Update files for new definition of hexapods
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
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<head>
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<!-- 2020-04-17 ven. 09:35 -->
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<!-- 2020-05-05 mar. 10:33 -->
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<meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
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<title>Effect of Uncertainty on the payload’s dynamics on the isolation platform dynamics</title>
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<meta name="generator" content="Org mode" />
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@@ -37,17 +37,17 @@
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<ul>
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<li><a href="#orgcc5f0ec">1. Simple Introductory Example</a>
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<ul>
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<li><a href="#orgf75e223">1.1. Equations of motion</a></li>
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<li><a href="#org5ed1517">1.1. Equations of motion</a></li>
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<li><a href="#org4efccbf">1.2. Initialization of the payload dynamics</a></li>
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<li><a href="#orgb400ca3">1.3. Initialization of the isolation platform</a></li>
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<li><a href="#orgd0dd88b">1.4. Comparison</a></li>
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<li><a href="#orgd1e600e">1.5. Conclusion</a></li>
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<li><a href="#org3f697cc">1.5. Conclusion</a></li>
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</ul>
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</li>
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<li><a href="#org1f8e63e">2. Generalization to arbitrary dynamics</a>
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<ul>
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<li><a href="#orgc4fa63e">2.1. Introduction</a></li>
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<li><a href="#org5ed1517">2.2. Equations of motion</a></li>
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<li><a href="#org3367211">2.2. Equations of motion</a></li>
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<li><a href="#orge217a33">2.3. Impedance \(G^\prime(s)\) of a mass-spring-damper payload</a></li>
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<li><a href="#org0ee44da">2.4. First Analytical analysis</a></li>
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<li><a href="#orgfe81c1c">2.5. Impedance of the Payload and Dynamical Uncertainty</a></li>
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@@ -60,7 +60,7 @@
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<li><a href="#org9086831">2.8.3. Effect of the platform’s mass \(m\)</a></li>
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</ul>
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</li>
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<li><a href="#org3f697cc">2.9. Conclusion</a></li>
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<li><a href="#org272e76a">2.9. Conclusion</a></li>
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</ul>
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</li>
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</ul>
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@@ -114,8 +114,8 @@ The goal is to stabilize \(x\) using \(F\) in spite of uncertainty on the payloa
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</div>
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</div>
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<div id="outline-container-orgf75e223" class="outline-3">
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<h3 id="orgf75e223"><span class="section-number-3">1.1</span> Equations of motion</h3>
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<div id="outline-container-org5ed1517" class="outline-3">
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<h3 id="org5ed1517"><span class="section-number-3">1.1</span> Equations of motion</h3>
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<div class="outline-text-3" id="text-1-1">
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<p>
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If we write the equation of motion of the system in Figure <a href="#orgaa77a57">1</a>, we obtain:
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@@ -152,8 +152,8 @@ Let the payload have:
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kpi = 5e6;
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cpi = 3e3;
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kpi = (2<span class="org-type">*</span><span class="org-constant">pi</span><span class="org-type">*</span>50)<span class="org-type">^</span>2<span class="org-type">*</span>mpi;
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cpi = 0.2<span class="org-type">*</span>sqrt(kpi<span class="org-type">*</span>mpi);
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kpi = (2*pi*50)^2*mpi;
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cpi = 0.2*sqrt(kpi*mpi);
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</pre>
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</div>
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@@ -161,9 +161,9 @@ cpi = 0.2<span class="org-type">*</span>sqrt(kpi<span class="org-type">*</span>m
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Let’s also consider some uncertainty in those parameters:
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</p>
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<div class="org-src-container">
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<pre class="src src-matlab">mp = ureal(<span class="org-string">'m'</span>, mpi, <span class="org-string">'Range'</span>, [1, 100]);
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cp = ureal(<span class="org-string">'c'</span>, cpi, <span class="org-string">'Percentage'</span>, 30);
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kp = ureal(<span class="org-string">'k'</span>, kpi, <span class="org-string">'Percentage'</span>, 30);
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<pre class="src src-matlab">mp = ureal('m', mpi, 'Range', [1, 100]);
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cp = ureal('c', cpi, 'Percentage', 30);
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kp = ureal('k', kpi, 'Percentage', 30);
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</pre>
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</div>
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@@ -222,8 +222,8 @@ The obtained dynamics from \(F\) to \(x\) for the three isolation platform are s
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</div>
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</div>
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<div id="outline-container-orgd1e600e" class="outline-3">
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<h3 id="orgd1e600e"><span class="section-number-3">1.5</span> Conclusion</h3>
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<div id="outline-container-org3f697cc" class="outline-3">
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<h3 id="org3f697cc"><span class="section-number-3">1.5</span> Conclusion</h3>
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<div class="outline-text-3" id="text-1-5">
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<div class="important">
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<p>
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@@ -275,8 +275,8 @@ Now let’s consider the system consisting of a mass-spring-system (the isol
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</div>
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</div>
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<div id="outline-container-org5ed1517" class="outline-3">
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<h3 id="org5ed1517"><span class="section-number-3">2.2</span> Equations of motion</h3>
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<div id="outline-container-org3367211" class="outline-3">
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<h3 id="org3367211"><span class="section-number-3">2.2</span> Equations of motion</h3>
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<div class="outline-text-3" id="text-2-2">
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<p>
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We have to following equations of motion:
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@@ -343,7 +343,7 @@ And we obtain
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\end{align*}
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<p>
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Which is the same transfer function that was obtained in section <a href="#org971d11c">1</a> (Eq. \eqref{orge5d69a3}).
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Which is the same transfer function that was obtained in section <a href="#org971d11c">1</a> (Eq. \eqref{eq:plant_simple_system}).
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</p>
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<p>
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@@ -455,7 +455,7 @@ The main resonance of the payload is then \(\omega^\prime = \sqrt{\frac{m^\prime
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c0 = 3e2;
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k0 = 5e5;
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Gp0 = (m0<span class="org-type">*</span>s<span class="org-type">^</span>2 <span class="org-type">*</span> (c0<span class="org-type">*</span>s <span class="org-type">+</span> k0))<span class="org-type">/</span>(m0<span class="org-type">*</span>s<span class="org-type">^</span>2 <span class="org-type">+</span> c0<span class="org-type">*</span>s <span class="org-type">+</span> k0);
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Gp0 = (m0*s^2 * (c0*s + k0))/(m0*s^2 + c0*s + k0);
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</pre>
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</div>
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@@ -486,10 +486,10 @@ The parameters are defined below.
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</p>
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<div class="org-src-container">
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<pre class="src src-matlab">r0 = 0.5;
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tau = 1<span class="org-type">/</span>(50<span class="org-type">*</span>2<span class="org-type">*</span><span class="org-constant">pi</span>);
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tau = 1/(50*2*pi);
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rinf = 10;
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wI = (tau<span class="org-type">*</span>s <span class="org-type">+</span> r0)<span class="org-type">/</span>((tau<span class="org-type">/</span>rinf)<span class="org-type">*</span>s <span class="org-type">+</span> 1);
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wI = (tau*s + r0)/((tau/rinf)*s + 1);
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</pre>
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</div>
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@@ -497,7 +497,7 @@ wI = (tau<span class="org-type">*</span>s <span class="org-type">+</span> r0)<sp
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We then generate a complex \(\Delta\).
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</p>
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<div class="org-src-container">
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<pre class="src src-matlab">DeltaI = ucomplex(<span class="org-string">'A'</span>,0);
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<pre class="src src-matlab">DeltaI = ucomplex('A',0);
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</pre>
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</div>
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@@ -505,7 +505,7 @@ We then generate a complex \(\Delta\).
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We generate the uncertain plant \(G^\prime(s)\).
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</p>
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<div class="org-src-container">
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<pre class="src src-matlab">Gp = Gp0<span class="org-type">*</span>(1<span class="org-type">+</span>wI<span class="org-type">*</span>DeltaI);
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<pre class="src src-matlab">Gp = Gp0*(1+wI*DeltaI);
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</pre>
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</div>
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@@ -583,12 +583,12 @@ And we generate three isolation platforms:
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Soft Isolation Platform:
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</p>
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<div class="org-src-container">
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<pre class="src src-matlab">k_soft = m<span class="org-type">*</span>(2<span class="org-type">*</span><span class="org-constant">pi</span><span class="org-type">*</span>5)<span class="org-type">^</span>2;
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c_soft = 0.1<span class="org-type">*</span>sqrt(m<span class="org-type">*</span>k_soft);
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<pre class="src src-matlab">k_soft = m*(2*pi*5)^2;
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c_soft = 0.1*sqrt(m*k_soft);
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G_soft = 1<span class="org-type">/</span>(m<span class="org-type">*</span>s<span class="org-type">^</span>2 <span class="org-type">+</span> c_soft<span class="org-type">*</span>s <span class="org-type">+</span> k_soft <span class="org-type">+</span> Gp);
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G0_soft = 1<span class="org-type">/</span>(m<span class="org-type">*</span>s<span class="org-type">^</span>2 <span class="org-type">+</span> c_soft<span class="org-type">*</span>s <span class="org-type">+</span> k_soft <span class="org-type">+</span> Gp0);
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wiI_soft = Gp0<span class="org-type">*</span>G0_soft<span class="org-type">*</span>wI;
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G_soft = 1/(m*s^2 + c_soft*s + k_soft + Gp);
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G0_soft = 1/(m*s^2 + c_soft*s + k_soft + Gp0);
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wiI_soft = Gp0*G0_soft*wI;
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</pre>
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</div>
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@@ -596,12 +596,12 @@ wiI_soft = Gp0<span class="org-type">*</span>G0_soft<span class="org-type">*</sp
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Mid Isolation Platform
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</p>
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<div class="org-src-container">
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<pre class="src src-matlab">k_mid = m<span class="org-type">*</span>(2<span class="org-type">*</span><span class="org-constant">pi</span><span class="org-type">*</span>50)<span class="org-type">^</span>2;
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c_mid = 0.1<span class="org-type">*</span>sqrt(m<span class="org-type">*</span>k_mid);
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<pre class="src src-matlab">k_mid = m*(2*pi*50)^2;
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c_mid = 0.1*sqrt(m*k_mid);
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G_mid = 1<span class="org-type">/</span>(m<span class="org-type">*</span>s<span class="org-type">^</span>2 <span class="org-type">+</span> c_mid<span class="org-type">*</span>s <span class="org-type">+</span> k_mid <span class="org-type">+</span> Gp);
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G0_mid = 1<span class="org-type">/</span>(m<span class="org-type">*</span>s<span class="org-type">^</span>2 <span class="org-type">+</span> c_mid<span class="org-type">*</span>s <span class="org-type">+</span> k_mid <span class="org-type">+</span> Gp0);
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wiI_mid = Gp0<span class="org-type">*</span>G0_mid<span class="org-type">*</span>wI;
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G_mid = 1/(m*s^2 + c_mid*s + k_mid + Gp);
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G0_mid = 1/(m*s^2 + c_mid*s + k_mid + Gp0);
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wiI_mid = Gp0*G0_mid*wI;
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</pre>
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</div>
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@@ -609,12 +609,12 @@ wiI_mid = Gp0<span class="org-type">*</span>G0_mid<span class="org-type">*</span
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Stiff Isolation Platform
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</p>
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<div class="org-src-container">
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<pre class="src src-matlab">k_stiff = m<span class="org-type">*</span>(2<span class="org-type">*</span><span class="org-constant">pi</span><span class="org-type">*</span>500)<span class="org-type">^</span>2;
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c_stiff = 0.1<span class="org-type">*</span>sqrt(m<span class="org-type">*</span>k_stiff);
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<pre class="src src-matlab">k_stiff = m*(2*pi*500)^2;
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c_stiff = 0.1*sqrt(m*k_stiff);
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G_stiff = 1<span class="org-type">/</span>(m<span class="org-type">*</span>s<span class="org-type">^</span>2 <span class="org-type">+</span> c_stiff<span class="org-type">*</span>s <span class="org-type">+</span> k_stiff <span class="org-type">+</span> Gp);
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G0_stiff = 1<span class="org-type">/</span>(m<span class="org-type">*</span>s<span class="org-type">^</span>2 <span class="org-type">+</span> c_stiff<span class="org-type">*</span>s <span class="org-type">+</span> k_stiff <span class="org-type">+</span> Gp0);
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wiI_stiff = Gp0<span class="org-type">*</span>G0_stiff<span class="org-type">*</span>wI;
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G_stiff = 1/(m*s^2 + c_stiff*s + k_stiff + Gp);
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G0_stiff = 1/(m*s^2 + c_stiff*s + k_stiff + Gp0);
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wiI_stiff = Gp0*G0_stiff*wI;
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</pre>
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</div>
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@@ -732,8 +732,8 @@ Let’s fix \(k = 10^7\ [N/m]\), \(\xi = \frac{c}{2\sqrt{km}} = 0.1\) and se
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</div>
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</div>
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<div id="outline-container-org3f697cc" class="outline-3">
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<h3 id="org3f697cc"><span class="section-number-3">2.9</span> Conclusion</h3>
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<div id="outline-container-org272e76a" class="outline-3">
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<h3 id="org272e76a"><span class="section-number-3">2.9</span> Conclusion</h3>
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<div class="outline-text-3" id="text-2-9">
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<div class="important">
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<p>
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@@ -757,7 +757,7 @@ In that case, maximizing the stiffness of the payload is a good idea.
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</div>
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<div id="postamble" class="status">
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<p class="author">Author: Dehaeze Thomas</p>
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<p class="date">Created: 2020-04-17 ven. 09:35</p>
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<p class="date">Created: 2020-05-05 mar. 10:33</p>
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</div>
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</body>
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</html>
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