OpenSourceAWE · ufechner7 · Jul 10, 2025 · Jul 9, 2025 · Jul 9, 2025 · Jul 9, 2025
diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
@@ -133,6 +133,9 @@ jobs:
         shell: bash
       - uses: actions/checkout@v4
       - uses: julia-actions/setup-julia@v2
+      - name: Build PyCall
+        run: julia --project=docs/ -e 'ENV["PYTHON"]=""; using Pkg; Pkg.develop(PackageSpec(path=pwd())); Pkg.instantiate(); Pkg.build("PyCall")'
+        shell: bash
       - uses: julia-actions/cache@v2
       - uses: julia-actions/julia-buildpkg@v1
       - uses: julia-actions/julia-docdeploy@v1

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -2,9 +2,18 @@
 SPDX-FileCopyrightText: 2025 Uwe Fechner, Bart van de Lint
 SPDX-License-Identifier: MIT
 -->
+### Unreleased
+#### Changed
+- rename `init_sim!` to `init!`
+- removed the parameter `upwind_dir!` from `init!`; use set.upwind_dir instead. Careful: This is in degrees.
+- the function `init!` accepts (and ignores) the parameters `delta` and `stiffness_factor` if applied to a 
+  SymbolicAWEModel
+### Added
+- add the test script test_interface.jl
+- add the field `integrator` to KPS4 and KPS3 structs
 
 ### KiteModels v0.8.1 2025-06-20
-#### CHANGED
+#### Changed
 - renamed POWER to POWER_LINE and STEERING to STEERING_LINE
 - improved documentation, fixed example
 

diff --git a/data/settings.yaml b/data/settings.yaml
@@ -11,10 +11,18 @@ system:
     fixed_font: ""                 # name or filepath+filename of alternative fixed pitch font, e.g. Liberation Mono
 
 initial:
-    l_tethers: [150.0, 0, 0]       # initial tether length       [m]
-    elevation: [70.8]              # initial elevation angle   [deg]
-    v_reel_outs: [0.0, 0 ,0]       # initial reel out speed    [m/s]
-    depower:     [25.0]            # initial depower settings    [%]
+    elevations: [70.8]               # initial elevation angle   [deg]
+    elevation_rates: [0.0]           # initial elevation rate  [deg/s]
+    azimuths: [0.0]                  # initial azimuth angle     [deg]
+    azimuth_rates: [0.0]             # initial azimuth rate    [deg/s]
+    headings: [0.0]                  # initial heading angle     [deg]
+    heading_rates: [0.0]             # initial heading rate    [deg/s]
+    # three values are only needed for RamAirKite, for KPS3 and KPS4 use only the first value
+    l_tethers: [150.0]               # initial tether lengths      [m]
+    kite_distances: [51.0]           # initial kite distances     [m]
+    v_reel_outs: [0.0]               # initial reel out speeds   [m/s]
+    depowers: [25.0]                 # initial depower settings    [%]
+    steerings: [0.0]                 # initial steering settings   [%]
 
 solver:
     abs_tol: 0.0006        # absolute tolerance of the DAE solver [m, m/s]

diff --git a/docs/src/examples_4p.md b/docs/src/examples_4p.md
@@ -30,7 +30,7 @@ Then we call the function `find_steady_state` which uses a non-linear solver to
 find_steady_state!(kps, prn=true)
 ```
 Finding the steady state of the 4-point model is difficult and it only works when we artificially reduce the stiffness by a factor
-of 0.035. In the function [`init_sim!`](@ref) this factor is slowly increased to 1.0.
+of 0.035. In the function [`init!`](@ref) this factor is slowly increased to 1.0.
 
 To plot the result in 2D we extract the vectors of the x and z coordinates of the tether particles with a for loop:
 ```julia

diff --git a/docs/src/functions.md b/docs/src/functions.md
@@ -55,7 +55,7 @@ SysState
 
 ## High level simulation interface
 ```@docs
-init_sim!
+init!
 next_step!
 ```
 

diff --git a/docs/src/index.md b/docs/src/index.md
@@ -83,7 +83,7 @@ times faster.
 - the documentation was improved
 
 ## Provides
-The types [`KPS3`](@ref), [`KPS4`](@ref) and [`SymbolicAWEModel`](@ref), representing the one point, the four point kite model and the ram air kite model, together with the high level simulation interface consisting of the functions [`init_sim!`](@ref) and [`next_step!`](@ref). Other kite models can be added inside or outside of this package by implementing the non-generic methods required for an AbstractKiteModel.
+The types [`KPS3`](@ref), [`KPS4`](@ref) and [`SymbolicAWEModel`](@ref), representing the one point, the four point kite model and the ram air kite model, together with the high level simulation interface consisting of the functions [`init!`](@ref) and [`next_step!`](@ref). Other kite models can be added inside or outside of this package by implementing the non-generic methods required for an AbstractKiteModel.
 
 Additional functions to provide inputs and outputs of the model on each time step. In particular the constructor [`SysState`](@ref) can be called once per time step to create a SysState struct for
 logging or for displaying the state in a viewer. For the KPS3 and KPS4 model, once per time step the [`residual!`](@ref) function is called as many times as needed to find the solution at the end

diff --git a/docs/src/tutorial_system_structure.md b/docs/src/tutorial_system_structure.md
@@ -69,7 +69,7 @@ If the system looks good, we can easily model it, by first creating a [`Symbolic
 ```julia
 sam = SymbolicAWEModel(set, sys_struct)
 
-init_sim!(sam; remake=false)
+init!(sam; remake=false)
 for i in 1:80
     plot(sam, i/set.sample_freq)
     next_step!(sam)

diff --git a/examples/bench.jl b/examples/bench.jl
@@ -34,7 +34,7 @@ function simulate(integrator, steps)
     iter / steps
 end
 
-integrator = KiteModels.init_sim!(kps4; delta=0, stiffness_factor=0.5, prn=STATISTIC)
+integrator = KiteModels.init!(kps4; delta=0, stiffness_factor=0.5, prn=STATISTIC)
 
 println("\nStarting simulation...")
 simulate(integrator, 100)

diff --git a/examples/bench_4p.jl b/examples/bench_4p.jl
@@ -52,7 +52,7 @@ function simulate(integrator, steps, offset=0)
     iter / steps
 end
 
-integrator = KiteModels.init_sim!(kps4, delta=0, stiffness_factor=0.5, prn=STATISTIC)
+integrator = KiteModels.init!(kps4, delta=0, stiffness_factor=0.5, prn=STATISTIC)
 
 println("\nStarting simulation...")
 simulate(integrator, 100, 100)

diff --git a/examples/calc_spectrum.jl b/examples/calc_spectrum.jl
@@ -100,7 +100,7 @@ function sim_and_plot(set; depower=DEPOWER, f_ex)
     set.elevation = 67.0
     kcu::KCU = KCU(set)
     kps4::KPS4 = KPS4(kcu)
-    integrator = KiteModels.init_sim!(kps4; delta=0.001*0, stiffness_factor=1, prn=STATISTIC)
+    integrator = KiteModels.init!(kps4; delta=0.001*0, stiffness_factor=1, prn=STATISTIC)
     set_depower_steering(kps4.kcu, depower, 0.0)
     simulate(kps4, integrator, logger, STEPS, f_ex)
     save_log(logger, "tmp")

diff --git a/examples/compare_kps3_kps4.jl b/examples/compare_kps3_kps4.jl
@@ -55,7 +55,7 @@ function simulate(s, integrator, steps, plot=false; fig="")
     iter / steps
 end
 
-integrator = KiteModels.init_sim!(kps3, delta=0.001, stiffness_factor=0.5, prn=STATISTIC)
+integrator = KiteModels.init!(kps3, delta=0.001, stiffness_factor=0.5, prn=STATISTIC)
 av_steps = simulate(kps3, integrator, STEPS, true; fig="kps3")
 
 lift, drag = KiteModels.lift_drag(kps3)
@@ -65,7 +65,7 @@ println("winch_force [N]: $(round(winch_force(kps3), digits=2))")
 println("Average number of callbacks per time step: $(round(av_steps, digits=2))")
 
 kps4.set.alpha_zero = ALPHA_ZERO
-integrator = KiteModels.init_sim!(kps4; delta=0.001, stiffness_factor=1, prn=STATISTIC)
+integrator = KiteModels.init!(kps4; delta=0.001, stiffness_factor=1, prn=STATISTIC)
 av_steps = simulate(kps4, integrator, STEPS, true; fig="kps4")
 
 lift, drag = KiteModels.lift_drag(kps4)

diff --git a/examples/initial_reel_out_4p.jl b/examples/initial_reel_out_4p.jl
@@ -69,7 +69,7 @@ function simulate(integrator, steps, plot=false)
     iter / steps
 end
 
-integrator = KiteModels.init_sim!(kps4; delta=0.000, stiffness_factor=0.25, prn=STATISTIC)
+integrator = KiteModels.init!(kps4; delta=0.000, stiffness_factor=0.25, prn=STATISTIC)
 kps4.sync_speed = set.v_reel_out
 
 if PLOT

diff --git a/examples/initial_reel_out_4p_torque_control.jl b/examples/initial_reel_out_4p_torque_control.jl
@@ -89,7 +89,7 @@ end
 
 kps4.sync_speed = set.v_reel_out
 kps4.wm.last_set_speed = set.v_reel_out
-integrator = KiteModels.init_sim!(kps4; delta=0.00015, stiffness_factor=0.8, prn=STATISTIC)
+integrator = KiteModels.init!(kps4; delta=0.00015, stiffness_factor=0.8, prn=STATISTIC)
 
 if PLOT
     av_steps = simulate(integrator, STEPS, true)

diff --git a/examples/lin_ram_model.jl b/examples/lin_ram_model.jl
@@ -61,7 +61,7 @@ lin_outputs = @variables heading(t_nounits)[1]
 # Initialize at elevation with linearization outputs
 s.sys_struct.winches[2].tether_length += 0.2
 s.sys_struct.winches[3].tether_length += 0.2
-KiteModels.init_sim!(s; 
+KiteModels.init!(s; 
     remake=false,
     reload=true,
     lin_outputs  # Specify which outputs to track in linear model

diff --git a/examples/plot_alpha2.jl b/examples/plot_alpha2.jl
@@ -57,7 +57,7 @@ function simulate(integrator, steps, offset=0)
     iter / steps
 end
 
-integrator = KiteModels.init_sim!(kps4, stiffness_factor=0.5, prn=STATISTIC)
+integrator = KiteModels.init!(kps4, stiffness_factor=0.5, prn=STATISTIC)
 
 println("\nStarting simulation...")
 simulate(integrator, 100, 100)

diff --git a/examples/plot_cl_cd.jl b/examples/plot_cl_cd.jl
@@ -97,7 +97,7 @@ for depower in DEPOWER
 
     kcu = KCU(set)
     kps4 = KPS4(kcu)
-    integrator = KiteModels.init_sim!(kps4; delta=0.03, stiffness_factor=0.05, prn=STATISTIC)
+    integrator = KiteModels.init!(kps4; delta=0.03, stiffness_factor=0.05, prn=STATISTIC)
     if ! isnothing(integrator)
         try
             cl, cd = simulate(kps4, integrator, logger, STEPS)

diff --git a/examples/plot_parking_test.jl b/examples/plot_parking_test.jl
@@ -115,7 +115,7 @@ for depower in DEPOWER
     kps4::KPS4 = KPS4(kcu)
     set.elevation += 5
     set.v_wind = V_WIND_200[i] / 1.348881340489221 * calc_wind_factor(kps4.am, HEIGHT[i])/1.348881340489221
-    integrator = KiteModels.init_sim!(kps4; delta=0.001*0, stiffness_factor=1, prn=STATISTIC)
+    integrator = KiteModels.init!(kps4; delta=0.001*0, stiffness_factor=1, prn=STATISTIC)
     if ! isnothing(integrator)
         try
             cl, cd = simulate(kps4, integrator, logger, STEPS)

diff --git a/examples/plot_pitch_stability.jl b/examples/plot_pitch_stability.jl
@@ -110,7 +110,7 @@ kcu::KCU = KCU(set)
 kps4::KPS4 = KPS4(kcu)
 set.elevation += 5
 set.v_wind = V_WIND_200
-integrator = KiteModels.init_sim!(kps4; delta=0.001*0, stiffness_factor=1, prn=STATISTIC)
+integrator = KiteModels.init!(kps4; delta=0.001*0, stiffness_factor=1, prn=STATISTIC)
 if ! isnothing(integrator)
     simulate(kps4, integrator, logger, STEPS)
     set_depower_steering(kps4.kcu, depower, 0.0)

diff --git a/examples/plot_side_cl.jl b/examples/plot_side_cl.jl
@@ -81,10 +81,10 @@ STEERING = zeros(length(SET_STEERING))
 SIDE_CL  = zeros(length(SET_STEERING))
 for (i, set_steering) in pairs(SET_STEERING)
     local side_cl, integrator
-    integrator = KiteModels.init_sim!(kps4;  delta=0.001, stiffness_factor=1, prn=STATISTIC)
+    integrator = KiteModels.init!(kps4;  delta=0.001, stiffness_factor=1, prn=STATISTIC)
     side_cl, steering = simulate(integrator, STEPS, set_steering, plot=false)
     if side_cl == 0.0
-        integrator = KiteModels.init_sim!(kps4;  delta=0.001, stiffness_factor=1, prn=STATISTIC)
+        integrator = KiteModels.init!(kps4;  delta=0.001, stiffness_factor=1, prn=STATISTIC)
         side_cl, steering = simulate(integrator, STEPS, set_steering, plot=false)
     end
     SIDE_CL[i] = side_cl

diff --git a/examples/ram_air_kite.jl b/examples/ram_air_kite.jl
@@ -49,7 +49,7 @@ toc()
 # Initialize at elevation
 set.l_tethers[2] += 0.2
 set.l_tethers[3] += 0.2
-init_sim!(sam; remake=false, reload=false)
+init!(sam; remake=false, reload=false)
 sys = sam.sys
 
 @info "System initialized at:"

diff --git a/examples/reel_out_1p.jl b/examples/reel_out_1p.jl
@@ -61,7 +61,7 @@ function simulate(integrator, steps, plot=false)
     iter / steps
 end
 
-integrator = KiteModels.init_sim!(kps3, delta=0, stiffness_factor=0.04, prn=STATISTIC)
+integrator = KiteModels.init!(kps3, delta=0, stiffness_factor=0.04, prn=STATISTIC)
 kps3.sync_speed = 0.0
 
 if PLOT

diff --git a/examples/reel_out_4p.jl b/examples/reel_out_4p.jl
@@ -66,7 +66,7 @@ function simulate(integrator, steps, plot=false)
     iter / steps
 end
 
-integrator = KiteModels.init_sim!(kps4; delta=0, stiffness_factor=1, prn=STATISTIC)
+integrator = KiteModels.init!(kps4; delta=0, stiffness_factor=1, prn=STATISTIC)
 kps4.sync_speed = 0.0
 
 if PLOT

diff --git a/examples/reel_out_4p_torque_control.jl b/examples/reel_out_4p_torque_control.jl
@@ -70,7 +70,7 @@ function simulate(integrator, steps, plot=false)
     iter / steps
 end
 
-integrator = KiteModels.init_sim!(kps4; delta=0, stiffness_factor=1, prn=STATISTIC)
+integrator = KiteModels.init!(kps4; delta=0, stiffness_factor=1, prn=STATISTIC)
 kps4.sync_speed = 0.0
 
 if PLOT

diff --git a/examples/simulate_simple.jl b/examples/simulate_simple.jl
@@ -62,8 +62,8 @@ function simulate(integrator, steps, plot=false)
     end
     iter / steps
 end
-
-integrator = KiteModels.init_sim!(kps4;  delta=0.0, stiffness_factor=1, upwind_dir=UPWIND_DIR, prn=STATISTIC)
+kps4.set.upwind_dir = rad2deg(UPWIND_DIR)
+integrator = KiteModels.init!(kps4;  delta=0.0, stiffness_factor=1, prn=STATISTIC)
 
 if PLOT
     global flight_log

diff --git a/examples/simulate_steering.jl b/examples/simulate_steering.jl
@@ -64,7 +64,7 @@ function simulate(integrator, steps, plot=false)
     iter / steps
 end
 
-integrator = KiteModels.init_sim!(kps3; delta=0, stiffness_factor=0.04, prn=STATISTIC)
+integrator = KiteModels.init!(kps3; delta=0, stiffness_factor=0.04, prn=STATISTIC)
 
 if PLOT
     av_steps = simulate(integrator, STEPS, true)

diff --git a/examples/steering_test_1p.jl b/examples/steering_test_1p.jl
@@ -99,7 +99,7 @@ function simulate(integrator, steps; plot=false)
     end
 end
 
-integrator = KiteModels.init_sim!(kps3;  delta=0.0, stiffness_factor=1, prn=STATISTIC)
+integrator = KiteModels.init!(kps3;  delta=0.0, stiffness_factor=1, prn=STATISTIC)
 simulate(integrator, STEPS; plot=true)
 
 function delay(x, y, t_max = 10)

diff --git a/examples/steering_test_4p.jl b/examples/steering_test_4p.jl
@@ -104,7 +104,7 @@ function simulate(integrator, steps; plot=false)
 end
 
 
-integrator = KiteModels.init_sim!(kps4;  delta=0.0, stiffness_factor=1, prn=STATISTIC)
+integrator = KiteModels.init!(kps4;  delta=0.0, stiffness_factor=1, prn=STATISTIC)
 simulate(integrator, STEPS; plot=true)
 
 function delay(x, y, t_max = 10)

diff --git a/examples/test_init_1p.jl b/examples/test_init_1p.jl
@@ -38,7 +38,7 @@ logger = Logger(set.segments + 1, STEPS)
 
 kcu::KCU = KCU(set)
 kps3::KPS3 = KPS3(kcu)
-integrator = KiteModels.init_sim!(kps3; delta=0.03, stiffness_factor=0.1, prn=STATISTIC)
+integrator = KiteModels.init!(kps3; delta=0.03, stiffness_factor=0.1, prn=STATISTIC)
 lift, drag = lift_drag(kps3)
 sys_state = KiteModels.SysState(kps3)
 log!(logger, sys_state)

diff --git a/examples/test_init_4p.jl b/examples/test_init_4p.jl
@@ -39,7 +39,7 @@ logger = Logger(set.segments + 5, STEPS)
 
 kcu::KCU = KCU(set)
 kps4::KPS4 = KPS4(kcu)
-integrator = KiteModels.init_sim!(kps4; delta=0.03, stiffness_factor=0.01, upwind_dir=UPWIND_DIR, prn=STATISTIC)
+integrator = KiteModels.init!(kps4; delta=0.03, stiffness_factor=0.01, upwind_dir=UPWIND_DIR, prn=STATISTIC)
 for i=1:80
     next_step!(kps4, integrator; set_speed=kps4.set.v_reel_out, dt)
 end

diff --git a/examples/test_steady_state.jl b/examples/test_steady_state.jl
@@ -12,7 +12,7 @@ kps4::KPS4 = KPS4(kcu)
 
 clear!(kps4)
 KiteModels.set_depower_steering!(kps4, kps4.set.depower_offset/100.0, 0.0)
-@time KiteModels.init_sim!(kps4; delta=0.001, stiffness_factor=0.5, prn=false)
+@time KiteModels.init!(kps4; delta=0.001, stiffness_factor=0.5, prn=false)
 
 println("\nlift, drag    [N]  : $(KiteModels.lift_drag(kps4))")
 println("\nSpring forces:")

diff --git a/examples/tether.jl b/examples/tether.jl
@@ -30,7 +30,7 @@ plot(sys_struct, 0.0)
 
 sam = SymbolicAWEModel(set, sys_struct)
 
-init_sim!(sam; remake=false)
+init!(sam; remake=false)
 for i in 1:80
     plot(sam, i/set.sample_freq)
     next_step!(sam)

diff --git a/examples_3d/parking_4p.jl b/examples_3d/parking_4p.jl
@@ -85,7 +85,7 @@ function simulate(integrator, steps, plot=PLOT)
     iter / steps
 end
 
-integrator = KiteModels.init_sim!(kps4, delta=0, stiffness_factor=0.5, prn=STATISTIC)
+integrator = KiteModels.init!(kps4, delta=0, stiffness_factor=0.5, prn=STATISTIC)
 
 println("\nStarting simulation...")
 simulate(integrator, STEPS)

diff --git a/mwes/mwe_01.jl b/mwes/mwe_01.jl
@@ -6,5 +6,5 @@ using KiteModels
 
 kps4::KPS4 = KPS4(KCU(se()))
 
-integrator = KiteModels.init_sim!(kps4; stiffness_factor=0.035, prn=false)
+integrator = KiteModels.init!(kps4; stiffness_factor=0.035, prn=false)
 nothing
diff --git a/mwes/mwe_02.jl b/mwes/mwe_02.jl
@@ -11,7 +11,7 @@ set.solver="DFBDF"
 kps4::KPS4 = KPS4(KCU(set))
 STEPS = 200
 
-integrator = KiteModels.init_sim!(kps4; stiffness_factor=0.035, prn=false)
+integrator = KiteModels.init!(kps4; stiffness_factor=0.035, prn=false)
 next_step!(kps4, integrator, set_speed = 0, dt=0.05)
 @timev next_step!(kps4, integrator; set_speed = 0, dt=0.05)
 function nsteps(kps4, integrator)

diff --git a/mwes/mwe_10.jl b/mwes/mwe_10.jl
@@ -6,5 +6,5 @@ using KiteModels
 
 kps4_3L::SymbolicAWEModel = SymbolicAWEModel(KCU(se()))
 
-integrator = KiteModels.init_sim!(kps4_3L; stiffness_factor=0.035, prn=false)
+integrator = KiteModels.init!(kps4_3L; stiffness_factor=0.035, prn=false)
 nothing
diff --git a/mwes/mwe_11.jl b/mwes/mwe_11.jl
@@ -15,5 +15,5 @@ kps3::KPS3 = KPS3(kcu)
 
 
 reltime = 0.0
-integrator = KiteModels.init_sim!(kps3, stiffness_factor=0.04)
+integrator = KiteModels.init!(kps3, stiffness_factor=0.04)
 plot2d(kps3.pos, reltime; zoom=false, front=false, segments=set.segments)
diff --git a/mwes/mwe_11b.jl b/mwes/mwe_11b.jl
@@ -14,5 +14,5 @@ kcu::KCU = KCU(set)
 kps4::KPS4 = KPS4(kcu)
 
 reltime = 0.0
-integrator = KiteModels.init_sim!(kps4, stiffness_factor=0.5)
+integrator = KiteModels.init!(kps4, stiffness_factor=0.5)
 plot2d(kps4.pos, reltime; zoom=true, front=false, segments=set.segments)
diff --git a/mwes/mwe_12.jl b/mwes/mwe_12.jl
@@ -15,5 +15,5 @@ kcu::KCU = KCU(set)
 kps3::KPS3 = KPS3(kcu)
 
 reltime = 0.0
-integrator = KiteModels.init_sim!(kps3, stiffness_factor=0.04)
+integrator = KiteModels.init!(kps3, stiffness_factor=0.04)
 plot2d(kps3.pos, reltime; zoom=false, front=false, segments=set.segments)
diff --git a/mwes/mwe_12b.jl b/mwes/mwe_12b.jl
@@ -15,7 +15,7 @@ kcu::KCU = KCU(set)
 kps4::KPS4 = KPS4(kcu)
 
 reltime = 0.0
-integrator = KiteModels.init_sim!(kps4, stiffness_factor=0.5)
+integrator = KiteModels.init!(kps4, stiffness_factor=0.5)
 
 lines, sc, txt = nothing, nothing, nothing
 plot2d(kps4.pos, reltime; zoom=true, front=false, segments=set.segments, lines, sc, txt)

diff --git a/mwes/mwe_26.jl b/mwes/mwe_26.jl
@@ -13,7 +13,7 @@ set.v_wind = 50
 kps4::KPS4 = KPS4(KCU(set))
 STEPS = 200
 
-integrator = KiteModels.init_sim!(kps4; stiffness_factor=0.5, prn=false)
+integrator = KiteModels.init!(kps4; stiffness_factor=0.5, prn=false)
 
 next_step!(kps4, integrator, set_speed = 0, dt=0.05)
 function nsteps(kps4, integrator)