Optimal Attitude Control of Large Flexible Space Structures with Distributed Momentum Actuators

Abstract

Recent spacecraft mission concepts propose larger payloads that have lighter, less rigid structures. For large lightweight structures, the natural frequencies of their vibration modes may fall within the attitude controller bandwidth, threatening the stability and settling time of the controller and compromising performance. This work tackles this issue by proposing an attitude control design paradigm of distributing momentum actuators throughout the structure to have more control authority over vibration modes. The issue of jitter disturbances introduced by these actuators is addressed by expanding the bandwidth of the attitude controller to suppress excess vibrations. Numerical simulation results show that, at the expense of more control action, a distributed configuration can achieve lower settling times and reduce structural deformation compared to a more standard centralized configuration.

Figures (9)

• Figure 1: Very Large Space Telescope Concepts illustrating the growing demands for larger-aperture space telescopes from the space science community kuang2024design.
• Figure 2: Notional frequency spectrum of spacecraft disturbances (bottom), rigid and flexible body modes (middle) and typical vibration suppression strategies (top) blackmore2011instrument.
• Figure 3: Centralized and distributed actuator attitude control system architectures. Both scenarios have a similar total angular momentum capacity and maximum torque in all axis, only differing in the location of the actuators.
• Figure 4: Five lowest vibration frequency mode shapes of the flexible structure. The first two modes are strongly coupled to the rigid body rotation of the structure around the X and Y axis.
• Figure 5: High-level system architecture for the flexible structure controller.