Deployable Prototype Testing and Control Allocation of the CABLESSail Concept for Solar Sail Shape Control and Momentum Management

TL;DR

The paper tackles momentum management for large, flexible solar sails by introducing the Cable-Actuated Bio-inspired Lightweight Elastic Solar Sail (CABLESSail), which uses cable actuation along deployable booms to shape the sail and counteract solar radiation pressure torques. It combines a deployable 2 m composite lenticular boom prototype with a data-driven control allocation algorithm that maps desired momentum-management torques to boom-tip deformations, enabling on-board computation. Through small-scale prototype tests and comprehensive simulations, the study demonstrates robust torque generation despite membrane-shape uncertainty and shows that yaw/pitch torques comparable to state-of-the-art actuators can be achieved with minimal residual roll torque, while roll torques are enhanced beyond traditional methods. The work significantly advances toward TRL 3 by validating deployable hardware and a practical, onboard-capable control framework, with clear pathways to further TRL progression through larger-scale testing, software-in-the-loop validation, and potential extensions to drag-modulation applications.

Abstract

This paper presents prototype testing and a control allocation algorithm for the Cable-Actuated Bio-inspired Lightweight Elastic Solar Sail (CABLESSail) concept aimed at performing momentum management of a solar sail. CABLESSail uses actuated cables routed along the structural booms of the solar sail to control the shape of the solar sail and changes the solar radiation pressure disturbance torques acting on it. Small-scale prototype tests of CABLESSail are presented in this paper, which demonstrate the effectiveness of cable actuation on deployable booms. A novel control allocation method is also presented in this paper that provides a computationally-efficient manner to determine the deformations required in each of the structural booms to impart the desired momentum management torque on the solar sail. Numerical simulation results with the proposed algorithm demonstrate robustness to uncertainty in the shape of the sail membrane, resulting in reliable generation of momentum management torques that exceed or meet the capabilities of state-of-the-art solar sail actuators. Both the prototype tests and control allocation methods presented in this paper represent key steps in raising the technology readiness level of the CABLESSail concept.

Figures (18)

• Figure 1: The CABLESSail concept, which involves adjusting the tensions in cables routed along the length of the solar sail's booms to control the boom's bending deformation. Each boom has two actuating cables that allow for control of the boom's out-of-plane deformation. The body frame is defined by the $b_1$ (yaw), $b_2$ (pitch), and $b_3$ (roll) axes.
• Figure 2: CABLESSail actuation modes: (a) yaw-pitch mode involving a single boom deformation and (b) roll mode involving coordinated deformation of all booms.
• Figure 3: Depiction of a simulated sail membrane shape.
• Figure 4: Monte Carlo static simulations of (a) yaw, (b) pitch, and (b) roll maneuvers. Histogram of change in torque generated across all simulated sail membrane shapes.
• Figure 5: Images of (a) a close-up of the TRAC boom prototype with a single actuating cable and (b) the vertical prototype testbed with a sail tension simulation device and the Vicon motion capture system in the background.