Rename footnotes
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@ -507,7 +507,7 @@ As the long-stroke ($\approx 1 \,cm^3$) metrology system was not developed yet,
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A first considered option was to use the "Spindle error analyzer" shown in Figure ref:fig:test_id31_lion.
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This system comprises 5 capacitive sensors which are facing two reference spheres.
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But as the gap between the capacitive sensors and the spheres is very small[fn:1], the risk of damaging the spheres and the capacitive sensors is too high.
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But as the gap between the capacitive sensors and the spheres is very small[fn:test_id31_1], the risk of damaging the spheres and the capacitive sensors is too high.
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#+name: fig:test_id31_short_stroke_metrology
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#+caption: Short stroke metrology system used to measure the sample position with respect to the granite in 5DoF. The system is based on a "Spindle error analyzer" (\subref{fig:test_id31_lion}), but the capacitive sensors are replaced with fibered interferometers (\subref{fig:test_id31_interf}). Interferometer heads are shown in (\subref{fig:test_id31_interf_head})
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@ -534,7 +534,7 @@ But as the gap between the capacitive sensors and the spheres is very small[fn:1
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#+end_figure
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Instead of using capacitive sensors, 5 fibered interferometers were used in a similar way (Figure ref:fig:test_id31_interf).
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At the end of each fiber, a sensor head[fn:2] (Figure ref:fig:test_id31_interf_head) is used, which consists of a lens precisely positioned with respect to the fiber's end.
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At the end of each fiber, a sensor head[fn:test_id31_2] (Figure ref:fig:test_id31_interf_head) is used, which consists of a lens precisely positioned with respect to the fiber's end.
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The lens is focusing the light on the surface of the sphere, such that the reflected light comes back into the fiber and produces an interference.
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This way, the gap between the head and the reference sphere is much larger (here around $40\,mm$), removing the risk of collision.
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@ -860,7 +860,7 @@ First, the "metrology kinematics" (discussed in Section ref:ssec:test_id31_metro
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This can be easily seen when performing lateral $[D_x,\,D_y]$ scans using the micro-hexapod while recording the vertical interferometer (Figure ref:fig:test_id31_xy_map_sphere).
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As the interferometer is pointing to a sphere and not to a plane, lateral motion of the sphere is seen as a vertical motion by the top interferometer.
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Then, the reference spheres have some deviations with respect to an ideal sphere [fn:6].
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Then, the reference spheres have some deviations with respect to an ideal sphere [fn:test_id31_6].
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They are initially meant to be used with capacitive sensors which are integrating the shape errors over large surfaces.
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When using interferometers, the size of the "light spot" on the sphere surface is a circle with a diameter approximately equal to $50\,\mu m$, and therefore the measurement is more sensitive to shape errors with small features.
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@ -1081,7 +1081,7 @@ A good match can be observed for the diagonal dynamics (except the high frequenc
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However, the coupling for the transfer function from command signals $\bm{u}$ to the estimated strut motion from the external metrology $\bm{\epsilon\mathcal{L}}$ is larger than expected (Figure ref:fig:test_id31_first_id_int).
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The experimental time delay estimated from the FRF (Figure ref:fig:test_id31_first_id_int) is larger than expected.
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After investigation, it was found that the additional delay was due to a digital processing unit[fn:3] that was used to get the interferometers' signals in the Speedgoat.
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After investigation, it was found that the additional delay was due to a digital processing unit[fn:test_id31_3] that was used to get the interferometers' signals in the Speedgoat.
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This issue was later solved.
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#+begin_src matlab
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@ -3218,7 +3218,7 @@ exportFig('figs/test_id31_hac_characteristic_loci.pdf', 'width', 'half', 'height
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** Performance estimation with simulation of Tomography scans
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<<ssec:test_id31_iff_hac_perf>>
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To estimate the performances that can be expected with this HAC-LAC architecture and the designed controller, simulations of tomography experiments were performed[fn:4].
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To estimate the performances that can be expected with this HAC-LAC architecture and the designed controller, simulations of tomography experiments were performed[fn:test_id31_4].
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The rotational velocity was set to $180\,\text{deg/s}$, and no payload was added on top of the nano-hexapod.
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An open-loop simulation and a closed-loop simulation were performed and compared in Figure ref:fig:test_id31_tomo_m0_30rpm_robust_hac_iff_sim.
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The obtained closed-loop positioning accuracy was found to comply with the requirements as it succeeded to keep the point of interest on the beam (Figure ref:fig:test_id31_tomo_m0_30rpm_robust_hac_iff_sim_yz).
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@ -3815,7 +3815,7 @@ data_tomo_m3_Wz6.Ry_rms_ol = rms(data_tomo_m3_Wz6.Ry_int(1:i_m3) - (y0 + R*sin(d
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**** Fast Tomography scans
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A tomography experiment was then performed with the highest rotational velocity of the Spindle: $180\,\text{deg/s}$[fn:7].
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A tomography experiment was then performed with the highest rotational velocity of the Spindle: $180\,\text{deg/s}$[fn:test_id31_7].
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The trajectory of the point of interest during this fast tomography scan is shown in Figure ref:fig:test_id31_tomo_m0_30rpm_robust_hac_iff_exp.
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While the experimental results closely mirror the simulation results (Figure ref:fig:test_id31_tomo_m0_30rpm_robust_hac_iff_sim), the actual performance are slightly lower than predicted.
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Nevertheless, even with this robust (conservative) HAC implementation, the system performance approaches the specified requirements.
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@ -4455,7 +4455,7 @@ exportFig('figs/test_id31_dz_scan_10ums_ry.pdf', 'width', 'third', 'height', 'no
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#+end_subfigure
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#+end_figure
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A subsequent scan at $100,\mu m/s$ - the maximum velocity for high-precision $D_z$ scans[fn:8] - maintains positioning errors within specifications during the constant velocity phase, with deviations occurring only during acceleration and deceleration phases (Figure ref:fig:test_id31_dz_scan_100ums).
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A subsequent scan at $100,\mu m/s$ - the maximum velocity for high-precision $D_z$ scans[fn:test_id31_8] - maintains positioning errors within specifications during the constant velocity phase, with deviations occurring only during acceleration and deceleration phases (Figure ref:fig:test_id31_dz_scan_100ums).
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Since detectors typically operate only during the constant velocity phase, these transient deviations do not compromise measurement quality.
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Yet, performance during acceleration phases could potentially be enhanced through the implementation of feedforward control.
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@ -4555,7 +4555,7 @@ exportFig('figs/test_id31_dz_scan_100ums_ry.pdf', 'width', 'third', 'height', 'n
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**** Introduction :ignore:
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Lateral scans are executed using the $T_y$ stage.
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The stepper motor controller[fn:5] generates a setpoint that is transmitted to the Speedgoat.
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The stepper motor controller[fn:test_id31_5] generates a setpoint that is transmitted to the Speedgoat.
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Within the Speedgoat, the system computes the positioning error by comparing the measured $D_y$ sample position against the received setpoint, and the Nano-Hexapod compensates for positioning errors introduced during $T_y$ stage scanning.
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The scanning range is constrained $\pm 100\,\mu m$ due to the limited acceptance of the metrology system.
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@ -7599,11 +7599,11 @@ function [stewart] = initializeStewartPlatform()
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* Footnotes
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[fn:8]Such scan could corresponding to a 1ms integration time (which is typically the smallest integration time) and 100nm "resolution" (equal to the vertical beam size).
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[fn:7]The highest rotational velocity of $360\,\text{deg/s}$ could not be tested due to an issue in the Spindle's controller.
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[fn:6]The roundness of the spheres is specified at $50\,nm$.
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[fn:5]The "IcePAP" [[cite:&janvier13_icepap]] which is developed at the ESRF.
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[fn:4]Note that the eccentricity of the "point of interest" with respect to the Spindle rotation axis has been tuned based on measurements.
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[fn:3]The "PEPU" [[cite:&hino18_posit_encod_proces_unit]] was used for digital protocol conversion between the interferometers and the Speedgoat.
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[fn:2]M12/F40 model from Attocube.
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[fn:1]Depending on the measuring range, gap can range from $\approx 1\,\mu m$ to $\approx 100\,\mu m$.
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[fn:test_id31_8]Such scan could corresponding to a 1ms integration time (which is typically the smallest integration time) and 100nm "resolution" (equal to the vertical beam size).
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[fn:test_id31_7]The highest rotational velocity of $360\,\text{deg/s}$ could not be tested due to an issue in the Spindle's controller.
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[fn:test_id31_6]The roundness of the spheres is specified at $50\,nm$.
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[fn:test_id31_5]The "IcePAP" [[cite:&janvier13_icepap]] which is developed at the ESRF.
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[fn:test_id31_4]Note that the eccentricity of the "point of interest" with respect to the Spindle rotation axis has been tuned based on measurements.
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[fn:test_id31_3]The "PEPU" [[cite:&hino18_posit_encod_proces_unit]] was used for digital protocol conversion between the interferometers and the Speedgoat.
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[fn:test_id31_2]M12/F40 model from Attocube.
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[fn:test_id31_1]Depending on the measuring range, gap can range from $\approx 1\,\mu m$ to $\approx 100\,\mu m$.
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