OpenSourceAWE · 1-Bart-1 · Oct 25, 2025 · Oct 25, 2025 · Oct 28, 2025 · Oct 28, 2025
diff --git a/REUSE.toml b/REUSE.toml
@@ -18,7 +18,7 @@ SPDX-FileCopyrightText = "2025 Uwe Fechner, Bart van de Lint"
 SPDX-License-Identifier = "MIT"
 
 [[annotations]]
-path = ["docs/src/*.png", "docs/src/*.svg", "docs/src/*.md", "data/.gitignore"]
+path = ["docs/src/*.png", "docs/src/*.svg", "docs/src/*.md", "data/.gitignore", "docs/src/assets/group_slice.svg"]
 SPDX-FileCopyrightText = "2025 Uwe Fechner, Bart van de Lint"
 SPDX-License-Identifier = "CC-BY-4.0"
 

diff --git a/bin/reuse_lint b/bin/reuse_lint
@@ -0,0 +1,5 @@
+# Copyright (c) 2025 Uwe Fechner
+# SPDX-License-Identifier: MIT
+
+cd ..
+pipx run reuse lint
diff --git a/docs/Project.toml b/docs/Project.toml
@@ -1,3 +1,6 @@
 [deps]
 Documenter = "e30172f5-a6a5-5a46-863b-614d45cd2de4"
 KiteUtils = "90980105-b163-44e5-ba9f-8b1c83bb0533"
+
+[sources]
+KiteUtils = {path = ".."}
diff --git a/docs/make.jl b/docs/make.jl
@@ -29,6 +29,7 @@ makedocs(;
         "Reference frames" => "reference_frames.md",
         "Exported Functions" => "functions.md",
         "Exported Types" => "types.md",
+        "System Structure" => "system_structure.md",
         "Examples" => "examples.md",
     ],
 )

diff --git a/docs/src/assets/group_slice.svg b/docs/src/assets/group_slice.svg
diff --git a/docs/src/reference_frames.md b/docs/src/reference_frames.md
@@ -6,6 +6,30 @@ CurrentModule = KiteUtils
 ## Position and velocity
 For position and velocity vectors of the model the **ENU** (East North Up) reference frame is used.
 
+## World Frame and CAD Frame
+
+### World Frame
+The **world frame** is the general inertial reference frame used for all simulation dynamics in the system structure. By default, the **ENU** (East-North-Up) frame is used as the world frame in [`SystemStructure`](@ref), with the following properties:
+- **Origin**: Located at the winch position (0, 0, 0)
+- **x-axis**: Points East
+- **y-axis**: Points North
+- **z-axis**: Points Up (vertical, opposite to gravity)
+
+All dynamic quantities (positions, velocities, forces) are expressed in this world frame during simulation.
+
+### CAD Frame
+The **CAD frame** is the coordinate system in which the system geometry is initially defined (e.g., in CAD software). The CAD frame can have an arbitrary origin and orientation - it does not need to match the world frame.
+
+When constructing a [`SystemStructure`](@ref):
+- All points are initially specified with `pos_cad` positions in the CAD frame
+- [`Transform`](@ref) objects convert these CAD frame coordinates to world frame coordinates
+- The `base_pos` argument in a Transform specifies where the CAD frame origin should be placed in the world frame
+- After transformation, all simulation proceeds in the world frame
+
+This separation allows system geometry to be defined in whatever coordinate system is most convenient for design, then automatically converted to the simulation frame.
+
+## Wind and Controller Frames
+
 The controller is using the **W** (Wind) reference frame as shown in the figure below, y-axis downwind and z-axis up.
 
 The orientation of the kite is expressed with respect to the **EX** (Earth XSense = North East Down) reference frame.

diff --git a/docs/src/system_structure.md b/docs/src/system_structure.md
@@ -0,0 +1,100 @@
+```@meta
+CurrentModule = KiteUtils
+```
+
+## Introduction
+
+The [`SystemStructure`](@ref) provides a flexible framework for defining the physical
+structure of airborne wind energy (AWE) systems using discrete mass-spring-damper models.
+This structure can represent many different AWE system configurations, from simple
+single-line kites to complex multi-wing systems with intricate bridle networks.
+
+## Workflow
+
+1. Define system components ([`Point`](@ref), [`Segment`](@ref), [`Group`](@ref), [`BaseWing`](@ref), etc.)
+2. Assemble into a [`SystemStructure`](@ref)
+3. Initialize component positions using [`Transform`](@ref)s
+4. Simulate using [`SymbolicAWEModels.jl`](https://github.com/OpenSourceAWE/SymbolicAWEModels.jl)
+
+## Core Types and Constants
+
+### Simulation Types
+
+```@docs
+SimFloat
+KVec3
+KVec4
+SVec3
+```
+
+### Public Enumerations
+
+```@docs
+SegmentType
+DynamicsType
+```
+
+## System Components
+
+### Points and Point Dynamics
+
+```@docs
+Point
+Point(idx, pos_cad, type; wing_idx, vel_w, transform_idx, mass, bridle_damping, fix_sphere)
+```
+
+### Wing Deformation Groups
+
+```@docs
+Group
+Group(idx, point_idxs, le_pos, chord, y_airf, type, moment_frac)
+```
+
+### Segments and Connections
+
+```@docs
+Segment
+Segment(idx, set, point_idxs, type; l0, compression_frac, axial_stiffness, axial_damping)
+Segment(idx, point_idxs, axial_stiffness, axial_damping, diameter; l0, compression_frac)
+```
+
+### Pulleys and Length Redistribution
+
+```@docs
+Pulley
+Pulley(idx, segment_idxs, type)
+```
+
+### Tethers and Winch Control
+
+```@docs
+Tether
+Tether(idx, segment_idxs, winch_idx)
+Winch
+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 Components
+
+### Wing Abstractions and Implementations
+
+```@docs
+AbstractWing
+BaseWing
+```
+
+### Spatial Transformations
+
+```@docs
+Transform
+Transform(idx, elevation, azimuth, heading; base_point_idx, base_pos, base_transform_idx, wing_idx, rot_point_idx)
+Transform(idx, set; wing_idx, rot_point_idx, base_point_idx, base_pos, base_transform_idx)
+```
+
+## Complete System Structure
+
+```@docs
+SystemStructure
+SystemStructure(name, set; points, groups, segments, pulleys, tethers, winches, wings, transforms)
+```
diff --git a/examples/bridle_info.jl b/examples/bridle_info.jl
@@ -1,7 +1,8 @@
 # SPDX-FileCopyrightText: 2022 Uwe Fechner
 # SPDX-License-Identifier: MIT
 
-using KiteUtils, LinearAlgebra
+using KiteUtils
+using LinearAlgebra
 
 if basename(pwd()) == "examples" 
     set_data_path("../data")

diff --git a/scripts/build_docu.jl b/scripts/build_docu.jl
@@ -6,22 +6,25 @@
 
 using Pkg
 
-function globaldependencies()
-    projectpath = Pkg.project().path
-    basepath, _ = splitdir(projectpath)
-    Pkg.activate()
-    globaldependencies = keys(Pkg.project().dependencies)
-    Pkg.activate(basepath)
-    globaldependencies
-end
+# Check if LiveServer is installed globally
+current_project = Pkg.project().path
+Pkg.activate()
+has_liveserver = "LiveServer" in keys(Pkg.project().dependencies)
+Pkg.activate(current_project)
 
-if !("LiveServer" in globaldependencies())
+if !has_liveserver
     println("Installing LiveServer globally!")
     run(`julia -e 'using Pkg; Pkg.add("LiveServer")'`)
 end
 
-# if !("Documenter" ∈ keys(Pkg.project().dependencies))
-#     using TestEnv
-#     TestEnv.activate()
-# end
+# Activate the docs environment
+basepath = dirname(current_project)
+docs_path = joinpath(basepath, "docs")
+Pkg.activate(docs_path)
+
+# Instantiate to ensure all dependencies are installed
+if !isfile(joinpath(docs_path, "Manifest.toml"))
+    Pkg.instantiate()
+end
+
 using LiveServer; servedocs(launch_browser=true)
diff --git a/src/KiteUtils.jl b/src/KiteUtils.jl
@@ -42,10 +42,16 @@ SOFTWARE. =#
 # the parameter P is the number of points of the tether, equal to segments+1
 # in addition helper functions for working with rotations
 
-using PrecompileTools: @setup_workload, @compile_workload 
+using PrecompileTools: @setup_workload, @compile_workload
 using Rotations, StaticArrays, StructArrays, RecursiveArrayTools, Arrow, YAML, LinearAlgebra, DocStringExtensions
 using Parameters, StructTypes, CSV, Parsers, Pkg
 export Settings, SysState, SysLog, Logger, MyFloat
+export SimFloat, KVec3, KVec4, SVec3
+export SegmentType, POWER_LINE, STEERING_LINE, BRIDLE
+export DynamicsType, DYNAMIC, QUASI_STATIC, WING, STATIC
+export Point, Group, Segment, Pulley, Tether, Winch
+export AbstractWing, BaseWing
+export Transform, SystemStructure
 
 import Base.length
 import ReferenceFrameRotations as RFR
@@ -88,6 +94,7 @@ include("settings.jl")
 include("yaml_utils.jl")
 include("transformations.jl")
 include("trafo.jl")
+include("system_structure.jl")
 
 include("_sysstate.jl")
 
@@ -200,7 +207,7 @@ the apparent wind speed.
 
 Parameters:
 - `vec_c`: (`pos_n`-2) - (`pos_n`-1) n: number of particles without the three kite particles
-                                    that do not belong to the main thether (P1, P2 and P3).
+                                    that do not belong to the main tether (P1, P2 and P3).
 - `v_app`: vector of the apparent wind speed
 
 Returns:
@@ -217,7 +224,7 @@ end
     get_particles(height_k, height_b, width, m_k, pos_pod= [ 75., 0., 129.90381057], vec_c=[-15., 0., -25.98076211], 
                   v_app=[10.4855, 0, -3.08324])
 
-Calculate the initial positions of the particels representing 
+Calculate the initial positions of the particles representing 
 a 4-point kite, connected to a kite control unit (KCU). 
 
 Parameters:
@@ -238,7 +245,7 @@ function get_particles(height_k, height_b, width, m_k, pos_pod= [ 75., 0., 129.9
     h_kz = height_k * sin(beta); # print 'h_kz: ', h_kz
     h_bx = height_b * cos(beta)
     h_bz = height_b * sin(beta)
-    pos_kite = pos_pod - (h_kz + h_bz) * z + (h_kx + h_bx) * x   # top,        poing B in diagram
+    pos_kite = pos_pod - (h_kz + h_bz) * z + (h_kx + h_bx) * x   # top,        point B in diagram
     pos_C = pos_kite + h_kz * z + 0.5 * width * y + h_kx * x     # side point, point C in diagram
     pos_A = pos_kite + h_kz * z + (h_kx + width * m_k) * x       # nose,       point A in diagram
     pos_D = pos_kite + h_kz * z - 0.5 * width * y + h_kx * x     # side point, point D in diagram
@@ -337,7 +344,7 @@ end
 """
     save_log(flight_log::SysLog, compress=true; path="")
 
-Save a fligh log of type SysLog as .arrow file. By default lz4 compression is used, 
+Save a flight log of type SysLog as .arrow file. By default lz4 compression is used, 
 if you use **false** as second parameter no compression is used.
 """
 function save_log(flight_log::SysLog, compress=true; path="")
@@ -355,7 +362,7 @@ end
 """
     export_log(flight_log; path="")
 
-Save a fligh log of type SysLog as .csv file.
+Save a flight log of type SysLog as .csv file.
 """
 function export_log(flight_log; path="")
     if path == ""