diff --git a/examples/robot/test_components.jl b/examples/robot/test_components.jl
index e9dca2f6..0f3b6f87 100644
--- a/examples/robot/test_components.jl
+++ b/examples/robot/test_components.jl
@@ -97,39 +97,42 @@ myinertia(args...; kwargs...) = ModelingToolkitStandardLibrary.Mechanical.Rotati
 
 mytorque(args...; kwargs...) = ModelingToolkitStandardLibrary.Mechanical.Rotational.ConstantTorque(args...; kwargs...)
 
-@mtkmodel AxisTest begin
+@mtkmodel AxisTest2 begin
     @components begin
         axis2 = AxisType2()
-        # fixed = myfixed() # bug in @mtkmodel
-        fixed = mytorque(tau_constant=1, use_support=false) # bug in @mtkmodel
+        fixed = myfixed() # bug in @mtkmodel
+        # fixed = mytorque(tau_constant=1, use_support=true) # bug in @mtkmodel
         # inertia = myinertia(J=1)
         # constant1 = Constant(k=1)
-        constant2 = Constant(k=1)
+        constant2 = Constant(k=0)
         constant3 = Constant(k=1)
         constant4 = Constant(k=1)
-        constant5 = Constant(k=1)
-
-        constant6 = Constant(k=1)
-        constant7 = Constant(k=1)
-        constant8 = Constant(k=1)
-        constant9 = Constant(k=1)
-        constant10 = Constant(k=1)
-
+        constant5 = Constant(k=0)
     end
     @equations begin
         connect(axis2.flange, fixed.flange)
         # connect(axis2.flange, inertia.flange_a)
         # constant1.output.u ~ motor.axisControlBus.current_ref # This is connected to the controller output
-        constant2.output.u ~ motor.axisControlBus.speed_ref
-        constant3.output.u ~ motor.axisControlBus.angle_ref
-        constant4.output.u ~ motor.axisControlBus.motion_ref
-        constant5.output.u ~ motor.axisControlBus.acceleration_ref
+        constant2.output.u ~ axis2.axisControlBus.speed_ref
+        constant3.output.u ~ axis2.axisControlBus.angle_ref
+        constant4.output.u ~ axis2.axisControlBus.motion_ref
+        constant5.output.u ~ axis2.axisControlBus.acceleration_ref
     end
 end
 
-@named axisTest = AxisTest()
+@named axisTest = AxisTest2()
 m = structural_simplify(axisTest)
-m = structural_simplify(IRSystem(axisTest))
+# m = structural_simplify(IRSystem(axisTest)) # Yingbo: solution unstable with IRSystem simplification
+
+cm = complete(axisTest)
+prob = ODEProblem(m, [
+    D(D(cm.axis2.gear.gear.phi_b)) => 0
+], (0.0, 5))
+sol = solve(prob, Rodas4())
+@test SciMLBase.successful_retcode(sol)
+plot(sol, layout=length(states(m)))
+u = cm.axis2.controller.PI.ctr_output.u
+@test abs(sol(prob.tspan[2], idxs=u)) < 1e-6
 
 ##
 
@@ -142,7 +145,6 @@ m = structural_simplify(IRSystem(axisTest))
 @named pp = PathPlanning1(;)
 @named pp6 = PathPlanning6(;)
 
-@named oneaxis = OneAxis()
 @named oneaxis = OneAxis()
 
 ssys = structural_simplify(IRSystem(oneaxis))
diff --git a/examples/robot/utilities/components.jl b/examples/robot/utilities/components.jl
index 6a2e3ee9..5d9d159e 100644
--- a/examples/robot/utilities/components.jl
+++ b/examples/robot/utilities/components.jl
@@ -102,11 +102,9 @@ function AxisType2(; name, kp = 10, ks = 1, Ts = 0.01, k = 1.1616, w = 4590, D =
         axisControlBus = AxisControlBus()
     end
 
-    eqs = [connect(gear.flange_b, flange)
-           connect(gear.flange_b, angleSensor.flange)
-           connect(gear.flange_b, speedSensor.flange)
+    eqs = [
+           connect(gear.flange_b, flange, angleSensor.flange, speedSensor.flange, accSensor.flange)
            connect(motor.flange_motor, gear.flange_a)
-           connect(gear.flange_b, accSensor.flange)
            connect(motor.axisControlBus, axisControlBus)
            (angleSensor.phi.u ~ axisControlBus.angle)
            (speedSensor.w.u ~ axisControlBus.speed)
diff --git a/test/runtests.jl b/test/runtests.jl
index 5910e498..a66d6aff 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -220,7 +220,7 @@ connections = [connect(world.frame_b, rev.frame_a)
 modele = ModelingToolkit.expand_connections(model)
 
 # ssys = structural_simplify(model)#, allow_parameter = false)
-ssys = structural_simplify(IRSystem(modele)) # Yingbo, this fails with SymbolicIR but not with MTK
+ssys = structural_simplify(IRSystem(modele)) # Yingbo, Rotation-matrix dummy derivatives
 
 D = Differential(t)
 
@@ -744,7 +744,8 @@ eqs = [connect(world.frame_b, gearConstraint.bearing)
 
 
 # @test_skip begin
-    ssys = structural_simplify(IRSystem(model)) # Index out of bounds, Yingbo
+    ssys = structural_simplify(model) # Yingbo: Sym doesn't have a operation or arguments! 
+    ssys = structural_simplify(IRSystem(model)) # Yingbo: Not a well formed derivative expression
 
     prob = ODEProblem(ssys,
                       [
@@ -826,7 +827,7 @@ eqs = [connect(world.frame_b, freeMotion.frame_a)
 # ssys = structural_simplify(model, allow_parameters = false)
 ssys = structural_simplify(IRSystem(model))
 
-# Can't get initial condition to bite, Yingbo
+# Yingbo: acceleration dummy derivatives
 prob = ODEProblem(ssys,
                   [
                     freeMotion.v_rel_a .=> [0,1,0] # Movement in y direction