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Add picture of the vionic encoder

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Thomas Dehaeze
2021-01-04 11:44:11 +01:00
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3 changed files with 38 additions and 27 deletions
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"> <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
<head> <head>
<!-- 2020-12-17 jeu. 14:54 --> <!-- 2021-01-04 lun. 11:44 -->
<meta http-equiv="Content-Type" content="text/html;charset=utf-8" /> <meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
<title>Encoder Renishaw Vionic - Test Bench</title> <title>Encoder Renishaw Vionic - Test Bench</title>
<meta name="generator" content="Org mode" /> <meta name="generator" content="Org mode" />
@@ -30,15 +30,15 @@
<h2>Table of Contents</h2> <h2>Table of Contents</h2>
<div id="text-table-of-contents"> <div id="text-table-of-contents">
<ul> <ul>
<li><a href="#org52a1b18">1. Encoder Model</a></li> <li><a href="#org55157ef">1. Encoder Model</a></li>
<li><a href="#org79c9cb0">2. Test-Bench Description</a></li> <li><a href="#org8ef40ec">2. Test-Bench Description</a></li>
<li><a href="#org68a3dfb">3. Measurement procedure</a></li> <li><a href="#orgce223ed">3. Measurement procedure</a></li>
<li><a href="#orgf207a65">4. Measurement Results</a></li> <li><a href="#org51852cb">4. Measurement Results</a></li>
</ul> </ul>
</div> </div>
</div> </div>
<div class="note" id="orgf5882b4"> <div class="note" id="org4436bab">
<p> <p>
You can find below the document of: You can find below the document of:
</p> </p>
@@ -62,8 +62,15 @@ In particular, we would like to measure:
<li>Linearity of the sensor</li> <li>Linearity of the sensor</li>
</ul> </ul>
<div id="outline-container-org52a1b18" class="outline-2">
<h2 id="org52a1b18"><span class="section-number-2">1</span> Encoder Model</h2> <div id="orgeb4726b" class="figure">
<p><img src="figs/encoder_vionic.png" alt="encoder_vionic.png" />
</p>
<p><span class="figure-number">Figure 1: </span>Picture of the Vionic Encoder</p>
</div>
<div id="outline-container-org55157ef" class="outline-2">
<h2 id="org55157ef"><span class="section-number-2">1</span> Encoder Model</h2>
<div class="outline-text-2" id="text-1"> <div class="outline-text-2" id="text-1">
<p> <p>
The Encoder is characterized by its dynamics \(G_m(s)\) from the &ldquo;true&rdquo; displacement \(y\) to measured displacement \(y_m\). The Encoder is characterized by its dynamics \(G_m(s)\) from the &ldquo;true&rdquo; displacement \(y\) to measured displacement \(y_m\).
@@ -75,18 +82,18 @@ It is also characterized by its measurement noise \(n\) that can be described by
</p> </p>
<p> <p>
The model of the encoder is shown in Figure <a href="#org131b7a7">1</a>. The model of the encoder is shown in Figure <a href="#org2d59f14">2</a>.
</p> </p>
<div id="org131b7a7" class="figure"> <div id="org2d59f14" class="figure">
<p><img src="figs/encoder-model-schematic.png" alt="encoder-model-schematic.png" /> <p><img src="figs/encoder-model-schematic.png" alt="encoder-model-schematic.png" />
</p> </p>
<p><span class="figure-number">Figure 1: </span>Model of the Encoder</p> <p><span class="figure-number">Figure 2: </span>Model of the Encoder</p>
</div> </div>
<table id="org00cec14" border="2" cellspacing="0" cellpadding="6" rules="groups" frame="hsides"> <table id="org476b3d6" border="2" cellspacing="0" cellpadding="6" rules="groups" frame="hsides">
<caption class="t-above"><span class="table-number">Table 1:</span> Characteristics of the Vionic Encoder</caption> <caption class="t-above"><span class="table-number">Table 1:</span> Characteristics of the Vionic Encoder</caption>
<colgroup> <colgroup>
@@ -120,17 +127,17 @@ The model of the encoder is shown in Figure <a href="#org131b7a7">1</a>.
<div id="orgd22d423" class="figure"> <div id="orgb8bf3d5" class="figure">
<p><img src="./figs/vionic_expected_noise.png" alt="vionic_expected_noise.png" /> <p><img src="./figs/vionic_expected_noise.png" alt="vionic_expected_noise.png" />
</p> </p>
<p><span class="figure-number">Figure 2: </span>Expected interpolation errors for the Vionic Encoder</p> <p><span class="figure-number">Figure 3: </span>Expected interpolation errors for the Vionic Encoder</p>
</div> </div>
</div> </div>
</div> </div>
<div id="outline-container-org79c9cb0" class="outline-2"> <div id="outline-container-org8ef40ec" class="outline-2">
<h2 id="org79c9cb0"><span class="section-number-2">2</span> Test-Bench Description</h2> <h2 id="org8ef40ec"><span class="section-number-2">2</span> Test-Bench Description</h2>
<div class="outline-text-2" id="text-2"> <div class="outline-text-2" id="text-2">
<p> <p>
To measure the noise \(n\) of the encoder, one can rigidly fix the head and the ruler together such that no motion should be measured. To measure the noise \(n\) of the encoder, one can rigidly fix the head and the ruler together such that no motion should be measured.
@@ -144,7 +151,7 @@ An actuator should also be there so impose a displacement.
</p> </p>
<p> <p>
One idea is to use the test-bench shown in Figure <a href="#org1bd058e">3</a>. One idea is to use the test-bench shown in Figure <a href="#org1fd5a94">4</a>.
</p> </p>
<p> <p>
@@ -157,37 +164,37 @@ As the interferometer has a very large bandwidth, we should be able to estimate
</p> </p>
<div id="org1bd058e" class="figure"> <div id="org1fd5a94" class="figure">
<p><img src="figs/test_bench_encoder_calibration.png" alt="test_bench_encoder_calibration.png" /> <p><img src="figs/test_bench_encoder_calibration.png" alt="test_bench_encoder_calibration.png" />
</p> </p>
<p><span class="figure-number">Figure 3: </span>Schematic of the test bench</p> <p><span class="figure-number">Figure 4: </span>Schematic of the test bench</p>
</div> </div>
<p> <p>
To measure the noise of the sensor, we can also simply measure the output signal when the relative motion between the encoder and the ruler is null. To measure the noise of the sensor, we can also simply measure the output signal when the relative motion between the encoder and the ruler is null.
This can be done by clamping the two as done in the mounting strut tool (Figure <a href="#orgfdf8d08">4</a>). This can be done by clamping the two as done in the mounting strut tool (Figure <a href="#orgab0ed8d">5</a>).
</p> </p>
<div id="orgfdf8d08" class="figure"> <div id="orgab0ed8d" class="figure">
<p><img src="figs/test_bench_measure_noise.png" alt="test_bench_measure_noise.png" /> <p><img src="figs/test_bench_measure_noise.png" alt="test_bench_measure_noise.png" />
</p> </p>
<p><span class="figure-number">Figure 4: </span>Mounting Strut test bench as a clamping method to measure the encoder noise.</p> <p><span class="figure-number">Figure 5: </span>Mounting Strut test bench as a clamping method to measure the encoder noise.</p>
</div> </div>
</div> </div>
</div> </div>
<div id="outline-container-org68a3dfb" class="outline-2"> <div id="outline-container-orgce223ed" class="outline-2">
<h2 id="org68a3dfb"><span class="section-number-2">3</span> Measurement procedure</h2> <h2 id="orgce223ed"><span class="section-number-2">3</span> Measurement procedure</h2>
</div> </div>
<div id="outline-container-orgf207a65" class="outline-2"> <div id="outline-container-org51852cb" class="outline-2">
<h2 id="orgf207a65"><span class="section-number-2">4</span> Measurement Results</h2> <h2 id="org51852cb"><span class="section-number-2">4</span> Measurement Results</h2>
</div> </div>
</div> </div>
<div id="postamble" class="status"> <div id="postamble" class="status">
<p class="author">Author: Dehaeze Thomas</p> <p class="author">Author: Dehaeze Thomas</p>
<p class="date">Created: 2020-12-17 jeu. 14:54</p> <p class="date">Created: 2021-01-04 lun. 11:44</p>
</div> </div>
</body> </body>
</html> </html>

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@@ -55,6 +55,10 @@ In particular, we would like to measure:
- Bandwidth of the sensor - Bandwidth of the sensor
- Linearity of the sensor - Linearity of the sensor
#+name: fig:encoder_vionic
#+caption: Picture of the Vionic Encoder
[[file:figs/encoder_vionic.png]]
* Encoder Model * Encoder Model
The Encoder is characterized by its dynamics $G_m(s)$ from the "true" displacement $y$ to measured displacement $y_m$. The Encoder is characterized by its dynamics $G_m(s)$ from the "true" displacement $y$ to measured displacement $y_m$.
Ideally, this dynamics is constant over a wide frequency band with very small phase drop. Ideally, this dynamics is constant over a wide frequency band with very small phase drop.