motion control techniques. In addition, this article presents the performance verification methods, including the numerical simulation logic, the ground verification platform setup, and the in-orbit model. Written in a tutorial style to familiarize researchers with the essentials, this paper serves as a reference for the design and practice of Disturbance-Free Payload high-performance spacecraft.

This paper introduces time-synchronized convergence in fixed-time control, where all system states converge to the origin at the same time before a fixed time instant. Sufficient Lyapunov conditions are derived for fixed-time synchronized control (FTSC). An enhanced estimation method for synchronized settling time (ST) is proposed, with an explicit formula for its least upper bound (LUB), which reduces overestimation compared to existing methods. A switching-based technique is incorporated into the controller to avoid singularities while maintaining compatibility with the time-synchronized design. Simulation results validate the fixed-time synchronization properties and the improved ST estimation, demonstrating smoother output trajectories and reduced energy consumption.