Deployer with Retrievable Capability for Space Applications 1 st - - PowerPoint PPT Presentation

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Deployer with Retrievable Capability for Space Applications 1 st - - PowerPoint PPT Presentation

Modeling a New Concept of Tether Deployer with Retrievable Capability for Space Applications 1 st Symposium on Space Educational Activities Padova, December 11 th , 2015 Gilberto Grassi , Riccardo Mantellato MSc Aerospace Engineering


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Modeling a New Concept of Tether Deployer with Retrievable Capability for Space Applications

Gilberto Grassi⋆, Riccardo Mantellato

⋆ MSc Aerospace Engineering Department of Industrial Engineering

University of Padova

1st Symposium on Space Educational Activities Padova, December 11th, 2015

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Overview

  • 1. Introduction
  • 2. Proposed concept
  • 3. Models & control
  • 4. Simulations
  • 5. Conclusions
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Introduction

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What did we want to do?

  • 1. Model a tether deployer with retrievable capability
  • 2. Simple & reliable
  • 3. Compact & light

Scope & Requirements

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1992 – TSS-1 – 20 km tether

  • 670 kg satellite + tether
  • 4800 kg pallet & support

Tether heritage (1/2)

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1994 – SEDS-II – 20 km tether

  • 33 kg tip mass + tether
  • 10 kg deployer hardware

Tether heritage (2/2)

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Proposed concept

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Openable bail

Proposed concept (1/2)

Fixed spool

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Fixed spool Openable bail Tether

Proposed concept (1/2)

Deployment phase

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Openable bail Tether

Proposed concept (1/2)

Retrieval phase DC motor Fixed spool

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How to control tether motion during deployment?

Proposed concept (2/2)

PD control … Inductive Brake (TSS-like) Low-Inertia (SEDS-like)…

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Proposed concept (2/2)

PD control How to control tether motion during deployment? … Inductive Brake (TSS-like) Low-Inertia (SEDS-like)…

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Proposed concept (2/2)

PD control How to control tether motion during deployment? … Inductive Brake (TSS-like) Low-Inertia (SEDS-like)…

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Models & control

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x y z m

  • θ

l

M

Models (1/2)

Dumbbell tether model

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Mechanical brake (low-inertia) Tether Rollers Actuator Motion Friction

Models (2/2)

x

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Control (1/2)

Reference trajectory optimization – Nelder-Mead algorithm

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Control (2/2)

Tether/probe dynamics PD controller l, l . lref(t), lref(t) control tension T . Reference trajectories feed-forward – lref(t), lref(t) .

  • ε
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Equations (deployment)

LI IB

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LI IB Control Inner friction

Equations (deployment)

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LI IB Control Inner friction

Equations (deployment)

15 mN 150 mN

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Simulations

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Deployment scenario (1/2)

x z Chaser Target E.g. active debris removal local vertical

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Deployment scenario (1/2)

x z Target local vertical E.g. active debris removal Chaser

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Deployment scenario (1/2)

x Target local vertical E.g. active debris removal Chaser Tethered de-orbit package

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Deployment scenario (2/2)

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Deployment scenario (2/2) θ0 lgoal l0 .

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( ): insufficient initial velocity ( ): successful deployments

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Results

Simulations results ( ): insufficient brake authority control

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( ): insufficient initial velocity ( ): successful deployments

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Results

Simulations results ( ): insufficient brake authority control Required higher launch velocity

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( ): insufficient initial velocity ( ): successful deployments

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Results

Simulations results ( ): insufficient brake authority control Less control authority w.r.t. IB

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Deployment example (1/3)

Successful deployment

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Deployment example (2/3)

Deployment failure – insufficient launch velocity

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Deployment example (3/3)

Deployment failure – insufficient deployer control authority

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Conclusions

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Conclusions

Low-inertia

  • 1. Easier ground test phase
  • 2. Requires less energy (T0)
  • 3. Higher tolerance of design

inaccuracies (less parts in

  • synch. motion)

Inductive brake

  • 1. More control authority
  • 2. Less actuators
  • 3. Some critical issues during

deployment are addressed

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Conclusions

Low-inertia

  • 1. Easier ground test phase
  • 2. Requires less energy (T0)
  • 3. Higher tolerance of design

inaccuracies (less parts in

  • synch. motion)

Inductive brake

  • 1. More control authority
  • 2. Less actuators
  • 3. Some critical issues during

deployment are addressed

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  • Questions? -
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2007 – YES2

  • 12 kg endmass + tether
  • 24 kg deployment hardware

Extras – YES2

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Extras – motion equations

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Extras – motion equations

Tether tension (control) Gravity gradient Centrifugal Convective Stabilizing if l > 0 .

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Low-inertia Inductive brake Higher inner friction in IB due to more sliding parts

Extras – system parameters

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Extras – deployment scenario

LH LV C LV C T@eo d T@bod

No relative motion

T@bod ≡ T@eod Easier deployment but higher vrel @eod!

Relative motion

LH

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θ0 values chosen in the simulations

Extras – deployment scenarios

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Extras – Nelder-Mead algorithm

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Extras – Nelder-Mead algorithm

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Extras – abort capability

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p d x 2α α Mechanical brake

Extras – mechanical brake

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d x 2α α p α x d/p = 3

Extras – models

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d x 2α α p α 9 cm 60° x d/p = 3

Extras – models

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What could we do? New docking techniques

Extras – applications

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Extras – DC motor

J R τ

  • V