% Created 2025-04-21 Mon 16:49 % Intended LaTeX compiler: pdflatex \documentclass[a4paper, 10pt, DIV=12, parskip=full, bibliography=totoc]{scrreprt} \input{preamble.tex} \input{preamble_extra.tex} \bibliography{nass-design.bib} \author{Dehaeze Thomas} \date{\today} \title{Nano Hexapod - Obtained Design} \hypersetup{ pdfauthor={Dehaeze Thomas}, pdftitle={Nano Hexapod - Obtained Design}, pdfkeywords={}, pdfsubject={}, pdfcreator={Emacs 30.1 (Org mode 9.7.26)}, pdflang={English}} \usepackage{biblatex} \begin{document} \maketitle \tableofcontents \clearpage \begin{figure}[htbp] \centering \includegraphics[scale=1,width=0.95\linewidth]{figs/detail_design_nano_hexapod_elements.png} \caption{\label{fig:detail_design_nano_hexapod_elements}Obtained mechanical design of the Active platform, the ``nano-hexapod''} \end{figure} \textbf{Design goals}: \begin{itemize} \item Position \texttt{bi} and \texttt{si} \item Maximum height of 95mm \item As close as possible to ``perfect'' stewart platform: flexible modes at high frequency \item Easy mounting, easy change of strut in case of failure \end{itemize} Presentation of the obtained design: \begin{itemize} \item Fixation \item Section on: Complete strut \item Cable management \item Plates design \item FEM results \item Explain again the different specifications in terms of space, payload, etc.. \item CAD view of the nano-hexapod \item Chosen geometry, materials, ease of mounting, cabling, \ldots{} \item Validation on Simscape with accurate model? \end{itemize} \chapter{Mechanical Design} \label{sec:detail_design_mechanics} \section{Struts} \begin{figure}[htbp] \begin{subfigure}{0.49\textwidth} \begin{center} \includegraphics[scale=1,width=0.95\linewidth]{figs/detail_design_strut_without_enc.jpg} \end{center} \subcaption{\label{fig:detail_design_strut_without_enc}Before encoder integration} \end{subfigure} \begin{subfigure}{0.49\textwidth} \begin{center} \includegraphics[scale=1,width=0.95\linewidth]{figs/detail_design_strut_with_enc.jpg} \end{center} \subcaption{\label{fig:detail_design_strut_with_enc}With the mounted encoder} \end{subfigure} \caption{\label{fig:detail_design_strut}Design of the Nano-Hexapod struts. Before (\subref{fig:detail_design_strut_without_enc}) and after (\subref{fig:detail_design_strut_with_enc}) encoder integration.} \end{figure} \subsubsection{Flexible joints} Flexible joints: X5CrNiCuNb16-4 (F16Ph) \begin{itemize} \item high yield strength: specified >1GPa using heat treatment \item high fatigue resistance \end{itemize} \begin{figure}[htbp] \begin{subfigure}{0.49\textwidth} \begin{center} \includegraphics[scale=1,scale=1]{figs/detail_design_apa.png} \end{center} \subcaption{\label{fig:detail_design_apa}Amplified Piezoelectric Actuator} \end{subfigure} \begin{subfigure}{0.49\textwidth} \begin{center} \includegraphics[scale=1,scale=1]{figs/detail_design_flexible_joint.png} \end{center} \subcaption{\label{fig:detail_design_flexible_joint}Flexible joint} \end{subfigure} \caption{\label{fig:detail_design_apa_joints}Two main components of the struts: the amplified piezoelectric actuator (\subref{fig:detail_design_apa}) and the flexible joint (\subref{fig:detail_design_flexible_joint}).} \end{figure} \subsubsection{Piezoelectric Amplified Actuators} APA: modification for better mounting \subsubsection{Encoder support} All other parts are made of aluminum. \section{Plates} Plates: X30Cr13 \begin{itemize} \item high hardness to not deform \end{itemize} \begin{itemize} \item Maximize frequency of flexible modes (show FEM) \item Good tolerances for interfaces with flexible joints Positioning of \texttt{bi} and orientation \texttt{si} \end{itemize} \begin{figure}[htbp] \centering \includegraphics[scale=1,scale=1]{figs/detail_design_top_plate.png} \caption{\label{fig:detail_design_top_plate}The mechanical design for the top platform incorporates precisely positioned V-grooves for the joint interfaces (displayed in red). The purpose of the encoder interface (shown in green) is detailed later.} \end{figure} The cylindrical component is located (or constrained) within the V-groove via two distinct line contacts. \begin{figure} \begin{subfigure}{0.33\textwidth} \begin{center} \includegraphics[scale=1,width=0.99\linewidth]{figs/detail_design_fixation_flexible_joints.png} \end{center} \subcaption{\label{fig:detail_design_fixation_flexible_joints}Flexible Joint Clamping} \end{subfigure} \begin{subfigure}{0.33\textwidth} \begin{center} \includegraphics[scale=1,width=0.99\linewidth]{figs/detail_design_location_top_flexible_joints.png} \end{center} \subcaption{\label{fig:detail_design_location_top_flexible_joints}Top positioning} \end{subfigure} \begin{subfigure}{0.33\textwidth} \begin{center} \includegraphics[scale=1,width=0.99\linewidth]{figs/detail_design_location_bot_flex.png} \end{center} \subcaption{\label{fig:detail_design_location_bot_flex}Bottom Positioning} \end{subfigure} \caption{\label{fig:detail_design_fixation_flexible_joints}Fixation of the flexible points to the nano-hexapod plates. Both top and bottom flexible joints are clamped to the plates as shown in (\subref{fig:detail_design_fixation_flexible_joints}). While the top flexible joint is in contact with the top plate for precise positioning of its center of rotation (\subref{fig:detail_design_location_top_flexible_joints}), the bottom joint is just oriented (\subref{fig:detail_design_location_bot_flex}).} \end{figure} \section{Finite Element Analysis} \begin{figure}[htbp] \centering \includegraphics[scale=1,width=0.9\linewidth]{figs/detail_design_enc_struts.jpg} \caption{\label{fig:detail_design_enc_struts}Obtained Nano-Hexapod design} \end{figure} \begin{itemize} \item FEM of complete system \item Show modes of the struts \end{itemize} \begin{figure}[htbp] \begin{subfigure}{0.33\textwidth} \begin{center} \includegraphics[scale=1,width=0.9\linewidth]{figs/detail_design_fem_rigid_body_mode.jpg} \end{center} \subcaption{\label{fig:detail_design_fem_rigid_body_mode}Suspension modes} \end{subfigure} \begin{subfigure}{0.33\textwidth} \begin{center} \includegraphics[scale=1,width=0.9\linewidth]{figs/detail_design_fem_strut_mode.jpg} \end{center} \subcaption{\label{fig:detail_design_fem_strut_mode}Strut - Local modes} \end{subfigure} \begin{subfigure}{0.33\textwidth} \begin{center} \includegraphics[scale=1,width=0.9\linewidth]{figs/detail_design_fem_plate_mode.jpg} \end{center} \subcaption{\label{fig:detail_design_fem_plate_mode}Top plate modes} \end{subfigure} \caption{\label{fig:detail_design_fem_nano_hexapod}Measurement of strut flexible modes. First six modes are ``suspension'' modes in which the top plate behaves as a rigid body (\subref{fig:detail_design_fem_rigid_body_mode}). Then modes of the struts have natural frequencies from \(205\,\text{Hz}\) to \(420\,\text{Hz}\) (\subref{fig:detail_design_fem_strut_mode}). Finally, the first flexible mode of the top plate is at \(650\,\text{Hz}\) (\subref{fig:detail_design_fem_plate_mode})} \end{figure} \section{Obtained Design} \begin{itemize} \item Alternative encoder position: on the plates \item Support made of aluminum \end{itemize} \begin{figure}[htbp] \begin{subfigure}{0.59\textwidth} \begin{center} \includegraphics[scale=1,height=5cm]{figs/detail_design_enc_plates.jpg} \end{center} \subcaption{\label{fig:detail_design_enc_plates}Nano-Hexapod with encoders fixed to the plates} \end{subfigure} \begin{subfigure}{0.39\textwidth} \begin{center} \includegraphics[scale=1,height=5cm]{figs/detail_design_encoders_plates.jpg} \end{center} \subcaption{\label{fig:detail_design_encoders_plates}Zoom on encoder fixation} \end{subfigure} \caption{\label{fig:detail_design_enc_plates_design}Alternative way of using the encoders: they are fixed directly to the plates.} \end{figure} \begin{figure}[htbp] \centering \includegraphics[scale=1]{figs/detail_design_fem_encoder_fix.png} \caption{\label{fig:detail_design_fem_encoder_fix}Finite Element Analysis of the encoder supports. Encoder inertia was taken into account.} \end{figure} \chapter{Multi-Body Model} \label{sec:detail_design_model} \textbf{Multi body Model}: \begin{itemize} \item Complete model: two plates, 6 joints, 6 actuators, 6 encoders \item Joint Model \item APA Model \item Encoder model \item Say that obtained dynamics was considered good + possible to perform simulations of tomography experiments with same performance as during the conceptual design \end{itemize} Two configurations: \begin{itemize} \item Encoders fixed to the struts \item Encoders fixed to the plates \end{itemize} \begin{figure}[htbp] \begin{subfigure}{0.49\textwidth} \begin{center} \includegraphics[scale=1,width=0.95\linewidth]{figs/detail_design_simscape_encoder_struts.png} \end{center} \subcaption{\label{fig:detail_design_simscape_encoder_struts}Encoders fixed to the struts} \end{subfigure} \begin{subfigure}{0.49\textwidth} \begin{center} \includegraphics[scale=1,width=0.95\linewidth]{figs/detail_design_simscape_encoder_plates.png} \end{center} \subcaption{\label{fig:detail_design_simscape_encoder_plates}Encoders fixed to the plates} \end{subfigure} \caption{\label{fig:detail_design_simscape_encoder}3D representation of the multi-body model. There are two configurations: encoders fixed to the struts (\subref{fig:detail_design_simscape_encoder_struts}) and encoders fixed to the plates (\subref{fig:detail_design_simscape_encoder_plates}).} \end{figure} \section{Flexible Joints} \begin{figure}[htbp] \centering \includegraphics[scale=1,scale=1]{figs/detail_design_simscape_model_flexible_joint.png} \caption{\label{fig:detail_design_simscape_model_flexible_joint}Multi-Body (using the Simscape software) model of the flexible joints. A 4-DoFs model is shown.} \end{figure} \section{Amplified Piezoelectric Actuators} \section{Encoders} \begin{figure}[htbp] \begin{subfigure}{0.49\textwidth} \begin{center} \includegraphics[scale=1,scale=1]{figs/detail_design_simscape_encoder.png} \end{center} \subcaption{\label{fig:detail_design_simscape_encoder}Aligned encoder and ruler} \end{subfigure} \begin{subfigure}{0.49\textwidth} \begin{center} \includegraphics[scale=1,scale=1]{figs/detail_design_simscape_encoder_disp.png} \end{center} \subcaption{\label{fig:detail_design_simscape_encoder_disp}Rotation of the encoder head} \end{subfigure} \caption{\label{fig:detail_design_simscape_encoder_model}Representation of the encoder model in the multi-body model. Measurement \(d_i\) corresponds to the \(x\) position of the encoder frame \(\{E\}\) expresssed in the ruller frame \(\{R\}\) (\subref{fig:detail_design_simscape_encoder}). A rotation of the encoder therefore induces a measured displacement (\subref{fig:detail_design_simscape_encoder_disp}).} \end{figure} \chapter{Conclusion} \label{sec:detail_design_conclusion} \printbibliography[heading=bibintoc,title={Bibliography}] \end{document}