phd-nass-introduction/nass-introduction.tex

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\bibliography{nass-introduction.bib}
\author{Dehaeze Thomas}
\date{\today}
\title{Nano Active Stabilization System - Introduction}
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\usepackage{biblatex}

\begin{document}

\maketitle
\tableofcontents

\clearpage

\chapter{Context of this thesis}
\section{Synchrotron Radiation Facilities}
\paragraph{Accelerating electrons to produce intense X-ray}

\begin{itemize}
\item Explain what is a Synchrotron: light source
\item Say how many there are in the world (\textasciitilde{}50)
\item Electron part: LINAC, Booster, Storage Ring \ref{fig:introduction_esrf_schematic}
\item Synchrotron radiation: Insertion device / Bending magnet
\item Many beamlines (large diversity in terms of instrumentation and science)
\item Science that can be performed:
\begin{itemize}
\item structural biology, structure of materials, matter at extreme, \ldots{}
\end{itemize}
\end{itemize}

\paragraph{The European Synchrotron Radiation Facility}

\begin{figure}[htbp]
\centering
\includegraphics[scale=1,width=0.7\linewidth]{figs/introduction_esrf_picture.jpg}
\caption{\label{fig:introduction_esrf_picture}European Synchrotron Radiation Facility}
\end{figure}

\begin{figure}[htbp]
\centering
\includesvg[scale=1,width=0.7\linewidth]{figs/introduction_esrf_schematic}
\caption{\label{fig:introduction_esrf_schematic}Schematic of the ESRF - Over 40 beamlines. Booster, Linac, storage ring}
\end{figure}

\paragraph{3rd and 4th generation Synchrotrons}

\begin{itemize}
\item 4th generation light sources
\begin{itemize}
\item \cite{raimondi21_commis_hybrid_multib_achrom_lattic}
\item[{$\square$}] Picture of 3rd generation ``beam source'' vs 4th generation?
\end{itemize}
\item[{$\square$}] Picture showing Synchrotron ``moore's law''
\end{itemize}

\section{The ID31 ESRF Beamline}
\paragraph{Beamline Layout}

\begin{itemize}
\item[{$\square$}] Beamline layout (OH, EH)
\item ID31 and Micro Station (Figure \ref{fig:introduction_id31_microstation_picture})
Check \url{https://www.esrf.fr/UsersAndScience/Experiments/StructMaterials/ID31}
\url{https://www.wayforlight.eu/beamline/23244}
\item X-ray beam + detectors + sample stage (Figure \ref{fig:introduction_id31_beamline_schematic})
\item Focusing optics
\item Optical schematic with: source, lens, sample and detector.
Explain that what is the most important is the relative position between the sample and the lens.
\item Explain the XYZ frame for all the thesis (ESRF convention: X: x-ray, Z gravity up)
\begin{itemize}
\item[{$\square$}] Add XYZ on figure \ref{fig:introduction_id31_cad}
\end{itemize}
\end{itemize}

\begin{figure}[htbp]
\centering
\includegraphics[scale=1,width=0.8\linewidth]{figs/introduction_id31_cad.jpg}
\caption{\label{fig:introduction_id31_cad}CAD view of the optical hutch with the nano-focusing optics, the micro-station}
\end{figure}

\paragraph{Positioning End Station: The Micro-Station}

Micro-Station:
\begin{itemize}
\item DoF with strokes: Ty, Ry, Rz, Hexapod
\item Experiments: tomography, reflectivity, truncation rod, \ldots{}
Make a table to explain the different ``experiments''
\item Explain how it is used (positioning, scans), what it does. But not about the performances
\item Different sample environments

\item Alternative: \texttt{id31\_microstation\_cad\_view.png} (CAD view)
\end{itemize}

\begin{figure}[htbp]
\centering
\includegraphics[scale=1,width=0.49\linewidth]{figs/introduction_id31_microstation_picture.png}
\caption{\label{fig:introduction_id31_microstation_picture}Picture of the ID31 Micro-Station with annotations}
\end{figure}

\paragraph{Science performed on ID31}

\begin{itemize}
\item Few words about science made on ID31 and why nano-meter accuracy is required
\item Typical experiments (tomography, \ldots{}), various samples (up to 50kg), sample environments (high temp, cryo, etc..)
\begin{itemize}
\item Alignment of the sample, then
\item Reflectivity
\item Tomography
\item Diffraction tomography: most critical
\end{itemize}
\item Example of picture obtained (Figure \ref{fig:introduction_id31_tomography_result}) with resolution
\end{itemize}


\texttt{introduction\_exp\_scanning} and \texttt{introduction\_exp\_scanning\_image}

\begin{figure}[htbp]
\centering
\includegraphics[scale=1,width=0.49\linewidth]{example-image-c.png}
\caption{\label{fig:introduction_id31_tomography_result}Image obtained on the ID31 beamline}
\end{figure}

\section{Need of accurate positioning end stations with high dynamics}
\paragraph{A push towards brighter and smaller beams\ldots{}}

Improvement of both the light source and the instrumentation:
\begin{itemize}
\item EBS: smaller source + higher flux
\item Better focusing optic (add some links): beam size in the order of 10 to 20nm FWHM (reference)
\begin{itemize}
\item[{$\square$}] Show picture or measurement of the beam size
\end{itemize}
crossed silicon compound refractive lenses, KB mirrors [17], zone plates [18], or multilayer Laue lenses [19]
\cite{barrett16_reflec_optic_hard_x_ray}
\end{itemize}

Higher flux density (+high energy of the ID31 beamline) => Radiation damage: needs to scan the sample quite fast with respect to the focused beam

\begin{itemize}
\item Allowed by better detectors: higher sampling rates and lower noise => possible to scan fast
\cite{hatsui15_x_ray_imagin_detec_synch_xfel_sourc}
\end{itemize}

\paragraph{\ldots{}Requires the use of dynamical positioning}
``from traditional step by step scans to \emph{fly-scan}''

Fast scans + needs of high accuracy and stability => need mechatronics system with:
\begin{itemize}
\item accurate metrology
\item multi degree of freedom positioning systems
\item fast feedback loops
\end{itemize}

Shift from step by step scan to \emph{fly-scan} \cite{huang15_fly_scan_ptych}
\begin{itemize}
\item Much lower pixel size + large image => takes of lot of time if captured step by step.
Explain what is step by step scanning: move motors from point A to point B, stops, start detector acquisition, open shutter , close the shutter, move to point C, \ldots{}
\end{itemize}

\cite{xu23_high_nsls_ii}
\begin{quote}
In traditional step scan mode, each exposure position requires the system to stop prior to data acquisition, which may become a limiting factor when fast data collection is required.
Fly-scanning is chosen as a preferred solution that helps overcome such speed limitations [5, 6].
In fly-scan mode, the sample keeps moving and a triggering system generates trigger signals based on the position of the sample or the time elapsed.
The trigger signals are used to control detector exposure.
\end{quote}

\begin{itemize}
\item[{$\square$}] Make picture representing a typical experiment (maybe YZ scan?) with:
Probably already shown earlier \texttt{introduction\_exp\_scanning}
\begin{itemize}
\item nano focusing optics (see the beam focused)
\item positioning stage with displayed YZ motion (pixel by pixel in the YZ plane)
\item detector
\end{itemize}
\end{itemize}

Subject of this thesis: design of high performance positioning station with high dynamics and nanometer accuracy

\chapter{Challenge definition}
\section{Multi DoF, Highly accurate, and Long stroke positioning end station?}
\paragraph{Performance limitation of ``stacked stages'' end-stations}

Typical positioning end station:
\begin{itemize}
\item stacked stages
\item ballscrew, linear guides, rotary motor
\end{itemize}


Explain the limitation of performances:
\begin{itemize}
\item Backlash, play, thermal expansion, guiding imperfections, \ldots{}
\item Give some numbers: straightness of the Ty stage for instance, change of \(0.1^oC\) with steel gives x nm of motion
\item Vibrations
\item Explain that this micro-station can only have \textasciitilde{}10um of accuracy due to physical limitation
\item Possibility to have linear/rotary encoders that correct the motion in the considered DoF, but does not change anything to the other 5DoF
\end{itemize}


Talk about flexure based positioning stations?
Advantages: no backlash, etc\ldots{}
But: limited to short stroke
Picture of schematic of one positioning station based on flexure

\paragraph{The ID31 Micro-Station}

Presentation of the Micro-Station in details \ref{fig:introduction_id31_microstation_cad}:
\begin{itemize}
\item Goal of each stage (e.g. micro-hexapod: static positioning, Ty and Rz: scans, \ldots{})
\item Stroke
\item Initial design objectives: as stiff as possible, smallest errors as possible
\end{itemize}

\paragraph{New positioning requirements}

\begin{itemize}
\item To benefits from nano-focusing optics, new source, etc\ldots{} new positioning requirements
\item Positioning requirements on ID31:
\begin{itemize}
\item Maybe make a table with the requirements and the associated performances of the micro-station
\item Make tables with the wanted motion, stroke, accuracy in different DoF, etc..
\end{itemize}
\item Sample masses
\end{itemize}

The goal in this thesis is to increase the positioning accuracy of the micro-station to fulfil the initial positioning requirements.

\textbf{Goal}: Improve accuracy of 6DoF long stroke position platform

\section{The Nano Active Stabilization System}
\paragraph{NASS Concept}

Briefly describe the NASS concept.
4 parts:
\begin{itemize}
\item Micro Station
\item multi-DoF positioning system with good dynamics
\item 5DoF metrology system
\item Control system and associated instrumentation
\end{itemize}

6DoF vibration control platform on top of a complex positioning platform that correct positioning errors based on an external metrology

\begin{itemize}
\item[{$\square$}] Add the control system in the schematic
\end{itemize}

\begin{figure}[htbp]
\centering
\includegraphics[scale=1]{figs/introduction_nass_concept_schematic.png}
\caption{\label{fig:introduction_nass_concept_schematic}Nass Concept. 1: micro-station, 2: nano-hexapod, 3: sample, 4: 5DoF metrology}
\end{figure}

\paragraph{Metrology system}

Requirements:
\begin{itemize}
\item 5 DoF
\item long stroke
\item nano-meter accurate
\item high bandwidth
\end{itemize}

The accuracy of the NASS will only depend on the accuracy of the metrology system.

Concept:
\begin{itemize}
\item Fiber interferometers
\item Spherical reflector with flat bottom
\item Tracking system
\end{itemize}

Complex mechatronics system on its own.

This metrology system is not further discussed in this thesis as it is still under active development.

In the following of this thesis, it is supposed that the metrology system is accurate, etc..

\begin{itemize}
\item Say that there are several high precision sensors, but only interferometers for long stroke / high accuracy?
\end{itemize}

\paragraph{Multi-DoF Positioning stage for error compensation}

\begin{itemize}
\item 5 DoF
\item High dynamics
\item nano-meter capable (no backlash,)
\item Accept payloads up to 50kg
\end{itemize}

\paragraph{MIMO robust control strategies}

Explain the robustness need?
\begin{itemize}
\item 24 7/7 \ldots{}
\item That is why most of end-stations are based on well-proven design (stepper motors, linear guides, ball bearing, \ldots{})
\item Plant uncertainty: many different samples, use cases, rotating velocities, etc\ldots{}
\end{itemize}

Trade-off between robustness and performance in the design of feedback system.

\section{Predictive Design}

\begin{itemize}
\item The performances of the system will depend on many factors:
\begin{itemize}
\item sensors
\item actuators
\item mechanical design
\item achievable bandwidth
\item \ldots{}
\end{itemize}
\item Need to evaluate the different concepts, and predict the performances to guide the design
\item The goal is to design, built and test this system such that it work as expected the first time.
Very costly system, so much be correct.
\end{itemize}

\section{Control Challenge}

High bandwidth, 6 DoF system for vibration control, fixed on top of a complex multi DoF positioning station, robust, \ldots{}

\begin{itemize}
\item Many different configurations (tomography, Ty scans, slow fast, \ldots{})
\item Complex MIMO system. Dynamics of the system could be coupled to the complex dynamics of the micro station
\item Rotation aspect, gyroscopic effects, actuators are rotating with respect to the sensors
\item Robustness to payload change: very critical.
Say that high performance systems (lithography machines, etc\ldots{}) works with calibrated payloads.
Being robust to change of payload inertia means large stability margins and therefore less performance.
\end{itemize}

\chapter{Literature Review}
\section{Nano Positioning end-stations}
\paragraph{End Station with Stacked Stages}

Stacked stages:
\begin{itemize}
\item errors are combined
\end{itemize}

To have acceptable performances / stability:
\begin{itemize}
\item limited number of stages
\item high performances stages (air bearing etc\ldots{})
\end{itemize}

Examples:
\begin{itemize}
\item ID16b \cite{martinez-criado16_id16b}
\item ID13 \cite{riekel10_progr_micro_nano_diffr_at}
\item ID11 \cite{wright20_new_oppor_at_mater_scien}
\item ID01 \cite{leake19_nanod_beaml_id01}
\item[{$\square$}] Maybe make a table to compare stations
\end{itemize}

Explain limitations => Thermal drifts, run-out errors of spindles (improved by using air bearing), straightness of translation stages, \ldots{}

\paragraph{Online Metrology and Active Control of Positioning Errors}

The idea of having an external metrology to correct for errors is not new.

\begin{itemize}
\item To have even better performances: online metrology are required.
\item Several strategies:
\begin{itemize}
\item only used for measurements (post processing)
\item for calibration
\item for triggering detectors
\item for real time positioning control
\end{itemize}
\end{itemize}



\begin{itemize}
\item[{$\square$}] HXN \cite{xu23_high_nsls_ii}
Laser interferometers on reference ring (on top of rotary stage).
Used to trigger the detectors (ptychography, microscope)
Similar to \cite{wang12_autom_marker_full_field_hard}
\end{itemize}

\begin{table}[htbp]
\caption{\label{tab:introduction_sample_stages}Table caption}
\centering
\begin{tabularx}{\linewidth}{lllllllX}
\toprule
Architecture & Sensors and measured DoFs & Actuators and controlled DoFs & Institute, BL & OL/CL (bandwidth) & Stroke, DoF & Samples & Ref\\
\midrule
XYZ, Spherical retroreflector, Sample & 3 interferometers\footnotemark, Y,Z & YZ piezo stages & PETRA III, P06 & OL & 100um & light & \cite{schroer17_ptynam,schropp20_ptynam}\\
Spindle / Metrology Ring / XYZ Stage / Sample & 3 Capacitive, Y,Z,Rx &  & NSLS, X8C & OL, post processing &  & micron scale & \cite{wang12_autom_marker_full_field_hard}\\
\textbf{Hexapod} / Spindle / Metrology Ring / Sample & 12 Capacitive\footnotemark, X,Y,Z,Rx,Ry & Piezo (Hexapod) & ESRF, ID16a & CL, 10Hz bandwidth & 50um, 500urad & light & \cite{villar18_nanop_esrf_id16a_nano_imagin_beaml}\\
XYZ, Rz, XY, Cylindrical reference & 5 interferometers\footnotemark, X,Y,Z,Rx,Ry & XYZ linear motors & Soleil & CL &  & light & \cite{engblom18_nanop_resul,stankevic17_inter_charac_rotat_stages_x_ray_nanot}\\
XYZ, Rz, XYZ Spherical reference & 3 Interferometers\footnotemark, Y,Z,Rx & XYZ parallel piezo stage & PSI, OMNY & CL & 400um & light & \cite{holler18_omny_tomog_nano_cryo_stage,holler17_omny_pin_versat_sampl_holder}\\
XYZ, mirrors/sample & 3 interferometers\textsuperscript{\ref{org12e9b3b}}, XYZ & XYZ piezo stage & APS & CL, 3 PID & 3mm & light & \cite{nazaretski15_pushin_limit}\\
Rz, Parallel XYZ stage & 3 interferometers\textsuperscript{\ref{orgd8c7548}} & 3xVCM parallel stage & LNLS, CARNAUBA & CL, 100Hz bandwidth & YZ: 3mm, Rz: +-110deg & light & \cite{geraldes23_sapot_carnaub_sirius_lnls}\\
Parallel XYZ stage & 3 interferometers\textsuperscript{\ref{org65d59ad}}, XYZ & 3xVCM parallel stage & Diamond, I14 & CL, 100Hz bandwidth & XYZ: 3mm & up to 350g & \cite{kelly22_delta_robot_long_travel_nano}\\
\bottomrule
\end{tabularx}
\end{table}\footnotetext[1]{\label{orgd8c7548}PicoScale SmarAct Michelson interferometers}\footnotetext[2]{\label{orgcd87c48}Capacitive sensors from Fogale Sensors}\footnotetext[3]{\label{org12e9b3b}Attocube FPS3010 Fabry-Pérot interferometers}\footnotetext[4]{\label{org65d59ad}Attocube IDS3010 Fabry-Pérot interferometers}

\begin{itemize}
\item[{$\square$}] Figure with different stages
\item[{$\square$}] Compared to the existing stages (see table), what are the challenges here? Rotation, large stroke, light to heavy payloads, lots of DoF (5 to be controlled)
\item[{$\square$}] Comparison with NASS?
\end{itemize}
\begin{center}
\begin{tabular}{llllllll}
Architecture & Sensors & Actuators & Institute, BL & OL/CL (bandwidth) & Stroke, DoF & Samples & Ref\\
\hline
Ty,Ry,Rz,Hexapod,Sample & 6+ Interferometers &  & ESRF, ID31 & CL & Ty, Ry, Rz, Hexa & up to 50kg & \\
\end{tabular}
\end{center}


\paragraph{Long Stroke - Short Stroke architecture}

Speak about two stage control?
\begin{itemize}
\item Long stroke + short stroke
\item Usually applied to 1dof, 3dof (show some examples: disk drive, wafer scanner)
\item Any application in 6DoF? Maybe new!
\item In the table, say which ones are long stroke / short stroke. Some new stages are just long stroke (voice coil)
\end{itemize}

\section{Multi-DoF dynamical positioning stations}
\paragraph{Serial and Parallel Kinematics}

Example of several dynamical stations:
\begin{itemize}
\item XYZ piezo stages
\item Delta robot? Octoglide?
\item Stewart platform
\end{itemize}

Serial vs parallel kinematics (table?)

\paragraph{Stewart platforms}

\begin{itemize}
\item[{$\square$}] Explain the normal stewart platform architecture
\item[{$\square$}] Make a table that compares the different stewart platforms for vibration control.
Geometry (cubic), Actuator (soft, stiff), Sensor, Flexible joints, etc.
\end{itemize}

\begin{figure}
\begin{subfigure}{0.49\textwidth}
\begin{center}
\includegraphics[scale=1,width=0.8\linewidth]{example-image-a.png}
\end{center}
\subcaption{Stewart platform based on voice coil actuators}
\end{subfigure}
\begin{subfigure}{0.49\textwidth}
\begin{center}
\includegraphics[scale=1,width=0.8\linewidth]{example-image-b.png}
\end{center}
\subcaption{Stewart platform based on piezoelectric actuators}
\end{subfigure}
\caption{\label{fig:introduction_stewart_platform_examples}Examples of Stewart Platforms}
\end{figure}

\section{Mechatronics approach}
\paragraph{Predicting performances using models}

\begin{itemize}
\item \cite{monkhorst04_dynam_error_budget}
\begin{quote}
high costs of the design process: the designed system must be \textbf{first time right}.
When the system is finally build, its performance level should satisfy the specifications.
No significant changes are allowed in the post design phase.
Because of this, the designer wants to be able to predict the performance of the system a-priori and gain insight in the performance limiting factors of the system.
\end{quote}
\end{itemize}


Can use several models:
\begin{itemize}
\item Lumped mass-spring-damper models
\cite{rankers98_machin}
\item Multi-Body Models
\item Finite element models
Sub structuring?
\end{itemize}

\paragraph{Closed-Loop Simulations}

\cite{schmidt20_desig_high_perfor_mechat_third_revis_edition}

Say what can limit the performances for a complex mechatronics systems as this one:
\begin{itemize}
\item disturbances
\item measurement noise
\item DAC / amplifier noise (actuator)
\item feedback system / bandwidth
\end{itemize}

Simulations can help evaluate the behavior of the system.

\paragraph{Dynamic Error Budgeting}

\begin{itemize}
\item \cite{monkhorst04_dynam_error_budget}
\begin{quote}
high costs of the design process: the designed system must be \textbf{first time right}.
When the system is finally build, its performance level should satisfy the specifications.
No significant changes are allowed in the post design phase.
Because of this, the designer wants to be able to predict the performance of the system a-priori and gain insight in the performance limiting factors of the system.
\end{quote}
\item \cite{jabben07_mechat}
\item \cite{okyay16_mechat_desig_dynam_contr_metrol}
\begin{quote}
Error budgets [23] are frequently used in the design of precision machines, in order to assess the
contributions of different factors such as parasitic motions, thermal expansion, and servo accuracy, on
the positioning accuracy of a machine. Dynamic Error Budgeting (DEB) or ‘Spectral Analysis’
extends this concept to the realm of feedback control. Recognizing that the controller can provide
only a finite attenuation of disturbance signals interfering with the servo, DEB provides a
methodology for predicting the cumulative effect of such signals on the control error as a function of
their spectral (frequency) content. The method can be used to predict the control accuracy of a system
implemented using a set of certain devices under certain conditions before it is realized. Furthermore,
as it is formulated in the frequency domain, it can be used to optimize the controller design as well,
typically leading to an H2 - optimal control framework. In DEB, the disturbance signals are modeled
with their power spectral density (PSD), assuming that they are stationary stochastic processes which
are not correlated with each other. Then, these PSD’s are transmitted to the performance goal, most
often the positioning error, using linear time invariant (LTI) system theory. The transmitted PSD’s are
summed up into the variance of the performance goal, which constitutes a comparative measure of
performance. Most importantly, the influence of different dynamic factors and disturbance sources,
which have the greatest impact on the achievable performance (e.g., accuracy) can be easily spotted
and improved, through this kind of analysis. An approach similar to DEB was followed to decompose
the contribution of different noise sources on the hard disk position error in [1], [2], [45]. DEB has
been used to assess the performance of a geophone and a vibration isolation system in [75]. Jabben
[49] has used DEB in the mechatronic design of a magnetically suspended rotating platform. Aguirre
et al. [3] have analyzed the performance of active aerostatic thrust bearings using DEB.
\end{quote}
\end{itemize}

\section{Control architecture}

Maybe make a simple review of control strategies for Stewart platform control.
Based on \url{file:///home/thomas/Cloud/work-projects/ID31-NASS/matlab/stewart-simscape/org/bibliography.org}

Broad subject (MIMO control), maybe talk only about vibration control based on external metrology.

\begin{itemize}
\item Active Damping
\item Decentralized
\item Centralized
\item Manually tuned: PID, lead lag, etc\ldots{}
\item Automatic / Optimal: LQG, H-Infinity
\end{itemize}

\chapter{Original Contributions}
This thesis proposes several contributions in the fields of Control, Mechatronics Design and Experimental validation.

\paragraph{Active Damping of rotating mechanical systems using Integral Force Feedback}

\cite{dehaeze20_activ_dampin_rotat_platf_integ_force_feedb,dehaeze21_activ_dampin_rotat_platf_using}
\begin{quote}
This paper investigates the use of Integral Force Feedback (IFF) for the active damping of rotating mechanical systems.
Guaranteed stability, typical benefit of IFF, is lost as soon as the system is rotating due to gyroscopic effects.
To overcome this issue, two modifications of the classical IFF control scheme are proposed.
The first consists of slightly modifying the control law while the second consists of adding springs in parallel with the force sensors.
Conditions for stability and optimal parameters are derived.
The results reveal that, despite their different implementations, both modified IFF control scheme have almost identical damping authority on the suspension modes.
\end{quote}

\paragraph{Design of complementary filters using \(\mathcal{H}_\infty\) Synthesis and sensor fusion}

\cite{dehaeze19_compl_filter_shapin_using_synth}
\cite{verma20_virtual_sensor_fusion_high_precis_contr}
\cite{tsang22_optim_sensor_fusion_method_activ}

\begin{itemize}
\item Several uses (link to some papers).
\item For the NASS, they could be use to further improve the robustness of the system.
\end{itemize}

\paragraph{Multi-body simulations with reduced order flexible bodies obtained by FEA}

\cite{brumund21_multib_simul_reduc_order_flexib_bodies_fea}

Combined multi-body / FEA techniques and experimental validation on a Stewart platform containing amplified piezoelectric actuators
Super-element of amplified piezoelectric actuator / combined multibody-FEA technique, experimental validation on an amplified piezoelectric actuator and further validated on a complete stewart platform

\begin{quote}
We considered sub-components in the multi-body model as \emph{reduced order flexible bodies} representing the component’s modal behaviour with reduced mass and stiffness matrices obtained from finite element analysis (FEA) models.
These matrices were created from FEA models via modal reduction techniques, more specifically the \emph{component mode synthesis} (CMS).
This makes this design approach a combined multibody-FEA technique.
We validated the technique with a test bench that confirmed the good modelling capabilities using reduced order flexible body models obtained from FEA for an amplified piezoelectric actuator (APA).
\end{quote}

\paragraph{Robustness by design}

\begin{itemize}
\item Design of a Stewart platform and associated control architecture that is robust to large plant uncertainties due to large variety of payload and experimental conditions.
\item Instead of relying on complex controller synthesis (such as \(\mathcal{H}_\infty\) synthesis or \(\mu\text{-synthesis}\)) to guarantee the robustness and performance.
\item The approach here is to choose an adequate architecture (mechanics, sensors, actuators) such that controllers are robust by nature.
\item Example: collocated actuator/sensor pair => controller can easily be made robust
\item This is done by using models and using HAC-LAC architecture
\end{itemize}

\paragraph{Mechatronics design}

Conduct a rigorous mechatronics design approach for a nano active stabilization system
\cite{dehaeze18_sampl_stabil_for_tomog_exper,dehaeze21_mechat_approac_devel_nano_activ_stabil_system}

Approach from start to finish:
\begin{itemize}
\item From first concepts using basic models, to concept validation
\item Detailed design phase
\item Experimental phase
\end{itemize}

Complete design with clear choices based on models.
Such approach, while not new, is here applied
This can be used for the design of future end-stations.

\begin{figure}[htbp]
\centering
\includegraphics[scale=1,width=\linewidth]{figs/nass_mechatronics_approach.png}
\caption{\label{fig:introduction_nass_mechatronics_approach}Overview of the mechatronic approach used for the Nano-Active-Stabilization-System}
\end{figure}

\paragraph{6DoF vibration control of a rotating platform}

Vibration control in 5DoF of a rotating stage
To the author's knowledge, the use of a continuously rotating stewart platform for vibration control has not been proved in the literature.

\paragraph{Experimental validation of the Nano Active Stabilization System}

Demonstration of the improvement of the the positioning accuracy of a complex multi DoF (the micro-station) by several orders of magnitude (Section \ldots{}) using \ldots{}

\chapter{Thesis Outline - Mechatronics Design Approach}
\begin{figure}[htbp]
\centering
\includegraphics[scale=1,width=\linewidth]{figs/introduction_overview_chapters.png}
\caption{\label{fig:introduction_overview_chapters}Overview of the sections}
\end{figure}

This thesis
\begin{itemize}
\item has a structure that follows the mechatronics design approach
\end{itemize}

Is structured in three chapters that corresponds to the three mains parts of the proposed mechatronics approach.

A brief overview of these three chapters is given bellow.

\paragraph{Conceptual design development}

\begin{itemize}
\item Start with simple models for witch trade offs can be easily understood (uniaxial)
\item Increase the model complexity if important physical phenomenon are to be modelled (cf the rotating model)
\item Only when better understanding of the physical effects in play, and only if required, go for higher model complexity (here multi-body model)
\item The system concept and main characteristics should be extracted from the different models and validated with closed-loop simulations with the most accurate model
\item Once the concept is validated, the chosen concept can be design in mode details
\end{itemize}

\paragraph{Detailed design}

\begin{itemize}
\item During this detailed design phase, models are refined from the obtained CAD and using FEM
\item The models are used to assists the design and to optimize each element based on dynamical analysis and closed-loop simulations
\item The requirements for all the associated instrumentation can be determined from a dynamical noise budgeting
\item After converging to a detailed design that give acceptable performance based on the models, the different parts can be ordered and the experimental phase begins
\end{itemize}

\paragraph{Experimental validation}

\begin{itemize}
\item It is advised that the important characteristics of the different elements are evaluated individually
Systematic validation/refinement of models with experimental measurements
\item The obtained characteristics can be used to refine the models
\item Then, an accurate model of the system is obtained which can be used during experimental tests (for control synthesis for instance)
\end{itemize}


\printbibliography[heading=bibintoc,title={Bibliography}]
\end{document}