Watch movement design and analysis. Model in any CAD tool, export STEP, and OHS rigs the assembly
into a working movement, then animates it, simulates how it keeps time, checks that it is strong
enough, checks that you can make it with your tools, and teaches you as you go.
See plan.md for the design and the roadmap, and docs/ for the
user guide.
Status: 1.0. A complete command-line and Python tool (ohs):
| You want to | Command |
|---|---|
| Import a CAD assembly and rig it | ohs import, ohs rig check, ohs rig set |
| Read and animate the going train | ohs kinematics, ohs explain, ohs animate |
| See how it keeps time | ohs torque, ohs timekeeping, ohs simulate, ohs timegrapher, ohs whatif |
| Calibrate against your timegrapher | ohs bench compare, ohs bench calibrate, ohs calibre init |
| Check strength | ohs fea (tooth bending, shock, modes), ohs materials, ohs thermal |
| Check you can make it | ohs tolerance, ohs dfm, ohs collisions |
| Make a part | ohs gear (STEP, DXF, SVG, PDF), ohs draw |
| Write it up | ohs report (HTML and PDF) |
| Learn by doing | ohs lesson list, ohs lesson show, ohs lesson check |
| Trust the solvers | ohs verify physics --full, ohs verify levels |
Not in 1.0: the full graphical interface (ohs-gui is a first, basic one: docs/desktop.md), VTK rendering (OHS's own solvers stand in for MFEM and VTK; MFEM is linked only as an independent
cross-check, ohs fea --mfem, Netgen is an optional out-of-process 3D mesher, --mesher netgen, and Chrono is an
optional adapter for the escapement, -DOHS_WITH_CHRONO=ON) and escapements other than the Swiss lever and the spring detent (reduced model). docs/limitations.md is the full list.
Everything below was run on Ubuntu 24.04 with GCC 13; each command is what produced the binaries.
# 1. Dependencies (apt provides OCCT 7.6; the plan targets 8.0)
sudo apt install cmake ninja-build g++ python3 \
libocct-data-exchange-dev libocct-modeling-algorithms-dev libocct-foundation-dev \
libocct-modeling-data-dev libocct-ocaf-dev libocct-visualization-dev libeigen3-dev libcli11-dev \
libspdlog-dev nlohmann-json3-dev libtomlplusplus-dev catch2 libtbb-dev libhdf5-dev
sudo apt install qt6-base-dev # for the desktop app
# 2. Command line tool: release build and the test suite
./build.sh --jobs 14 # -> build/release/src/ohs
# 3. Desktop app (Qt 6 Widgets): same script, GUI preset
./build.sh --gui --jobs 14 --no-test # -> build/gui/src/ohs-gui (and build/gui/src/ohs)
Run them with build/release/src/ohs --help and build/gui/src/ohs-gui (add a project:
build/gui/src/ohs-gui movement.hsproj; File, Open the demonstration movement needs no CAD file).
./build.sh --help lists the other builds (--debug, --asan, --tsan, --coverage). The GUI tests run
offscreen: ctest --preset gui after a --gui build.
Optional libraries are used when found at configure time, and ohs fea says so when a feature is missing:
libmfem-dev (--mfem, --solver mfem), libvtk9-dev (--vtu-compressed), libhdf5-dev (--hdf5),
ffmpeg at run time (video export) and pip install netgen-mesher (--mesher netgen). Chrono and a
serial MFEM can be built at pinned commits with cmake/superbuild. The Python package
(-DOHS_BUILD_PYTHON=ON, needs nanobind), packages (cpack), Windows (build.ps1) and macOS presets are
described in docs/install.md.
build/release/src/ohs dev gen-movement -o train.step
build/release/src/ohs import train.step -o train.hsproj --beat-rate 25200
build/release/src/ohs kinematics train.hsproj
build/release/src/ohs timekeeping train.hsproj
build/release/src/ohs lesson show hairspring
Exit codes: 0 ok, 1 a check failed, 2 usage or input error. Every command takes --json.
import ohs
p = ohs.Project.import_step("train.step", "train.hsproj", beat_rate=25200)
print(p.timekeeping()["power_reserve_h"])- Python API 1.0 (frozen):
docs/python.md - Plugin ABI 1.0 (DFM rule sets in any language):
docs/plugins.md,include/ohs/plugin.h,examples/plugins/ - CAD add-ins (Fusion 360, SolidWorks):
integrations/
ohs thirdparty om10 fetch --file <your downloaded .stp> installs it under your user data
directory and imports it. OM10 files are CC BY-SA 3.0 and are never committed here
(.gitignore blocks *.stp/*.step). The OM10 tutorial walks through a whole
modification study with the guided lessons.
- Automatic winding: rotor animation and simulation. OHS recognises the rotor (oscillating
weight) of an automatic movement, from its name or from its place in the movement, and gives
it the
rotorrole. It does not model the winding yet: the rotor is drawn but does not move. The plan is to:- animate the rotor turning about the movement's centre;
- simulate the winding chain (reverser or pawl wheels, reduction gearing, the barrel ratchet) from wrist motion to mainspring torque;
- report winding efficiency and how much wear is needed to keep the movement at full power reserve.
Apache-2.0. See LICENSE.md and CHANGELOG.md.