refactor: describe x as the state; pass name to SystemModel; `p…

…hi_rel0` defaults to 0.0 instead of guessing.

src/Blocks/continuous.jl

@@ -15,12 +15,12 @@ Initial value of integrator state ``x`` can be set with `x`
 
 # Unknowns:
 
-  - `x`: Unknown of Integrator (with initial guess of 0.0)
+  - `x`: State of Integrator (with initial guess of 0.0)
 """
 @mtkmodel Integrator begin
     @extend u, y = siso = SISO()
     @variables begin
-        x(t), [description = "Unknown of Integrator", guess = 0.0]
+        x(t), [description = "State of Integrator", guess = 0.0]
     end
     @parameters begin
         k = 1, [description = "Gain"]
@@ -30,6 +30,7 @@ Initial value of integrator state ``x`` can be set with `x`
         y ~ x
     end
 end
+
 """
     Derivative(; name, k = 1, T, x = 0.0)
 

src/Mechanical/Rotational/components.jl

@@ -86,7 +86,7 @@ Linear 1D rotational spring
 # Parameters:
 
   - `c`: [`N.m/rad`] Spring constant
-  - `phi_rel0`: [`rad`] Unstretched spring angle
+  - `phi_rel0`: [`rad`] Unstretched spring angle. Defaults to 0.0.
 """
 @mtkmodel Spring begin
     @extend phi_rel, tau = partial_comp = PartialCompliant()
@@ -156,7 +156,7 @@ Linear 1D rotational spring and damper
 
   - `d`: [`N.m.s/rad`] Damping constant
   - `c`: [`N.m/rad`] Spring constant
-  - `phi_rel0`: [`rad`] Unstretched spring angle
+  - `phi_rel0`: [`rad`] Unstretched spring angle. Defaults to 0.0
 """
 @mtkmodel SpringDamper begin
     @extend phi_rel, w_rel, tau = partial_comp = PartialCompliantWithRelativeStates()
@@ -167,7 +167,7 @@ Linear 1D rotational spring and damper
     @parameters begin
         d, [description = "Damping constant"]
         c, [description = "Spring constant"]
-        phi_rel0, [description = "Unstretched spring angle", guess = 0.0]
+        phi_rel0 = 0.0, [description = "Unstretched spring angle"]
     end
     @equations begin
         tau_c ~ c * (phi_rel - phi_rel0)

test/Blocks/test_analysis_points.jl

@@ -174,7 +174,8 @@ function SystemModel(u = nothing; name = :model)
                 spring,
                 damper,
                 u
-            ])
+            ],
+            name)
     end
     ODESystem(eqs, t; systems = [torque, inertia1, inertia2, spring, damper], name)
 end