diff --git a/content/zettels/complementary_filters.md b/content/zettels/complementary_filters.md
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--- a/content/zettels/complementary_filters.md
+++ b/content/zettels/complementary_filters.md
@@ -4,13 +4,15 @@ author = ["Thomas Dehaeze"]
draft = false
+++
-Backlinks:
-
-- [Advances in internal model control technique: a review and future prospects]({{< relref "saxena12_advan_inter_model_contr_techn" >}})
-- [Actuator Fusion]({{< relref "actuator_fusion" >}})
-- [Sensor Fusion]({{< relref "sensor_fusion" >}})
-
Tags
:
-<./biblio/references.bib>
+
+## Complementary Filters Synthesis {#complementary-filters-synthesis}
+
+The shaping of complementary filters can be done using the \\(\mathcal{H}\_\infty\\) synthesis ([Dehaeze, Vermat, and Christophe 2019](#orgc79060a)).
+
+
+## Bibliography {#bibliography}
+
+Dehaeze, Thomas, Mohit Vermat, and Collette Christophe. 2019. “Complementary Filters Shaping Using \\(mathcalH\_Infty\\) Synthesis.” In _7th International Conference on Control, Mechatronics and Automation (ICCMA)_, 459–64. .
diff --git a/content/zettels/electronic_active_filters.md b/content/zettels/electronic_active_filters.md
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++++
+title = "Electronic Active Filters"
+author = ["Thomas Dehaeze"]
+draft = false
++++
+
+Tags
+: [Operational Amplifiers]({{< relref "operational_amplifiers" >}})
+
+TODOS:
+
+- [X] Electronics circuits containing input voltage, output voltage, Op-amp, RLC components
+- [ ] Bode plots of the filters
+- [ ] Inputs and output impedance
+
+
+## Low Pass Filter {#low-pass-filter}
+
+\begin{equation}
+ \frac{V\_o}{V\_i}(s) = \frac{1}{R^2 C\_1 C\_2 s^2 + 2 R C\_2 s + 1}
+\end{equation}
+
+\begin{equation}
+ \frac{V\_o}{V\_i}(s) = \frac{1}{\frac{s^2}{\omega\_0^2} + 2 \xi \frac{s}{\omega\_0} + 1}
+\end{equation}
+
+With:
+
+- \\(\omega\_0 = \frac{1}{R\sqrt{C\_1 C\_2}}\\)
+- \\(\xi = \frac{C\_2}{C\_1}\\)
+
+
+
+{{< figure src="/ox-hugo/elec_active_second_order_low_pass_filter.png" caption="Figure 1: Second Order Low Pass Filter" >}}
+
+
+## High Pass Filter {#high-pass-filter}
+
+Same as [1](#org21a1d35) but by exchanging R1 with C1 and R2 with C2
+
+\begin{equation}
+ \frac{V\_o}{V\_i}(s) = \frac{R^2 C\_1 C\_2 s^2}{R^2 C\_1 C\_2 s^2 + 2 R C\_2 s + 1}
+\end{equation}
+
+With:
+
+- \\(\omega\_0 = \frac{1}{R\sqrt{C\_1 C\_2}}\\)
+- \\(\xi = \frac{C\_2}{C\_1}\\)
+
+<./biblio/references.bib>
diff --git a/content/zettels/electronic_passive_filters.md b/content/zettels/electronic_passive_filters.md
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@@ -0,0 +1,44 @@
++++
+title = "Electronic Passive Filters"
+author = ["Thomas Dehaeze"]
+draft = false
++++
+
+Tags
+:
+
+TODOS:
+
+- [X] Electronics circuits containing input voltage, output voltage, R L and C components
+- [ ] Bode plot of the filter from input voltage to output voltage
+- [ ] Equation of the transfer functions with nice parameters (\\(\omega\_c\\), \\(\xi\\))
+
+
+## First Order Low Pass Filter {#first-order-low-pass-filter}
+
+
+
+{{< figure src="/ox-hugo/elec_passive_first_order_low_pass_filter.png" caption="Figure 1: First Order Low Pass Filter using an RC circuit" >}}
+
+
+## First Order High Pass Filter {#first-order-high-pass-filter}
+
+
+
+{{< figure src="/ox-hugo/elec_passive_first_order_high_pass_filter.png" caption="Figure 2: First Order High Pass Filter using an RC circuit" >}}
+
+
+## Second Order Low Pass Filter {#second-order-low-pass-filter}
+
+
+
+{{< figure src="/ox-hugo/elec_passive_second_order_low_pass_filter.png" caption="Figure 3: Second Order Low Pass Filter using an RLC circuit" >}}
+
+
+## Second Order High Pass Filter {#second-order-high-pass-filter}
+
+
+
+{{< figure src="/ox-hugo/elec_passive_second_order_high_pass_filter.png" caption="Figure 4: Second Order High Pass Filter using an RLC circuit" >}}
+
+<./biblio/references.bib>
diff --git a/content/zettels/mass_spring_damper_systems.md b/content/zettels/mass_spring_damper_systems.md
index 4fd835e..d189389 100644
--- a/content/zettels/mass_spring_damper_systems.md
+++ b/content/zettels/mass_spring_damper_systems.md
@@ -7,4 +7,52 @@ draft = false
Tags
:
+
+## Actuated Mass Spring Damper System {#actuated-mass-spring-damper-system}
+
+Let's consider Figure [1](#orgeec8f0f) where:
+
+- \\(m\\) is the mass in [kg]
+- \\(ḱ\\) is the spring stiffness in [N/m]
+- \\(c\\) is the damping coefficient in [N/(m/s)]
+- \\(F\\) is the actuator force in [N]
+- \\(F\_d\\) is external force applied to the mass in [N]
+- \\(w\\) is ground motion
+- \\(x\\) is the absolute mass motion
+
+
+
+{{< figure src="/ox-hugo/mass_spring_damper_system.png" caption="Figure 1: Mass Spring Damper System" >}}
+
+Let's write the transfer function from \\(F\\) to \\(x\\):
+
+\begin{equation}
+ \frac{x}{F}(s) = \frac{1}{m s^2 + c s + k}
+\end{equation}
+
+This can be re-written as:
+
+\begin{equation}
+ \frac{x}{F}(s) = \frac{1/k}{\frac{s^2}{\omega\_0^2} + 2 \xi \frac{s}{\omega\_0} + 1}
+\end{equation}
+
+with:
+
+- \\(\omega\_0\\) the natural frequency in [rad/s]
+- \\(\xi\\) the damping ratio
+
+
+## Transmissibility {#transmissibility}
+
+\begin{equation}
+ \frac{x}{w}(s) = \frac{1}{\frac{s^2}{\omega\_0^2} + 2 \xi \frac{s}{\omega\_0} + 1}
+\end{equation}
+
+
+## Compliance {#compliance}
+
+\begin{equation}
+ \frac{x}{F\_d}(s) = \frac{1/k}{\frac{s^2}{\omega\_0^2} + 2 \xi \frac{s}{\omega\_0} + 1}
+\end{equation}
+
<./biblio/references.bib>
diff --git a/content/zettels/operational_amplifiers.md b/content/zettels/operational_amplifiers.md
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++++
+title = "Operational Amplifiers"
+author = ["Thomas Dehaeze"]
+draft = false
++++
+
+Tags
+:
+
+<./biblio/references.bib>
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