Christophe's review
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@ -331,7 +331,6 @@ It is found that the complex dynamics is due to a misalignment between the flexi
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* Mounting Procedure
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<<sec:test_struts_mounting>>
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** Introduction :ignore:
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A mounting bench was developed to ensure:
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- Good coaxial alignment between the interfaces (cylinders) of the flexible joints.
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@ -340,13 +339,11 @@ A mounting bench was developed to ensure:
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- Precise alignment of the APA with the two flexible joints
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- Reproducible and consistent assembly between all struts
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** Mounting Bench
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A CAD view of the mounting bench is shown in Figure ref:fig:test_struts_mounting_bench_first_concept.
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It consists of a "main frame" (Figure ref:fig:test_struts_mounting_step_0) precisely machined to ensure both correct strut length and strut coaxiality.
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The coaxiality is ensured by good flatness (specified at $20\,\mu m$) between surfaces A and B and between surfaces C and D.
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Such flatness was checked using a Faro arm[fn:1] (see Figure ref:fig:test_struts_check_dimensions_bench) and was found to comply with the requirements.
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The strut length (defined by the distance between the rotation points of the two flexible joints) was ensured by using precisely machines dowel holes.
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Such flatness was checked using a FARO arm[fn:1] (see Figure ref:fig:test_struts_check_dimensions_bench) and was found to comply with the requirements.
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The strut length (defined by the distance between the rotation points of the two flexible joints) was ensured by using precisely machined dowel holes.
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#+name: fig:test_struts_mounting
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@ -413,8 +410,6 @@ These "sleeves" have one dowel groove (that are fitted to the dowel holes shown
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#+end_subfigure
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#+end_figure
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** Mounting Procedure
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The "sleeves" were mounted to the main element as shown in Figure ref:fig:test_struts_mounting_step_0.
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The left sleeve has a thigh fit such that its orientation is fixed (it is roughly aligned horizontally), while the right sleeve has a loose fit such that it can rotate (it will get the same orientation as the fixed one when tightening the screws).
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@ -464,11 +459,10 @@ Thanks to this mounting procedure, the coaxiality and length between the two fle
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:header-args:matlab+: :tangle matlab/test_struts_1_flexible_modes.m
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:END:
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<<sec:test_struts_flexible_modes>>
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** Introduction
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A Finite Element Model[fn:3] of the struts is developed and is used to estimate the flexible modes.
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The inertia of the encoder (estimated at $15\,g$) is considered.
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The two cylindrical interfaces were fixed, and the first three flexible modes were computed.
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The two cylindrical interfaces were fixed (boundary conditions), and the first three flexible modes were computed.
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The mode shapes are displayed in Figure ref:fig:test_struts_mode_shapes: an "X-bending" mode at 189Hz, a "Y-bending" mode at 285Hz and a "Z-torsion" mode at 400Hz.
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#+name: fig:test_struts_mode_shapes
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@ -495,7 +489,6 @@ The mode shapes are displayed in Figure ref:fig:test_struts_mode_shapes: an "X-b
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#+end_subfigure
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#+end_figure
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** Matlab Init :noexport:ignore:
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#+begin_src matlab :tangle no :exports none :results silent :noweb yes :var current_dir=(file-name-directory buffer-file-name)
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<<matlab-dir>>
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#+end_src
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@ -516,8 +509,6 @@ The mode shapes are displayed in Figure ref:fig:test_struts_mode_shapes: an "X-b
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<<m-init-other>>
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#+end_src
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** Measurement Setup
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To experimentally measure these mode shapes, a Laser vibrometer[fn:7] was used.
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It measures the difference of motion between two beam path (red points in Figure ref:fig:test_struts_meas_modes).
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The strut is then excited by an instrumented hammer, and the transfer function from the hammer to the measured rotation is computed.
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@ -550,7 +541,6 @@ These tests were performed with and without the encoder being fixed to the strut
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#+end_subfigure
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#+end_figure
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** Measured results
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The obtained frequency response functions for the three configurations (X-bending, Y-bending and Z-torsion) are shown in Figure ref:fig:test_struts_spur_res_frf_no_enc when the encoder is not fixed to the strut and in Figure ref:fig:test_struts_spur_res_frf_enc when the encoder is fixed to the strut.
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#+begin_src matlab :exports none
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@ -1875,6 +1865,9 @@ exportFig('figs/test_struts_comp_enc_frf_realign.pdf', 'width', 'wide', 'height'
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[[file:figs/test_struts_comp_enc_frf_realign.png]]
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* Conclusion
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:PROPERTIES:
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:UNNUMBERED: t
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:END:
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<<sec:test_struts_conclusion>>
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The Hano-Hexapod struts are a key component of the developed acrfull:nass.
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@ -2294,4 +2287,4 @@ actuator.cs = args.cs; % Damping of one stack [N/m]
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[fn:4] Two fiber intereferometers were used: an IDS3010 from Attocube and a quDIS from QuTools
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[fn:3] Using Ansys\textsuperscript{\textregistered}. Flexible Joints and APA Shell are made of a stainless steel allow called /17-4 PH/. Encoder and ruler support material is aluminium.
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[fn:2] Heidenhain MT25, specified accuracy of $\pm 0.5\,\mu m$
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[fn:1] Faro Arm Platinum 4ft, specified accuracy of $\pm 13\mu m$
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[fn:1] FARO Arm Platinum 4ft, specified accuracy of $\pm 13\mu m$
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Binary file not shown.
@ -1,4 +1,4 @@
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% Created 2024-10-25 Fri 17:22
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% Created 2024-11-18 Mon 10:26
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% Intended LaTeX compiler: pdflatex
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\documentclass[a4paper, 10pt, DIV=12, parskip=full, bibliography=totoc]{scrreprt}
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@ -53,6 +53,7 @@ It is found that the complex dynamics is due to a misalignment between the flexi
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\chapter{Mounting Procedure}
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\label{sec:test_struts_mounting}
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A mounting bench was developed to ensure:
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\begin{itemize}
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\item Good coaxial alignment between the interfaces (cylinders) of the flexible joints.
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@ -61,13 +62,12 @@ This is important not to loose to much angular stroke during their mounting into
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\item Precise alignment of the APA with the two flexible joints
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\item Reproducible and consistent assembly between all struts
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\end{itemize}
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\section{Mounting Bench}
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A CAD view of the mounting bench is shown in Figure \ref{fig:test_struts_mounting_bench_first_concept}.
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It consists of a ``main frame'' (Figure \ref{fig:test_struts_mounting_step_0}) precisely machined to ensure both correct strut length and strut coaxiality.
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The coaxiality is ensured by good flatness (specified at \(20\,\mu m\)) between surfaces A and B and between surfaces C and D.
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Such flatness was checked using a Faro arm\footnote{Faro Arm Platinum 4ft, specified accuracy of \(\pm 13\mu m\)} (see Figure \ref{fig:test_struts_check_dimensions_bench}) and was found to comply with the requirements.
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The strut length (defined by the distance between the rotation points of the two flexible joints) was ensured by using precisely machines dowel holes.
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Such flatness was checked using a FARO arm\footnote{FARO Arm Platinum 4ft, specified accuracy of \(\pm 13\mu m\)} (see Figure \ref{fig:test_struts_check_dimensions_bench}) and was found to comply with the requirements.
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The strut length (defined by the distance between the rotation points of the two flexible joints) was ensured by using precisely machined dowel holes.
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\begin{figure}[htbp]
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@ -128,8 +128,6 @@ These ``sleeves'' have one dowel groove (that are fitted to the dowel holes show
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\caption{\label{fig:test_struts_cylindrical_mounting}Preparation of the flexible joints by fixing them in their cylindrical ``sleeve''}
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\end{figure}
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\section{Mounting Procedure}
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The ``sleeves'' were mounted to the main element as shown in Figure \ref{fig:test_struts_mounting_step_0}.
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The left sleeve has a thigh fit such that its orientation is fixed (it is roughly aligned horizontally), while the right sleeve has a loose fit such that it can rotate (it will get the same orientation as the fixed one when tightening the screws).
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@ -174,11 +172,10 @@ Thanks to this mounting procedure, the coaxiality and length between the two fle
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\chapter{Measurement of flexible modes}
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\label{sec:test_struts_flexible_modes}
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\section{Introduction}
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A Finite Element Model\footnote{Using Ansys\textsuperscript{\textregistered}. Flexible Joints and APA Shell are made of a stainless steel allow called \emph{17-4 PH}. Encoder and ruler support material is aluminium.} of the struts is developed and is used to estimate the flexible modes.
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The inertia of the encoder (estimated at \(15\,g\)) is considered.
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The two cylindrical interfaces were fixed, and the first three flexible modes were computed.
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The two cylindrical interfaces were fixed (boundary conditions), and the first three flexible modes were computed.
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The mode shapes are displayed in Figure \ref{fig:test_struts_mode_shapes}: an ``X-bending'' mode at 189Hz, a ``Y-bending'' mode at 285Hz and a ``Z-torsion'' mode at 400Hz.
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\begin{figure}[htbp]
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@ -203,8 +200,6 @@ The mode shapes are displayed in Figure \ref{fig:test_struts_mode_shapes}: an ``
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\caption{\label{fig:test_struts_mode_shapes}Spurious resonances of the struts estimated from a Finite Element Model}
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\end{figure}
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\section{Measurement Setup}
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To experimentally measure these mode shapes, a Laser vibrometer\footnote{OFV-3001 controller and OFV512 sensor head from Polytec} was used.
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It measures the difference of motion between two beam path (red points in Figure \ref{fig:test_struts_meas_modes}).
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The strut is then excited by an instrumented hammer, and the transfer function from the hammer to the measured rotation is computed.
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@ -235,7 +230,6 @@ These tests were performed with and without the encoder being fixed to the strut
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\caption{\label{fig:test_struts_meas_modes}Measurement of strut flexible modes}
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\end{figure}
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\section{Measured results}
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The obtained frequency response functions for the three configurations (X-bending, Y-bending and Z-torsion) are shown in Figure \ref{fig:test_struts_spur_res_frf_no_enc} when the encoder is not fixed to the strut and in Figure \ref{fig:test_struts_spur_res_frf_enc} when the encoder is fixed to the strut.
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\begin{figure}[htbp]
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@ -589,7 +583,7 @@ Therefore, fixing the encoders to the nano-hexapod plates instead may be an inte
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\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}
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\end{figure}
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\chapter{Conclusion}
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\chapter*{Conclusion}
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\label{sec:test_struts_conclusion}
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The Hano-Hexapod struts are a key component of the developed \acrfull{nass}.
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