Merge pull request #110 from JuliaControl/mtk_corr

doc: MTK example throw error for non-strictly proper systems

docs/src/manual/mtk.md

@@ -60,39 +60,61 @@ function generate_f_h(model, inputs, outputs)
  if any(ModelingToolkit.is_alg_equation, equations(io_sys)) 
  error("Systems with algebraic equations are not supported")
  end
- h_ = ModelingToolkit.build_explicit_observed_function(io_sys, outputs; inputs = inputs)
- nx = length(dvs)
+ nu, nx, ny = length(inputs), length(dvs), length(outputs)
  vx = string.(dvs)
- par = varmap_to_vars(defaults(io_sys), psym)
- function f!(ẋ, x, u, _ , _ )
- f_ip(ẋ, x, u, par, 1)
- nothing
+ p = varmap_to_vars(defaults(io_sys), psym)
+ function f!(ẋ, x, u, _ , p)
+ try
+ f_ip(ẋ, x, u, p, nothing)
+ catch err
+ if err isa MethodError
+ error("NonLinModel does not support a time argument t in the f function, "*
+ "see the constructor docstring for a workaround.")
+ else
+ rethrow()
+ end
+ end
+ return nothing
  end
- function h!(y, x, _ , _ )
- y .= h_(x, 1, par, 1)
- nothing
+ h_ = ModelingToolkit.build_explicit_observed_function(io_sys, outputs; inputs)
+ u_nothing = fill(nothing, nu)
+ function h!(y, x, _ , p)
+ y .= try
+ # MTK.jl supports a `u` argument in `h_` function but not this package. We set
+ # `u` as a vector of nothing and `h_` function will presumably throw an
+ # MethodError it this argument is used inside the function
+ h_(x, u_nothing, p, nothing)
+ catch err
+ if err isa MethodError
+ error("NonLinModel only support strictly proper systems (no manipulated "*
+ "input argument u in the output function h)")
+ else
+ rethrow()
+ end
+ end
+ return nothing
  end
- return f!, h!, nx, vx
+ return f!, h!, p, nu, nx, ny, vx
 end
 inputs, outputs = [mtk_model.τ], [mtk_model.y]
-f!, h!, nx, vx = generate_f_h(mtk_model, inputs, outputs)
-nu, ny, Ts = length(inputs), length(outputs), 0.1
+f!, h!, p, nu, nx, ny, vx = generate_f_h(mtk_model, inputs, outputs)
+Ts = 0.1
 vu, vy = ["\$τ\$ (Nm)"], ["\$θ\$ (°)"]
 nothing # hide
 ```
 
 A [`NonLinModel`](@ref) can now be constructed:
 
 ```@example 1
-model = setname!(NonLinModel(f!, h!, Ts, nu, nx, ny); u=vu, x=vx, y=vy)
+model = setname!(NonLinModel(f!, h!, Ts, nu, nx, ny; p); u=vu, x=vx, y=vy)
 ```
 
 We also instantiate a plant model with a 25 % larger friction coefficient ``K``:
 
 ```@example 1
 mtk_model.K = defaults(mtk_model)[mtk_model.K] * 1.25
-f_plant, h_plant, _, _ = generate_f_h(mtk_model, inputs, outputs)
-plant = setname!(NonLinModel(f_plant, h_plant, Ts, nu, nx, ny); u=vu, x=vx, y=vy)
+f_plant, h_plant, p = generate_f_h(mtk_model, inputs, outputs)
+plant = setname!(NonLinModel(f_plant, h_plant, Ts, nu, nx, ny; p); u=vu, x=vx, y=vy)
 ```
 
 ## Controller Design

src/model/linmodel.jl

@@ -150,7 +150,8 @@ function LinModel(
  sysu = sminreal(sys[:,i_u]) # remove states associated to measured disturbances d
  sysd = sminreal(sys[:,i_d]) # remove states associated to manipulates inputs u
  if !iszero(sysu.D)
- error("State matrix D must be 0 for columns associated to manipulated inputs u")
+ error("LinModel only supports strictly proper systems (state matrix D must be 0 "*
+ "for columns associated to manipulated inputs u)")
  end
  if iscontinuous(sys)
  isnothing(Ts) && error("Sample time Ts must be specified if sys is continuous")

src/model/solver.jl

@@ -54,9 +54,9 @@ function get_solver_functions(NT::DataType, solver::RungeKutta, fc!, hc!, Ts, _
  k2 = get_tmp(k2_cache, var)
  k3 = get_tmp(k3_cache, var)
  k4 = get_tmp(k4_cache, var)
+ xterm = xnext
  @. xcur = x
  for i=1:solver.supersample
- xterm = xnext # TODO: move this out of the loop, just above (to test) ?
  @. xterm = xcur
  fc!(k1, xterm, u, d, p)
  @. xterm = xcur + k1 * Ts_inner/2