SavedValues DifferentialEquations.jl

[markilg]

When using ComponentArrays within parameters for differential equations, saving seems to only preserve the last value of the simulation.

Simple Proportional Control Snippet:

      function motor!(D, u, p, t)
            @unpack J, b, Ke, Kt, R, L, V = p
            @unpack Dθ, θ, i = u
 
            D.Dθ = -b/J*Dθ + Kt/J*i
            D.θ = Dθ
            D.i = -R/L*i - Ke/L*Dθ + 1/L*V
            return nothing
      end

      motor_p = ComponentArray(J=0.01,b=0.1,Ke=0.01,Kt=0.01,R=1.0,L=0.5,V=0.0)

      struct ProportionalController{T}
            Gain::T
      end

      # Controller Feedback - Compare the Error between (1.0 - Step Response and Value)
      function (c::ProportionalController)(integrator::OrdinaryDiffEq.ODEIntegrator)   
            error = 1.0 - integrator.u.Dθ   
            integrator.p.V = c.Gain*error      
      end

      model = ODEProblem(motor!,ComponentArray(Dθ=0.0,θ=0.0,i=0.0),(0.0,1.0),motor_p)

      saved_values = SavedValues(Float64,ComponentArray)
      cb = SavingCallback((u,t,integrator)->(integrator.p), saved_values)

      controller = ProportionalController(10.0)
      controller_cb = PeriodicCallback(controller,0.1; initial_affect = false);

      cbs = CallbackSet(cb,controller_cb)
      sol = solve(model,Tsit5(), callback = cbs)

Here saved_values only has values of V that are constant for the simulation time window.

If you change:

      saved_values = SavedValues(Float64,Float64) 
      cb = SavingCallback((u,t,integrator)->(integrator.p.V), saved_values)

*** EDIT : Disregard this issue. Using a copy operation preserves the values. - Oversight in implementation.

    cb = SavingCallback((u,t,integrator)->(copy(integrator.p)), saved_values)