Precision pointing H∞ control design for absolute, window-, and stability-time errors

Ott, Thomas; Fichter, Walter; Bennani, Samir

doi:10.1007/s12567-012-0028-z

Cited by 13 publications

(10 citation statements)

References 11 publications

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“…The RPE index represents the statistics of the instantaneous angular difference between the pointing vector LOS and its short-time average in a time interval t ∆ . In the frequency domain this filter corresponds to an high-pass weight [51] applied to the system:…”

Section: Fine Pointing Performance Definitionmentioning

confidence: 99%

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

Finozzi¹,

Sanfedino²,

Alazard³

2022

Preprint

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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 H ∞ -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.

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Section: Fine Pointing Performance Definitionmentioning

confidence: 99%

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

Finozzi¹,

Sanfedino²,

Alazard³

2022

Preprint

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“…However, a high amplitude S i K will also cause an amplification of the noise contribution to the pointing errors

{boldM}_{d_{n} \to e_{p}}

and potentially conflict with the requirements on the robust stability and control effort performance. Based on the prior considerations, the pointing performance weight W p was chosen as

W_{p} = W_{p \max} W_{RPE} with W_{p \max} = ϵ_{\max}^{- 1} I_{2}; W_{RPE} = \frac{t_{Δ} s ((), t_{Δ} s + \sqrt{12})}{{false(t_{Δ} s false)}^{2} + 6 false(t_{Δ} s false) + 12} I_{2} and \begin{matrix} centerarray \\ array t_{normalΔ} = 20 ms \\ array ε_{\max} = 0.65 mas / \sqrt{Hz} . \end{matrix}

Here, W RPE calculates the RPE signals p RPE (shown in Figure ) across a window time t Δ = 20 ms based on the absolute pointing errors

boldp = {false[θ_{a} θ_{b} false]}^{sans-serif T}

using the frequency domain rational approximation given in other works . Subsequently, W p max is used to comply with the pointing stability requirements and guarantees, if holds, an upper bound ε max on the ASD of the RPE signals p RPE .…”

Section: Performance Objectives and Controller Designmentioning

confidence: 99%

“…Here, W RPE calculates the RPE signals p RPE (shown in Figure 8) across a window time t Δ = 20 ms based on the absolute pointing errors p = [ a b ] T using the frequency domain rational approximation given in other works. 40,44,45 Subsequently, W pmax is used to comply with the pointing stability requirements and guarantees, if (32) holds, an upper bound max on the ASD of the RPE signals p RPE .…”

Section: Output Weights and Performance Definitionsmentioning

confidence: 99%

Robust microvibration mitigation and pointing performance analysis for high stability spacecraft

Preda

Cieslak

Henry

et al. 2018

Intl J Robust & Nonlinear

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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.

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“…The pointing performance is defined as the relative pointing error (RPE) across a window time t ∆ = 100 ms based on the abso- lute pointing error θ SC using the frequency domain filter [11,12]:…”

Section: Pointing Performancesmentioning

confidence: 99%

A Novel Dynamic Model of a Reaction Wheel Assembly for High Accuracy Pointing Space Missions

Sanfedino

Alazard

Pommier-Budinger

et al. 2018

Volume 3: Modeling and Validation; Multi-Agent and Networked Systems; Path Planning and Motion Control; Tracking Control System

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This paper proposes a novel dynamic model of a Reaction Wheel Assembly (RWA) based on the Two-Input Two-Output Port framework, already presented by the authors. This method allows the user to study a complex system with a sub-structured approach: each sub-element transfers its dynamic content to the other sub-elements through local attachment points with any set of boundary conditions. An RWA is modelled with this approach and it is then used to study the impact of typical reaction wheel perturbations on a flexible satellite in order to analyze the microvibration content for a high accuracy pointing mission. This formulation reveals the impact of any structural design parameter and highlights the need of passive isolators to reduce the microvibration issues. The frequency analysis of the transfer between the disturbance sources and the line-of-sight (LOS) jitter highlights the role of the reaction wheel speed on the flexible modes migration and suggests which control strategies can be considered to mitigate the residual micro-vibration content in order to fulfil the mission performances.

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Precision pointing H∞ control design for absolute, window-, and stability-time errors

Cited by 13 publications

References 11 publications

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

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

Robust microvibration mitigation and pointing performance analysis for high stability spacecraft

A Novel Dynamic Model of a Reaction Wheel Assembly for High Accuracy Pointing Space Missions

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