Motus.Geometry 2.0.0

Motus.NET

.NET 8 host-agnostic motion-planning core: models, FK/IK, collision, sampling/Cartesian planners, retiming, and export.

No UI, no vendor runtime, no live robot I/O. Algorithm catalog: docs/METHODS.md · citations: docs/REFERENCES.bib.

Bundled presets (UR family) and URDF / xacro loaders; analytic IK for Universal Robots, numerical IK for generic chains. Parallel Stewart (Family=stewart, leg lengths in meters) and legged gait preview (Family=legged, radians) are first-class siblings of serial tip chains.

Licensed under MIT.

Contents

• Packages
• Quick start
• Planners
• Algorithms and references
• Context: attach, groups, SRDF
• Units and export
• Build and test
• Releases
• Safety
• Attribution

Packages

dotnet add package Motus.Core
dotnet add package Motus.Geometry
dotnet add package Motus.OMPL.NET
dotnet add package Motus.Presets

Rhino / desktop: managed planning and C# mesh collision are the default — no Linux .so required. See docs/rhino-host.md. Stub/NuGet builds often expose only RrtConnect in the planner registry; extra OMPL IDs need a full native build. Check MotusCapabilities.Describe().

Quick start

var robot = PresetLoader.LoadRobotModelByName("UR10e");
var start = HomePoseResolver.HomeOrZeros(robot);
var goal = new JointState(/* radians */);

var scene = new CollisionScene(new[] {
    CollisionObject.Sphere("obstacle", Frame.Identity, 0.1)
});
var checker = CollisionCheckerFactory.Create(robot);
var opts = new PlanningOptions {
    CollisionScene = scene,
    CollisionChecker = checker
};

var result = SamplingPlanner.Create(checker, new SamplingPlannerOptions {
    PlannerId = SamplingPlannerId.RrtConnect,
    MaxIterations = 4000
}).Plan(new PlanningRequest(robot, start, goal, opts));

if (result.Success)
    File.WriteAllText("plan.json", TrajectoryExport.ToJson(result.Trajectory!));

URDF:

var robot = UrdfRobotLoader.Load("robot.urdf", new UrdfLoadOptions {
    BaseLink = "base_link",
    TipLink = "tool0"
});
var fk = KinematicsResolver.CreateFkSolver(robot.Preset, robot.Chain);

Planners

Prefer SamplingPlanner + CollisionCheckerFactory.Create (or GetOrCreate for session reuse) over the obsolete RrtConnectPlanner wrapper.

// Motion program
var planner = new IndustrialMotionPlanner(robot.Preset);
var result = planner.Plan(new MotionProgramRequest(robot, start, new MotionSegment[] {
    new PtpSegment(ptpGoal, blendRadiusMeters: 0.004),
    new LinSegment(linGoal, stepMeters: 0.005),
    new CircSegment(via, circGoal, arcSamples: 12)
}));

Pick/place programs support explicit gripper contact, obstacle-aware transfers, and attachment timelines that survive retiming and export. See docs/pick-place.md.

Algorithms and references

Canonical detail (API, units, failure codes): docs/METHODS.md. BibTeX: docs/REFERENCES.bib.

<details> <summary><strong>Method catalog</strong> — area, behavior, citations (click to expand)</summary>

</details>

Context: attach, groups, SRDF

var ctx = PlanningContext.Create(robot, scene)
    .Attach("workpiece", workpieceBox, tcpLocalFrame)
    .ForGroup(SrdfLoader.LoadGroups("robot.srdf")[0]);

var checker = CollisionCheckerFactory.Create(robot, attached: ctx.Attached);
var result = SamplingPlanner.Create(checker).Plan(
    new PlanningRequest(robot, start, goal, ctx.ToPlanningOptions()));

Non-group joints stay locked at the start configuration.

Units & export

Internal units: radians, seconds, meters (Motus.Core.Units for °↔rad). Stewart configurations are meters (leg stroke); legged joints are radians.

TrajectoryExport.ToJson emits the PlanBundle contract for Grasshopper and control adapters:

• contractVersion / exportVersion — schema compatibility
• units, frameConvention — semantics
• diagnostics — machine-readable planner messages
• provenance — optional plannerId, seed, settings hash

Additive optional fields are safe; removing/renaming fields requires a major contractVersion bump.

Build & test

Requires .NET 9+ SDK to open the .slnx; libraries target net8.0.

dotnet build Motus.NET.slnx
dotnet test Motus.NET.slnx

Optional native library:

cmake -S native -B native/build -DMOTUS_USE_OMPL=ON -DMOTUS_USE_FCL=ON
cmake --build native/build
# Linux: export LD_LIBRARY_PATH=native/build

Benchmarks: benchmarks/Motus.Benchmarks (BenchmarkDotNet).

Releases

Tag vX.Y.Z → release workflow builds, tests, packs, publishes to nuget.org, and creates a GitHub Release.

Changelog: CHANGELOG.md. Package/Directory.Build.props targets 2.0.0 (NuGet publish on v2.0.0 tag). Latest published NuGet is 1.8.0 (GitHub v1.8.0). Use sibling project references until 2.0.0 is tagged and published.

Safety

Motus does not command physical robots. Presets and URDF imports are planning defaults — verify limits and calibration before hardware use. See docs/safety.md.

This library and bundled presets were developed with AI assistance; values are approximate and must be checked against manufacturer data.

Attribution

• Managed RRT-Connect implements Kuffner & LaValle (ICRA 2000). Native path uses OMPL (BSD-3-Clause) when built.
• Robot presets are approximate public-datasheet values for planning/visualization only.