diff --git a/test-bench-struts.org b/test-bench-struts.org index d75d6b9..644885f 100644 --- a/test-bench-struts.org +++ b/test-bench-struts.org @@ -297,7 +297,7 @@ Using this method, an axial stiffness of $70 N/\mu m$ is found to give good resu * Introduction :ignore: -The Nano-Hexapod struts (shown in Figure ref:fig:test_struts_picture_strut) are composed of two flexible joints that are fixed at the two ends of the strut, one acrfull:apa[fn:test_struts_5] and one optical encoder[fn:test_struts_6]. +The Nano-Hexapod struts (shown in Figure ref:fig:test_struts_picture_strut) are composed of two flexible joints that are fixed at the two ends of the strut, one Amplified Piezeolectric Actuator [fn:test_struts_5] and one optical encoder[fn:test_struts_6]. #+name: fig:test_struts_picture_strut #+caption: One strut including two flexible joints, an amplified piezoelectric actuator and an encoder @@ -319,16 +319,6 @@ The model dynamics from the acrshort:dac voltage to the axial motion of the stru However, this is not the case for the dynamics from acrshort:dac voltage to the encoder displacement. It is found that the complex dynamics is due to a misalignment between the flexible joints and the acrshort:apa. -# #+name: tab:test_struts_section_matlab_code -# #+caption: Report sections and corresponding Matlab files -# #+attr_latex: :environment tabularx :width 0.6\linewidth :align lX -# #+attr_latex: :center t :booktabs t -# | *Sections* | *Matlab File* | -# |--------------------------------------------+----------------------------------| -# | Section ref:sec:test_struts_flexible_modes | =test_struts_1_flexible_modes.m= | -# | Section ref:sec:test_struts_dynamical_meas | =test_struts_2_dynamical_meas.m= | -# | Section ref:sec:test_struts_simscape | =test_struts_3_simscape_model’m= | - * Mounting Procedure <> diff --git a/test-bench-struts.pdf b/test-bench-struts.pdf index 687cfd7..8bf8c91 100644 Binary files a/test-bench-struts.pdf and b/test-bench-struts.pdf differ diff --git a/test-bench-struts.tex b/test-bench-struts.tex index 586e3ad..82ae1ce 100644 --- a/test-bench-struts.tex +++ b/test-bench-struts.tex @@ -1,4 +1,4 @@ -% Created 2024-11-18 Mon 13:05 +% Created 2025-04-03 Thu 22:09 % Intended LaTeX compiler: pdflatex \documentclass[a4paper, 10pt, DIV=12, parskip=full, bibliography=totoc]{scrreprt} @@ -11,13 +11,6 @@ \author{Dehaeze Thomas} \date{\today} \title{Test Bench - Nano-Hexapod Struts} -\hypersetup{ - pdfauthor={Dehaeze Thomas}, - pdftitle={Test Bench - Nano-Hexapod Struts}, - pdfkeywords={}, - pdfsubject={}, - pdfcreator={Emacs 29.4 (Org mode 9.6)}, - pdflang={English}} \usepackage{biblatex} \begin{document} @@ -26,8 +19,7 @@ \tableofcontents \clearpage - -The Nano-Hexapod struts (shown in Figure \ref{fig:test_struts_picture_strut}) are composed of two flexible joints that are fixed at the two ends of the strut, one \acrfull{apa}\footnote{APA300ML from Cedrat Technologies} and one optical encoder\footnote{Vionic from Renishaw}. +The Nano-Hexapod struts (shown in Figure \ref{fig:test_struts_picture_strut}) are composed of two flexible joints that are fixed at the two ends of the strut, one Amplified Piezeolectric Actuator \footnote{APA300ML from Cedrat Technologies} and one optical encoder\footnote{Vionic from Renishaw}. \begin{figure}[htbp] \centering @@ -49,8 +41,6 @@ The strut models were then compared with the measured dynamics (Section \ref{sec The model dynamics from the \acrshort{dac} voltage to the axial motion of the strut (measured by an interferometer) and to the force sensor voltage well match the experimental results. However, this is not the case for the dynamics from \acrshort{dac} voltage to the encoder displacement. It is found that the complex dynamics is due to a misalignment between the flexible joints and the \acrshort{apa}. - - \chapter{Mounting Procedure} \label{sec:test_struts_mounting} @@ -169,7 +159,6 @@ Thanks to this mounting procedure, the coaxiality and length between the two fle \end{subfigure} \caption{\label{fig:test_struts_mounting_steps}Steps for mounting the struts.} \end{figure} - \chapter{Measurement of flexible modes} \label{sec:test_struts_flexible_modes} @@ -267,7 +256,6 @@ Z-Torsion & 400Hz & 381Hz & 398Hz\\ \caption{\label{tab:test_struts_spur_mode_freqs}Measured frequency of the flexible modes of the strut} \end{table} - \chapter{Dynamical measurements} \label{sec:test_struts_dynamical_meas} In order to measure the dynamics of the strut, the test bench used to measure the APA300ML dynamics is being used again. @@ -343,7 +331,6 @@ This means that the encoder should have little effect on the effectiveness of th \end{subfigure} \caption{\label{fig:test_struts_effect_encoder}Effect of having the encoder fixed to the struts on the measured dynamics from \(u\) to \(d_a\) (\subref{fig:test_struts_effect_encoder_int}) and from \(u\) to \(V_s\) (\subref{fig:test_struts_effect_encoder_iff}). Comparison of the observed dynamics by the encoder and interferometers (\subref{fig:test_struts_comp_enc_int})} \end{figure} - \section{Comparison of the encoder and interferometer} \label{ssec:test_struts_comp_enc_int} @@ -354,7 +341,6 @@ These resonance frequencies match the frequencies of the flexible modes studied The good news is that these resonances are not impacting the axial motion of the strut (which is what is important for the hexapod positioning). However, these resonances make the use of an encoder fixed to the strut difficult from a control perspective. - \section{Comparison of all the Struts} \label{ssec:test_struts_comp_all_struts} @@ -389,7 +375,6 @@ In this study, large dynamics differences were observed between the 5 struts. Although the same resonance frequencies were seen for all of the struts (95Hz, 200Hz, 300Hz and 400Hz), the amplitude of the peaks were not the same. In addition, the location or even presence of complex conjugate zeros changes from one strut to another. The reason for this variability will be studied in the next section thanks to the strut model. - \chapter{Strut Model} \label{sec:test_struts_simscape} The multi-body model of the strut was included in the multi-body model of the test bench (see Figure \ref{fig:test_struts_simscape_model}). @@ -440,7 +425,6 @@ For the flexible model, it will be shown in the next section that by adding some \end{subfigure} \caption{\label{fig:test_struts_comp_frf_flexible_model}Comparison of the measured frequency response functions, the multi-body model using the 2 DoF APA model, and using the ``flexible'' APA300ML model (Super-Element extracted from a Finite Element Model).} \end{figure} - \section{Effect of strut misalignment} \label{ssec:test_struts_effect_misalignment} @@ -490,7 +474,6 @@ This similarity suggests that the identified differences in dynamics are caused \end{subfigure} \caption{\label{fig:test_struts_effect_misalignment}Effect of a misalignment between the flexible joints and the APA300ML in the \(y\) direction (\subref{fig:test_struts_effect_misalignment_y}) and in the \(x\) direction (\subref{fig:test_struts_effect_misalignment_x})} \end{figure} - \section{Measured strut misalignment} \label{ssec:test_struts_meas_misalignment} @@ -540,7 +523,6 @@ With a better alignment, the amplitude of the spurious resonances is expected to \includegraphics[scale=1]{figs/test_struts_comp_dy_tuned_model_frf_enc.png} \caption{\label{fig:test_struts_comp_dy_tuned_model_frf_enc}Comparison of the frequency response functions from DAC voltage \(u\) to measured displacement \(d_e\) by the encoders for the three struts. In blue, the measured dynamics is represted, in red the dynamics extracted from the model with the \(y\) misalignment estimated from measurements, and in yellow, the dynamics extracted from the model when both the \(x\) and \(y\) misalignments are tuned} \end{figure} - \section{Proper struts alignment} \label{sec:test_struts_meas_all_aligned_struts} @@ -581,7 +563,6 @@ Therefore, fixing the encoders to the nano-hexapod plates instead may be an inte \includegraphics[scale=1]{figs/test_struts_comp_enc_frf_realign.png} \caption{\label{fig:test_struts_comp_enc_frf_realign}Comparison of the dynamics from \(u\) to \(d_e\) before and after proper alignment using the dowel pins} \end{figure} - \chapter*{Conclusion} \label{sec:test_struts_conclusion} @@ -593,6 +574,5 @@ Thanks to a \acrshort{fem} and experimental measurements, the modes inducing thi The variability in the dynamics was attributed to the poor alignment of the \acrshort{apa} with respect to the flexible joints. Even with better alignment using dowel pins, the observed dynamics by the encoder remained problematic. Therefore, the encoders will be fixed directly to the nano-hexapod plates rather than being fixed to the struts. - \printglossaries \end{document}