Robust microvibration mitigation and pointing performance analysis for high stability spacecraft

Abstract

Summary This paper deals with the development of a mixed active‐passive microvibration mitigation solution capable of attenuating the transmitted vibrations generated by reaction wheels to a satellite structure. A dedicated simulation environment, provided by the European Space Agency and Airbus Defence and Space industries, serves as a support for testing the proposed solution at satellite level. This paper covers modeling, control system design, and worst‐case analysis for a typical satellite observation mission that requires high pointing stability. Combined with a novel disturbance model for the reaction wheel perturbations, the pointing performance and stability requirements are reformulated as bounds on the worst‐case L2 system gains. Subsequently, the active microvibration controller is tuned to manage the conflicting design goals and optimize different trade‐offs between robustness and performance. Finally, robust stability margins and worst‐case performance bounds with respect to various system uncertainties, time‐varying reaction wheel spin rates, actuator saturation, and time delays are obtained using the structured singular value, integral quadratic constraints, and time‐domain nonlinear simulations.

Robust and adaptable dynamic response reshaping of flexible structures

“…A complete explanation of the process used to obtain the structured LPV controllerǨ ∈ using non-smooth  ∞ tools can be found in Refs. [16,17,36]. In the case of the optimization given in (27), a controllerǨ was found to achieve a performance level of = 0.989.…”

“…Over the years, a wide variety [9] of microvibration isolation systems have been developed or proposed in an effort to tackle this problem. Most of them focus on mechanical isolation of the noisy equipment and/or of the sensitive payload from the rest of the spacecraft structure [11][12][13][14][15][16][17]. For some observation missions, active and adaptive optics [18][19][20] are a promising technology to perform wavefront correction and improve pointing stability at the payload level.…”

“…6 illustrates the internal structure of this overall LFT model and the interconnections between the various subcomponents. This block diagram LFT representation of G sys offers some advantages over the system level description given in (16). Firstly, this method of assembly can be more versatile since the different component blocks can be easily interchanged with others from an existing library (see Ref.…”

“…The truncation errors induced by this model reduction can be included into an additional additive uncertainty model as performed in Ref. [16].…”

“…The controller order n qk = 6, the number of repetitions n K = 6 of the scheduling parameter and the initial values for the controller matrices were chosen after following the iterative procedure detailed in Ref. [16]. To speed up the subsequent optimization, the matrices A K0 , A K1 are constrained to be tridiagonal.…”