Update Content - 2020-11-23

content/zettels/direct_velocity_feedback.md

@@ -0,0 +1,10 @@
++++
+title = "Direct Velocity Feedback"
+author = ["Thomas Dehaeze"]
+draft = false
++++
+
+Tags
+: [Active Damping]({{< relref "active_damping" >}})
+
+<./biblio/references.bib>

content/zettels/integral_force_feedback.md

@@ -0,0 +1,10 @@
++++
+title = "Integral Force Feedback"
+author = ["Thomas Dehaeze"]
+draft = false
++++
+
+Tags
+: [Active Damping]({{< relref "active_damping" >}})
+
+<./biblio/references.bib>

content/zettels/interferometers.md

@@ -4,10 +4,6 @@ author = ["Thomas Dehaeze"]
 draft = false
 +++
 
-Backlinks:
-
--   [Position Sensors]({{< relref "position_sensors" >}})
-
 Tags
 : [Position Sensors]({{< relref "position_sensors" >}})
 
@@ -26,10 +22,31 @@ Tags
 | Optics11      | [link](https://optics11.com/)                                                                            | Netherlands |
 
 
-## Environmental Units {#environmental-units}
+## Effect of Refractive Index - Environmental Units {#effect-of-refractive-index-environmental-units}
 
+The measured distance is proportional to the refractive index of the air that depends on several quantities as shown in Table [1](#table--tab:index-air) (Taken from ([Thurner et al. 2015](#org7c4b7ca))).
+
+<a id="table--tab:index-air"></a>
 <div class="table-caption">
-  <span class="table-number">Table 1</span>:
+  <span class="table-number"><a href="#table--tab:index-air">Table 1</a></span>:
+  Dependence of Refractive Index \(n\) of Air from Temperature \(T\), pressure \(p\), Humidity \(h\), and CO2 content \(x_c\). Taken around \(T = 20^oC\), \(p=101kPa\), \(h = 50\%\), \(x_c = 400 ppm\) and \(\lambda = 1530nm\)
+</div>
+
+| Physical Value                        | Refractive Index Sensitivity | Value                     |
+|---------------------------------------|------------------------------|---------------------------|
+| Temperature \\(T\\)                   | \\(dn/dT\ (K^{-1})\\)        | \\(-9.32\cdot 10^{-7}\\)  |
+| Pressure \\(p\\)                      | \\(dn/dp\ (mbar^{-1})\\)     | \\(2.70\cdot 10^{-7}\\)   |
+| Humidity \\(h\\)                      | \\(dn/dh\ (\text{%}^{-1})\\) | \\(-8.72\cdot 10^{-9}\\)  |
+| \\(\text{CO}\_2\\) content \\(x\_c\\) | \\(dn/dx\_c\ (ppm^{-1})\\)   | \\(1.42\cdot 10^{-10}\\)  |
+| Wavelength \\(\lambda\\)              | \\(dn/d\lambda\ (nm^{-1})\\) | \\(-8.59\cdot 10^{-10}\\) |
+
+In order to limit the measurement uncertainty due to variation of air parameters, an Environmental Unit can be used that typically measures the temperature, pressure and humidity and compensation for the variation of refractive index in real time.
+
+Typical characteristics of commercial environmental units are shown in Table [2](#table--tab:environmental-units).
+
+<a id="table--tab:environmental-units"></a>
+<div class="table-caption">
+  <span class="table-number"><a href="#table--tab:environmental-units">Table 2</a></span>:
   Characteristics of Environmental Units
 </div>
 
@@ -42,16 +59,16 @@ Tags
 
 ## Interferometer Precision {#interferometer-precision}
 
-([Jang and Kim 2017](#orgc0eaaa4))
+Figure [1](#orgb0b437f) shows the expected precision as a function of the measured distance due to change of refractive index of the air (taken from ([Jang and Kim 2017](#org60051d3))).
 
-<a id="orge2a3743"></a>
+<a id="orgb0b437f"></a>
 
 {{< figure src="/ox-hugo/position_sensor_interferometer_precision.png" caption="Figure 1: Expected precision of interferometer as a function of measured distance" >}}
 
 
 ## Sources of uncertainty {#sources-of-uncertainty}
 
-Sources of error in laser interferometry are well described in ([Ducourtieux 2018](#org2c23555)).
+Sources of error in laser interferometry are well described in ([Ducourtieux 2018](#orgd3162b8)).
 
 It includes:
 
@@ -61,16 +78,18 @@ It includes:
     -   Pressure: \\(K\_P \approx 0.27 ppm hPa^{-1}\\)
     -   Humidity: \\(K\_{HR} \approx 0.01 ppm \% RH^{-1}\\)
     -   These errors can partially be compensated using an environmental unit.
--   Air turbulence (Figure [2](#org92b4926))
+-   Air turbulence (Figure [2](#org74b0d34))
 -   Non linearity
 
-<a id="org92b4926"></a>
+<a id="org74b0d34"></a>
 
 {{< figure src="/ox-hugo/interferometers_air_turbulence.png" caption="Figure 2: Effect of air turbulences on measurement stability" >}}
 
 
 ## Bibliography {#bibliography}
 
-<a id="org2c23555"></a>Ducourtieux, Sebastien. 2018. “Toward High Precision Position Control Using Laser Interferometry: Main Sources of Error.” <https://doi.org/10.13140/rg.2.2.21044.35205>.
+<a id="orgd3162b8"></a>Ducourtieux, Sebastien. 2018. “Toward High Precision Position Control Using Laser Interferometry: Main Sources of Error.” <https://doi.org/10.13140/rg.2.2.21044.35205>.
 
-<a id="orgc0eaaa4"></a>Jang, Yoon-Soo, and Seung-Woo Kim. 2017. “Compensation of the Refractive Index of Air in Laser Interferometer for Distance Measurement: A Review.” _International Journal of Precision Engineering and Manufacturing_ 18 (12):1881–90. <https://doi.org/10.1007/s12541-017-0217-y>.
+<a id="org60051d3"></a>Jang, Yoon-Soo, and Seung-Woo Kim. 2017. “Compensation of the Refractive Index of Air in Laser Interferometer for Distance Measurement: A Review.” _International Journal of Precision Engineering and Manufacturing_ 18 (12):1881–90. <https://doi.org/10.1007/s12541-017-0217-y>.
+
+<a id="org7c4b7ca"></a>Thurner, Klaus, Francesca Paola Quacquarelli, Pierre-François Braun, Claudio Dal Savio, and Khaled Karrai. 2015. “Fiber-Based Distance Sensing Interferometry.” _Applied Optics_ 54 (10). Optical Society of America:3051–63.

content/zettels/position_sensors.md

@@ -4,19 +4,6 @@ author = ["Thomas Dehaeze"]
 draft = false
 +++
 
-Backlinks:
-
--   [A review of nanometer resolution position sensors: operation and performance]({{< relref "fleming13_review_nanom_resol_posit_sensor" >}})
--   [Measurement technologies for precision positioning]({{< relref "gao15_measur_techn_precis_posit" >}})
--   [Inertial Sensors]({{< relref "inertial_sensors" >}})
--   [Sensors]({{< relref "sensors" >}})
--   [Collocated Control]({{< relref "collocated_control" >}})
--   [Encoders]({{< relref "encoders" >}})
--   [Eddy Current Sensors]({{< relref "eddy_current_sensors" >}})
--   [Linear variable differential transformers]({{< relref "linear_variable_differential_transformers" >}})
--   [Interferometers]({{< relref "interferometers" >}})
--   [Capacitive Sensors]({{< relref "capacitive_sensors" >}})
-
 Tags
 : [Inertial Sensors]({{< relref "inertial_sensors" >}}), [Force Sensors]({{< relref "force_sensors" >}}), [Sensor Fusion]({{< relref "sensor_fusion" >}}), [Signal Conditioner]({{< relref "signal_conditioner" >}}), [Signal to Noise Ratio]({{< relref "signal_to_noise_ratio" >}})
 
@@ -34,7 +21,7 @@ High precision positioning sensors include:
 
 ## Reviews of Relative Position Sensors {#reviews-of-relative-position-sensors}
 
--   Fleming, A. J., A review of nanometer resolution position sensors: operation and performance ([Fleming 2013](#org151c0ec)) ([Notes]({{< relref "fleming13_review_nanom_resol_posit_sensor" >}}))
+-   Fleming, A. J., A review of nanometer resolution position sensors: operation and performance ([Fleming 2013](#org0cb5981)) ([Notes]({{< relref "fleming13_review_nanom_resol_posit_sensor" >}}))
 
 <a id="table--tab:characteristics-relative-sensor"></a>
 <div class="table-caption">
@@ -70,7 +57,11 @@ High precision positioning sensors include:
 
 Capacitive Sensors and Eddy-Current sensors are compare [here](https://www.lionprecision.com/comparing-capacitive-and-eddy-current-sensors/).
 
+<a id="org12bd001"></a>
+
+{{< figure src="/ox-hugo/position_sensors_thurner15.png" caption="Figure 1: Overview of range and precision of different position displacement sensors. Taken from <sup id=\"53230532ada812541a7cd984b3aa2662\"><a href=\"#thurner15_fiber_based_distan_sensin_inter\" title=\"Thurner, Quacquarelli, Braun, Pierre-Fran\ccois, Dal Savio, Karrai \&amp; Khaled, Fiber-Based Distance Sensing Interferometry, {Applied optics}, v(10), 3051--3063 (2015).\">thurner15_fiber_based_distan_sensin_inter</a></sup>" >}}
+
 
 ## Bibliography {#bibliography}
 
-<a id="org151c0ec"></a>Fleming, Andrew J. 2013. “A Review of Nanometer Resolution Position Sensors: Operation and Performance.” _Sensors and Actuators a: Physical_ 190 (nil):106–26. <https://doi.org/10.1016/j.sna.2012.10.016>.
+<a id="org0cb5981"></a>Fleming, Andrew J. 2013. “A Review of Nanometer Resolution Position Sensors: Operation and Performance.” _Sensors and Actuators a: Physical_ 190 (nil):106–26. <https://doi.org/10.1016/j.sna.2012.10.016>.

content/zettels/sensors.md

@@ -4,11 +4,6 @@ author = ["Thomas Dehaeze"]
 draft = false
 +++
 
-Backlinks:
-
--   [Signal Conditioner]({{< relref "signal_conditioner" >}})
--   [Sensor Fusion]({{< relref "sensor_fusion" >}})
-
 Tags
 :
 

content/zettels/test/active_damping.md

@@ -0,0 +1,19 @@
++++
+title = "Active Damping"
+author = ["Thomas Dehaeze"]
+draft = false
++++
+
+Tags
+:
+
+There are two main control architecture to actively damp structures:
+
+-   [Integral Force Feedback]({{< relref "integral_force_feedback" >}})
+-   [Direct Velocity Feedback]({{< relref "direct_velocity_feedback" >}})
+
+The idea is to apply a force proportional to the velocity (either relative or inertial) of the structure.
+
+These are usually applied in a collocated way, meaning that the actuator and sensors are collocated (fixed to the same DoF), in order to have guaranteed stability.
+
+<./biblio/references.bib>