default initial value for quaternion

Author: baggepinnen

src/orientation.jl

@@ -437,7 +437,7 @@ end
 
 function nonunit_quaternion_equations(R, w)
     @variables Q(t)[1:4], [state_priority=-1, description="Unit quaternion with [w,i,j,k]"] # normalized
-    @variables Q̂(t)[1:4], [state_priority=1000, description="Non-unit quaternion with [w,i,j,k]"] # Non-normalized
+    @variables Q̂(t)[1:4]=[1,0,0,0], [state_priority=1000, description="Non-unit quaternion with [w,i,j,k]"] # Non-normalized
     @variables Q̂d(t)[1:4], [state_priority=1000]
     # NOTE: 
     @variables n(t) c(t)

test/test_PlanarMechanics.jl

@@ -615,11 +615,10 @@ end
 end
 
 @named model = TwoTrackWithDifferentialGear()
-model = complete(model)
-ssys = structural_simplify(IRSystem(model))
+ssys = multibody(model)
 defs = merge(
-    Dict(unknowns(ssys) .=> 0),
-    ModelingToolkit.defaults(model),
+    # Dict(unknowns(ssys)[ModelingToolkit.is_diff_equation.(equations(ssys))] .=> 0),
+    # ModelingToolkit.defaults(model),
     Dict(model.body.w => 0),
 )
 prob = ODEProblem(ssys, defs, (0.0, 20.0))