added system diagrams to lecture 1

Author: Brad Carman

docs/Project.toml

@@ -13,13 +13,13 @@ Sundials = "c3572dad-4567-51f8-b174-8c6c989267f4"
 Symbolics = "0c5d862f-8b57-4792-8d23-62f2024744c7"
 
 [compat]
-DataInterpolations = "4"
+DataInterpolations = "5"
 DifferentialEquations = "7"
 Documenter = "1"
 ForwardDiff = "0.10"
 ModelingToolkit = "9"
 ModelingToolkitStandardLibrary = "2"
-OrdinaryDiffEq = "6"
+OrdinaryDiffEq = "=6.74.1"
 Plots = "1"
 Setfield = "1"
 Sundials = "4"

docs/make.jl

@@ -1,4 +1,5 @@
 using Documenter, ModelingToolkitCourse
+# NOTE: OrdinaryDiffEq limited to v6.74.1 because of bug https://github.com/SciML/OrdinaryDiffEq.jl/issues/2250
 
 pages = [
     "Home" => "index.md",
@@ -26,5 +27,10 @@ makedocs(sitename = "ModelingToolkit Course",
         canonical = "https://docs.sciml.ai/ModelingToolkitCourse/stable/"),
     pages = pages)
 
+#= 
+using LiveServer
+serve(dir="build")
+=#
+
 deploydocs(repo = "github.com/SciML/ModelingToolkitCourse.git";
     push_preview = true)

docs/src/img/MassSpringDamper.png

@@ -384,12 +384,18 @@ Now the `Mass` and `Damper` components can be assembled in a system and connecte
 end
 
 @mtkbuild sys = System(;v=100, m=5, d=3)
+nothing # hide
+```
+
+![mass-damper](../img/System1.png)
+
+Here we arrive at the following equations
+```@example l1 
 full_equations(sys)
 ```
 
 As can be seen we arrive at the same equation as derived previously.  Now it would be easy to define a system that adds a spring, or has a series of connected masses, springs, dampers, etc.  
 
-
 The `Damper` component created previously was a little incomplete because it only had one port.  In reality a damper or spring will be connected between 2 objects, for example the car frame and the wheel.  Therefore a proper component will define 2 ports so that the component can be as analogous with real life as possible.  In the example below the component is defined properly with 2 ports.  Note the velocity of the component `v` is defined as a relative velocity between the 2 ports.  It's easy to understand how this works if it's assumed that `port_b` is connected to a stationary reference frame.
 
 ```@example l1 
@@ -550,6 +556,13 @@ Now let's assemble a *mass-spring-damper* system with the full collection of com
 end
 
 @mtkbuild sys = System()
+```
+
+![mass-spring-damper](../img/System2.png)
+
+Solving the system gives a plot of the 2 solved uknowns.
+
+```@example l1 
 prob = ODEProblem(sys, [], (0, 10))
 sol = solve(prob)
 plot(sol)
@@ -620,6 +633,8 @@ end
 nothing # hide
 ```
 
+![MassSpringDamper component](../img/MassSpringDamper.png)
+
 As an example, the `MassSpringDamper` component can be connected in series to make a complex system.  One can imagine then how this enables easy construction of complex models that can be quickly modified, extremely useful for the application of model based design.  
 
 ```@example l1
@@ -644,6 +659,14 @@ As an example, the `MassSpringDamper` component can be connected in series to ma
 end
 
 @mtkbuild sys = System()
+nothing #hide
+```
+
+![Composite System](../img/System3.png)
+
+Solving this complex system gives
+
+```@example l1
 prob = ODEProblem(sys, [], (0, 2))
 sol = solve(prob)
 plot(sol; idxs=[sys.msd1.spring.x, sys.msd2.spring.x, sys.msd3.spring.x])

docs/src/img/System1.png

@@ -353,8 +353,6 @@ import ModelingToolkitStandardLibrary.Blocks as B
 using DataInterpolations
 mass_flow_fun = LinearInterpolation(sol_x[ṁ], sol_x.t)
 
-include("volume.jl") # <-- missing Volume component from MTKSL (will be released in new version) 
-
 function MassVolume(; name, dx, drho, dm)
 
     pars = @parameters begin
@@ -373,7 +371,7 @@ function MassVolume(; name, dx, drho, dm)
     systems = @named begin
         fluid = IC.HydraulicFluid(; density = 876, bulk_modulus = 1.2e9)
         mass = T.Mass(;v=dx,m=M,g=-g)
-        vol = Volume(;area=A, x=x₀, p=p_int, dx, drho, dm) # <-- missing Volume component from MTKSL (will be released in new version) 
+        vol = IC.Volume(;area=A, x=x₀, p=p_int, dx, drho, dm) 
         mass_flow = IC.MassFlow(;p_int)
         mass_flow_input = B.TimeVaryingFunction(;f = mass_flow_fun)
     end