Sub-Structuring Modeling of Large Space Truss Structures for Structure/Control Optimization in Presence of Parametric Uncertainties

TL;DR

This paper introduces a novel analytical sub-structuring modeling approach for large space truss structures, enabling robust structure/control co-design under parametric uncertainties, demonstrated through an optimization case for high pointing antenna performance.

Contribution

A new sub-structuring modeling methodology for large truss structures that incorporates parametric uncertainties and supports robust co-design with control optimization.

Findings

Accurate vibration modeling of large truss structures.

Effective integration of multidisciplinary optimization and robust control.

Enhanced pointing performance with reduced structural mass.

Abstract

Modern and future high precision pointing space missions face increasingly high challenges related to the widespread use of large flexible structures. The development of new modeling tools which are able to account for the multidisciplinary nature of this problem becomes extremely relevant in order to meet both structure and control performance criteria. This paper proposes a novel methodology to analytically model large truss structures in a sub-structuring framework. A three dimensional unit cube element has been designed and validated with a Finite Element commercial software. This model is composed by multiple two-dimensional sub-mechanisms assembled using block-diagram models. This constitutes the building block for constructing complex truss structures by repetitions of the element. The accurate vibration description of the system and its minimal representation, as well as the possibility of accounting for parametric uncertainties in its mechanical parameters, make it an appropriate tool to perform robust Structure/Control co-design. In order to demonstrate the strengths of the proposed approach, a co-design study case is proposed by combining a multidisciplinary optimization approach based on particle swarm algorithm and multiple structured robust Hinf-synthesis. This has been used to optimize the pointing performances of an high pointing antenna, minimizing the perturbations coming from the Solar Array Mechanisms (SADM) of two solar panels, performing active control by means of multiple proof mass actuators, and simultaneously reduce the mass of the truss-structure which connects the antenna to the main spacecraft body.