Merge pull request #113 from OpenSourceAWE/steady-torque

Add calc steady torque function and remove WinchModels dependency

Author: 1-Bart-1

.github/workflows/CI.yml

@@ -27,7 +27,7 @@ jobs:
         run: |
           docker run --rm --volume ${{ github.workspace }}:/data fsfe/reuse lint
 
-  test:
+  test-with-code-coverage:
     name: Julia ${{ matrix.version }} - ${{ matrix.os }} - ${{ matrix.arch }} - ${{ github.event_name }}
     runs-on: ${{ matrix.os }}
     timeout-minutes: 120
@@ -86,41 +86,6 @@ jobs:
           if-no-files-found: ignore
           retention-days: 7
 
-  test-with-code-coverage:
-    name: Julia 1.11 - ubuntu-latest - x64 - with code coverage
-    runs-on: ubuntu-latest
-    timeout-minutes: 120
-    steps:
-      - name: Checkout code
-        uses: actions/checkout@v5
-        with:
-          ref: ${{ github.event.client_payload.ref || github.head_ref || github.ref }}
-
-      - name: Copy default Manifest files
-        run: |
-          cp Manifest-v1.11.toml.default Manifest.toml || 
-                echo "No default available for Manifest-v1.11.toml"
-        shell: bash
-
-      - name: Install matplotlib
-        run: sudo apt-get install -y python3-matplotlib
-        shell: bash
-
-      - uses: julia-actions/setup-julia@v2
-        with:
-          version: '1.11'
-          arch: x64
-
-      - uses: julia-actions/cache@v2
-      
-      - uses: julia-actions/julia-buildpkg@v1
-
-      - name: Build PyCall
-        run: julia --project -e 'ENV["SAM_PRECOMPILE"]="false"; ENV["PYTHON"]=""; using Pkg; Pkg.instantiate(); Pkg.add("PyCall"); Pkg.build("PyCall")'
-        shell: bash
-
-      - uses: julia-actions/julia-runtest@v1
-
       - uses: julia-actions/julia-processcoverage@v1
 
       - uses: codecov/codecov-action@v5

docs/src/exported_types.md

@@ -56,7 +56,8 @@ Pulley(idx, segment_idxs, type)
 Tether
 Tether(idx, segment_idxs, winch_idx)
 Winch
-Winch(idx, model, tether_idxs; tether_len, tether_vel, brake)
+Winch(idx, set::Settings, tether_idxs; tether_len, tether_vel, brake)
+Winch(idx, tether_idxs, gear_ratio, drum_radius, f_coulomb, c_vf, inertia_total; tether_len, tether_vel, brake)
 Wing
 Wing(idx, vsm_aero, vsm_wing, vsm_solver, group_idxs, R_b_c, pos_cad; transform_idx)
 Transform

docs/src/private_functions.md

@@ -37,14 +37,13 @@ SymbolicAWEModels.get_sys_struct_hash
 ## Physics and Geometry Helpers
 
 ```@docs
-SymbolicAWEModels.calc_speed_acc
-SymbolicAWEModels.calc_moment_acc
 SymbolicAWEModels.calc_angle_of_attack
 SymbolicAWEModels.calc_heading
 SymbolicAWEModels.calc_R_t_w
 SymbolicAWEModels.calc_R_v_w
 SymbolicAWEModels.cad_to_body_frame
 SymbolicAWEModels.calc_pos
+SymbolicAWEModels.calc_steady_torque
 SymbolicAWEModels.find_axis_point
 SymbolicAWEModels.quaternion_to_rotation_matrix
 SymbolicAWEModels.rotation_matrix_to_quaternion

docs/src/tutorial_system_structure.md

@@ -91,12 +91,12 @@ set.v_wind = 0.0
 tethers = [Tether(1,[segment.idx for segment in segments])]
 ```
 As you can see, we just add all of the segments from the simple tether to our [`Tether`](@ref) struct.
-The next step is to create a winch. Each winch can be connected to one or more tethers, so it is possible to connect multiple tethers to the same winch. We have to specify which kind of winch we want to use. For now, only the `TorqueControlledMachine` from `WinchModels.jl` is supported.
+The next step is to create a winch. Each winch can be connected to one or more tethers, so it is possible to connect multiple tethers to the same winch.
+The winch is a torque controlled winch.
 
 ```julia
 using WinchModels
-wm = TorqueControlledMachine(set)
-winches = [Winch(1, wm, [1])]
+winches = [Winch(1, set, [1])]
 ```
 
 The 2d plot of the [`SystemStructure`](@ref) should still look the same, so we don't have to plot that. We can just create the system, and simulate it. We just need to be sure that we call plot with `t=0.0` to reset the plot.

examples/ram_air_kite.jl

@@ -29,7 +29,7 @@ sam = SymbolicAWEModel(set)
 SymbolicAWEModels.init!(sam)
 
 find_steady_state!(sam)
-bias = 0.15
+bias = 0.2
 if set.physical_model == "4_attach_ram"
     bias = 0.05
 end

src/generate_system.jl

@@ -3,24 +3,6 @@
 
 # Implementation of the ram air wing model using ModelingToolkit.jl
 
-"""
-    calc_speed_acc(winch::AsyncMachine, tether_vel, norm_, set_speed)
-
-Calculate winch acceleration for a speed-controlled asynchronous machine model.
-"""
-function calc_speed_acc(winch::AsyncMachine, tether_vel, norm_, set_speed)
-    calc_acceleration(winch, tether_vel, norm_; set_speed, set_torque=nothing, use_brake=false) # TODO: add brake setting
-end
-
-"""
-    calc_moment_acc(winch::TorqueControlledMachine, tether_vel, norm_, set_torque)
-
-Calculate winch acceleration for a torque-controlled machine model.
-"""
-function calc_moment_acc(winch::TorqueControlledMachine, tether_vel, norm_, set_torque)
-    calc_acceleration(winch, tether_vel, norm_; set_speed=nothing, set_torque, use_brake=false)
-end
-
 """
     calc_angle_of_attack(va_wing_b)
 
@@ -184,6 +166,17 @@ get_fix_point_sphere(sys::SystemStructure, idx::Int16) = sys.points[idx].fix_sph
 get_fix_wing_sphere(sys::SystemStructure, idx::Int16) = sys.wings[idx].fix_sphere
 @register_symbolic get_fix_wing_sphere(sys::SystemStructure, idx::Int16)
 
+get_winch_gear_ratio(sys::SystemStructure, idx::Int16) = sys.winches[idx].gear_ratio
+@register_symbolic get_winch_gear_ratio(sys::SystemStructure, idx::Int16)
+get_winch_drum_radius(sys::SystemStructure, idx::Int16) = sys.winches[idx].drum_radius
+@register_symbolic get_winch_drum_radius(sys::SystemStructure, idx::Int16)
+get_winch_f_coulomb(sys::SystemStructure, idx::Int16) = sys.winches[idx].f_coulomb
+@register_symbolic get_winch_f_coulomb(sys::SystemStructure, idx::Int16)
+get_winch_c_vf(sys::SystemStructure, idx::Int16) = sys.winches[idx].c_vf
+@register_symbolic get_winch_c_vf(sys::SystemStructure, idx::Int16)
+get_winch_inertia_total(sys::SystemStructure, idx::Int16) = sys.winches[idx].inertia_total
+@register_symbolic get_winch_inertia_total(sys::SystemStructure, idx::Int16)
+
 get_set_mass(set::Settings) = set.mass
 @register_symbolic get_set_mass(set::Settings)
 get_rho_tether(set::Settings) = set.rho_tether
@@ -632,6 +625,12 @@ function force_eqs!(s, system, psys, pset, eqs, defaults, guesses;
         winch_force(t)[eachindex(winches)]
         winch_force_vec(t)[1:3, eachindex(winches)]
         brake(t)[eachindex(winches)]
+        # New symbolic variables for winch dynamics
+        ω_motor(t)[eachindex(winches)]
+        tau_friction(t)[eachindex(winches)]
+        tau_motor(t)[eachindex(winches)]
+        tau_total(t)[eachindex(winches)]
+        α_motor(t)[eachindex(winches)]
     end
     for winch in winches
         F = zeros(Num, 3)
@@ -641,6 +640,18 @@ function force_eqs!(s, system, psys, pset, eqs, defaults, guesses;
                 error("Point number $winch_idx does not exist.")
             F .+= point_force[:, winch_idx]
         end
+        
+        gear_ratio    = get_winch_gear_ratio(psys, winch.idx)
+        drum_radius   = get_winch_drum_radius(psys, winch.idx)
+        f_coulomb     = get_winch_f_coulomb(psys, winch.idx)
+        c_vf          = get_winch_c_vf(psys, winch.idx)
+        inertia_total = get_winch_inertia_total(psys, winch.idx)
+
+        function smooth_sign(x)
+            EPSILON = 6
+            x / sqrt(x * x + EPSILON * EPSILON)
+        end
+
         eqs = [
             eqs
             brake[winch.idx] ~ get_brake(psys, winch.idx)
@@ -649,11 +660,18 @@ function force_eqs!(s, system, psys, pset, eqs, defaults, guesses;
             D(tether_vel[winch.idx]) ~ ifelse(brake[winch.idx]==true,
                                               0, tether_acc[winch.idx])
 
-            tether_acc[winch.idx] ~ calc_moment_acc( # TODO: moment and speed control
-                winch.model, tether_vel[winch.idx], 
-                winch_force[winch.idx], 
-                set_values[winch.idx]
-            )
+            # Symbolic winch dynamics equations
+            ω_motor[winch.idx] ~ gear_ratio / drum_radius * tether_vel[winch.idx]
+            tau_friction[winch.idx] ~ smooth_sign(ω_motor[winch.idx]) *
+                                      f_coulomb * drum_radius / gear_ratio +
+                                      c_vf * ω_motor[winch.idx] * drum_radius^2 / gear_ratio^2
+            tau_motor[winch.idx] ~ set_values[winch.idx] # set_value is the motor torque
+            tau_total[winch.idx] ~ tau_motor[winch.idx] +
+                                   drum_radius / gear_ratio * winch_force[winch.idx] -
+                                   tau_friction[winch.idx]
+            α_motor[winch.idx] ~ tau_total[winch.idx] / inertia_total
+            tether_acc[winch.idx] ~ drum_radius / gear_ratio * α_motor[winch.idx]
+
             winch_force_vec[:, winch.idx] ~ F
             winch_force[winch.idx] ~ norm(winch_force_vec[:, winch.idx])
         ]

src/model_management.jl

@@ -37,7 +37,8 @@ function generate_prob_getters(sys_struct, sys)
     if length(groups) > 0; get_group_state = getu(sys, c.([sys.twist_angle, sys.twist_ω, sys.group_tether_force, sys.group_tether_moment, sys.group_aero_moment])); end
     if length(pulleys) > 0; get_pulley_state = getu(sys, c.([sys.pulley_len, sys.pulley_vel])); end
     if length(winches) > 0
-        get_winch_state = getu(sys, c.([sys.tether_len, sys.tether_vel, sys.set_values, sys.winch_force_vec]))
+        get_winch_state = getu(sys, c.([sys.tether_len, sys.tether_vel, sys.set_values,
+                                       sys.winch_force_vec, sys.tau_friction]))
         set_set_values = setp(sys, sys.set_values)
         get_set_values = getp(sys, sys.set_values)
     end
@@ -509,8 +510,7 @@ function get_sys_struct_hash(sys_struct::SystemStructure)
         push!(data_parts, ("tether", tether.idx, tether.segment_idxs))
     end
     for winch in winches
-        model_type = winch.model isa TorqueControlledMachine
-        push!(data_parts, ("winch", winch.idx, model_type, winch.tether_idxs))
+        push!(data_parts, ("winch", winch.idx, winch.tether_idxs))
     end
     for wing in wings
         push!(data_parts, ("wing", wing.idx, wing.group_idxs))

src/predefined_structures.jl

@@ -156,9 +156,9 @@ function create_4_attach_ram_sys_struct(set::Settings)
                       STEERING_LINE, dynamics_type; z)
 
     winches = [
-        Winch(1, TorqueControlledMachine(set), [left_power_idx, right_power_idx])
-        Winch(2, TorqueControlledMachine(set), [left_steering_idx])
-        Winch(3, TorqueControlledMachine(set), [right_steering_idx])
+        Winch(1, set, [left_power_idx, right_power_idx])
+        Winch(2, set, [left_steering_idx])
+        Winch(3, set, [right_steering_idx])
     ]
 
     vsm_aero = BodyAerodynamics([vsm_wing])
@@ -299,9 +299,9 @@ function create_ram_sys_struct(set::Settings)
                       STEERING_LINE, dynamics_type; z)
 
     winches = [
-        Winch(1, TorqueControlledMachine(set), [left_power_idx, right_power_idx])
-        Winch(2, TorqueControlledMachine(set), [left_steering_idx])
-        Winch(3, TorqueControlledMachine(set), [right_steering_idx])
+        Winch(1, set, [left_power_idx, right_power_idx])
+        Winch(2, set, [left_steering_idx])
+        Winch(3, set, [right_steering_idx])
     ]
 
     vsm_aero = BodyAerodynamics([vsm_wing])
@@ -361,9 +361,9 @@ function create_tether_sys_struct(set::Settings;
                       axial_stiffness=axial_stiffness[4], axial_damping=axial_damping[4])
 
     winches = [
-        Winch(1, TorqueControlledMachine(set), [left_power_idx, right_power_idx]; brake=true)
-        Winch(2, TorqueControlledMachine(set), [left_steering_idx]; brake=true)
-        Winch(3, TorqueControlledMachine(set), [right_steering_idx]; brake=true)
+        Winch(1, set, [left_power_idx, right_power_idx]; brake=true)
+        Winch(2, set, [left_steering_idx]; brake=true)
+        Winch(3, set, [right_steering_idx]; brake=true)
     ]
 
     transforms = [Transform(1, deg2rad(set.elevation), deg2rad(set.azimuth), deg2rad(set.heading);
@@ -433,9 +433,9 @@ function create_simple_ram_sys_struct(set::Settings;
         Tether(4, [4], 8)
     ]
     winches = [
-        Winch(1, TorqueControlledMachine(set), [1,2])
-        Winch(2, TorqueControlledMachine(set), [3])
-        Winch(3, TorqueControlledMachine(set), [4])
+        Winch(1, set, [1,2])
+        Winch(2, set, [3])
+        Winch(3, set, [4])
     ]
     vsm_aero = BodyAerodynamics([vsm_wing])
     vsm_solver = Solver(vsm_aero; solver_type=NONLIN, atol=2e-8, rtol=2e-8)

src/simulate.jl

@@ -32,7 +32,8 @@ function sim!(
     total_time=10.0,
     vsm_interval=3,
     prn=true,
-    lin_model::Union{Nothing, <:NamedTuple, StateSpace}=nothing
+    lin_model::Union{Nothing, <:NamedTuple, StateSpace}=nothing,
+    torque_damp=0.9,
 )
     steps = Int(round(total_time / dt))
     sys_struct = sam.sys_struct
@@ -55,12 +56,14 @@ function sim!(
     set_torques = similar(set_values)
     y_op = sam.simple_lin_model.get_y(sam.integrator)
 
+    steady_torque = calc_steady_torque(sam)
+
     # --- Nonlinear Simulation Loop ---
     elapsed = @elapsed for step in 1:steps
         t = (step-1) * dt
 
-        set_torques[step, :] = -sam.set.drum_radius .* [norm(winch.force) for winch in sys_struct.winches]
-        set_torques[step, :] .+= set_values[step, :]
+        steady_torque = torque_damp * steady_torque + (1-torque_damp) * calc_steady_torque(sam)
+        set_torques[step, :] = steady_torque .+ set_values[step, :]
 
         try
             step_time += @elapsed next_step!(sam;

src/symbolic_awe_model.jl

@@ -481,12 +481,13 @@ function update_sys_struct!(prob::ProbWithAttributes,
         end
     end
     if length(winches) > 0
-        tether_len, tether_vel, set_value, winch_force_vec = prob.get_winch_state(integ)
+        tether_len, tether_vel, set_value, winch_force_vec, friction = prob.get_winch_state(integ)
         for winch in winches
             winch.tether_len = tether_len[winch.idx]
             winch.tether_vel = tether_vel[winch.idx]
             winch.set_value = set_value[winch.idx]
             winch.force .= winch_force_vec[:, winch.idx]
+            winch.friction = friction[winch.idx]
         end
     end
     if length(tethers) > 0
@@ -545,6 +546,18 @@ function get_model_name(set::Settings; precompile=false)
     return "model_$(ver)_$(set.physical_model)_$(dynamics_type)_$(set.segments)_seg.bin$suffix"
 end
 
+"""
+    calc_steady_torque(sam::SymbolicAWEModel)
+
+Calculates the torque for each winch that results in zero acceleration (steady state).
+"""
+function calc_steady_torque(sam::SymbolicAWEModel)
+    sys_struct = sam.sys_struct
+    torques = -[winch.drum_radius / winch.gear_ratio * norm(winch.force) +
+                winch.friction for winch in sys_struct.winches]
+    return torques
+end
+
 """
     calc_aoa(s::SymbolicAWEModel)