Deployment of a foldable tensegrity‐membrane system via configuration transitions using linear parameter‐varying control

Abstract

Controlled deployment of a foldable tensegrity-membrane system is investigated in this article. A membrane folding technique referred to as the spiral folding pattern is applied to the attached membrane to achieve compact folded shapes for the system. The foldable tensegrity-membrane system experiences transitions between two system configurations (i.e., the tensegrity configuration and the tensegrity-membrane configuration) due to the variation of membrane loading states during system deployment. A closed-loop control strategy consisting of two linear parameter-varying (LPV) controllers is designed based on control-oriented models to regulate system dynamics. A nonlinear finite element model is used to examine the control performance. Senor noise is considered in another nonlinear finite element simulation to examine the robustness of the designed controllers. K E Y W O R D Scontrol-oriented model, equilibrium conditions, foldable tensegrity-membrane systems, LPV control, nonlinear finite element model | INTRODUCTIONFolding and deployment techniques enable structures and architectures of large dimensions to be stowed during transportation and to be deployed at operational states. Such deployable structure concepts meet design requirements of large deployable spacecraft, leading to several successful applications such as the James Webb Space Telescope (JWST) 1 and NASA's Soil Moisture Active Passive (SMAP) spacecraft. 2 Folding mechanisms were employed to stow the primary and secondary mirrors, membrane sunshields, and the overall telescope to ensure that the folded JWST fits the fairing of a launch vehicle. 3 As a key system component of NASA SMAP spacecraft, a 6-m AstroMesh-Lite reflector, consisting of a truss support structure and a membrane surface, could be stowed to reduce its envelope during launch and be deployed in orbit by controlling the shape of the truss support structure. 4 Folding techniques also enable large spacecraft components such as membranes, solar arrays, and thermal protection panels to be folded to achieve compact packaged shapes. Recently, an ultralight deployable space structure composed of independent bending-stiff trapezoid strips and membranes was designed based on a two-stage packaging/folding concept. 5,6 An origami-based folding concept was recently developed to ensure that an aeroshell of a Mars entry vehicle could be stowed efficiently during the launch phase and be deployed during the entry phase to perform vehicle thermal protection. 7 An origami folding pattern was employed in the design of large spacecraft arrays to achieve self-deployment, self-stiffening, and retraction. 8 Membrane folding patterns such as rotationally skew folding, spiral folding, circumferential folding, and curved circumferential