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CDS

Geometric Constraint and Inverse Kinematics Solver for 2D and 3D Models

Constraint Design Solver (CDS) embeds the full spectrum of geometric constraint intelligence — from parametric sketches and free-form surfaces to constrained assemblies and robot inverse kinematics — in one production-proven, self-diagnosing component your application owns.

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Trusted by leaders in robotics, metrology, and manufacturing

What is CDS?

From Sketch Constraints to Robot Kinematics

CDS is Spatial's 2D and 3D geometric constraint manager and solver: describe your geometry and the rules between it, press solve, and get a valid, fully diagnosed result, from parametric sketches and free-form NURBS surfaces to constrained assemblies and analytical robot inverse kinematics.

Add SpaCD when motion needs collision checks, the Path Planning pilot when it needs an optimal, collision-free route — and you're ready to take a design from constrained sketch to a robot moving safely through its cell.

Built on Dassault Systèmes V5/V6 constraint technology and shipping as native C++ with an official .NET 6 binding and a WebAssembly build path, it drops into the stack you already have.

Your team builds the application; CDS handles the geometry math.

The core

2D and 3D
Constraint Management

Use cases

Sketching — the constrained 2D profiles that features and 3D shapes are built on.
Assembly modeling & dynamic simulation — define how an assembly is constrained, then explore how it moves.
Part alignment — align two or more CAD parts through constraints, e.g. a measured part to the CMM turntable at a specific face.

Functionnality Includes

Dimensional & logical constraints, joints, patterns, rigid sets, and equations & variables.
Three solver modes — Update, Move-Under-Constraints, and Simulation.
Helper points and chirality control to steer ambiguous solutions.
DOF analysis and auto-constraining that report how well-defined the model is.
A multithreaded solver core that keeps editing interactive.

Motion

Inverse Kinematics Solver

How it works

From an end effector's start and end positions, CDS computes how every link in the chain must move.
The transformation matrices describing that motion are returned to your application.
CDS solves kinematics only — gravity and contact forces are out of scope

Uses Cases

CMM — program how a probe or stylus travels across the surface being measured
Robotics — drive a full arm from nothing more than the end effector's targets

Building blocks

Twelve Geometry Types,
One Pattern

Supported geometry types

Points, lines, and planes.
Circles, ellipses, parabolas, and hyperbolas.
Cylinders, cones, spheres, and tori.
NURBS curves and surfaces.

One consistent API

Every type is created and removed through one consistent API pattern.
Learn one geometry and you've learned all twelve — integrations come together faster.

Relationships

Constraints and Joints
for Every Relationship

Constraint types

Dimensional — distance, angle, radius, curvature, and segment length.
Logical — coincidence, tangency, parallelism, perpendicularity, concentricity, midpoint, and symmetry.
Every constraint follows the same create-and-remove pattern as the geometry.

Joint types

Planar, revolute, and prismatic joints for the fundamental motions.
Cylindrical, spherical, and universal joints for compound articulation.

Solving

Three Ways to Solve

The three modes

Update — automatically positions geometry to satisfy every constraint, with partial solve and chirality preservation as options.
Move-Under-Constraints — moves geometry iteratively and interactively toward the constraints.
Simulation — a flavor of MUC driven by the variables on dimensional constraints.

Solver behavior

One solver core runs all three modes.
When no exact solution exists, MUC and Simulation land the geometry as close to the target as possible instead of failing.

Built for Production

Why Choose Constraint Design Solver?

Comprehensive Functionality

A complete suite of geometry objects, dimensional and logical constraints, and joints — define and modify 2D profiles, position 3D assemblies, and drive the articulated motion between them.

High-Performance & Thread-Safe

A robust, fast, multithreaded solver handles under- and over-constrained systems alike, with three solver modes and flexible options to match every interaction. And when no exact solution exists, it lands as close to the target as possible instead of failing

Diagnose, Don't Guess

Per-constraint and per-entity status, DOF analysis, redundancy and conflict detection, plus replay and scripting — CDS tells you where and why a solve behaves the way it does, cutting integration and support cost.

Rapid, Easy Implementation

Consistent, object-oriented interfaces with real-time feedback and debugging, backed by a "getting started" application infrastructure — you're solving constraints on day one.

Enhanced Productivity

CDS shortens time to market by letting your team concentrate on its core product instead of the mathematical intricacies of geometric constraint solving.

Use cases

What Can You Build with CDS?

Design & Sketching

A sketcher your users can trust at speed — interactive move-under-constraints drag, help points for ambiguous solutions, chirality control so geometry never flips, and a live DOF read-out at every edit.

Modeling: Curves & Surfaces

Free-form quality that survives editing: constrained NURBS curves and surfaces with tangency, curvature, and length control keep continuity intact through every change.

Robotics & Automation

Eight joint types, analytical inverse kinematics, forward simulation, and singularity detection — motion, reachability, and collision-aware planning on one foundation.

Assembly & Mechanisms

Assemblies that reposition predictably, and explain themselves when they don't: a full mate set, rigid sets for subassemblies, patterns, and conflict localization that points to the exact mate at fault.

CAM & Toolpaths

Profile geometry your toolpaths can rely on — offset curves that auto-trim their self-intersections, segment-length control for clean passes, and SpaCD collision checks between tool and blank before metal moves.

Metrology & Inspection

Fitting you can certify: constrained fits over analytic and free-form geometry, probe-path kinematics within machine limits, and an honest read-out — well-, under-, or over-defined — on every result.

Simulation & Digital Twins

Well-posed models before the first run: parameters coupled by equations, motion supplied by joints and forward simulation, and DOF analysis confirming nothing is over- or under-constrained.

Configurators & Web

Rule-safe by construction: bounded variables and equations keep every configuration valid, instance reuse makes re-solves fast, and the WebAssembly build path points the same solver at the browser.

Kinematics

Drive Motion with Built-In Inverse Kinematics

CDS isn't only about where geometry sits — it's about how it moves.

Its analytical inverse kinematics solver takes the start and end positions of an end effector and computes how every link in the chain must move to get there, returning the transformation matrices that describe the motion. For robots of seven degrees of freedom and above it returns multiple solution branches, and forward simulation with singularity detection lets you validate the motion before it runs.

Robotics

from the start and end points of a robot's end effector, CDS programs how the remaining links move to satisfy the kinematic constraints.

Metrology (CMM)

program how a probe or stylus travels across the surface of the part being measured, respecting the machine's kinematic constraints.

Companion kernel

Keep Motion Collision-Free with SpaCD

Planning how a robot moves is only half the problem

You also need to know it won't hit anything. SpaCD is Spatial's optional collision-detection add-on for CDS: a fast, mesh-based kernel that verifies the motion you plan is clear of obstacles in real time.

What it is — a collision-detection kernel based on triangular meshes that reports whether bodies collide, and the details of where.
Use cases — detect collisions between a robot and its environment or work cell, and between a cutting tool and the blank.
How it works — build a hierarchy of meshes, geometries, and groups, apply transformations as the scene moves, and query for collisions at every step.

Pilot Program

Find the Optimal Collision-Free Path

The newest solver in the family

The newest solver in the family. Given a sequence of targets, Path Planning computes the collision-free, optimal route for a robot or machine assembly from point A to B to C — and returns the kinematics of every link along the way. It works from your space configuration, clash rules (clearance, contact, penetration), the mechanism's valid degrees of freedom, and your own constraints.

Use cases — programming for inspection, arc welding, assembly, pick & place, and tool transitions; collision-free motion in machine tools and industrial robots.
End-user benefits — verify manufacturing processes earlier to reduce cost, and optimize machine cycles for speed, energy consumption, and sequence ordering.
Diagnostics — when no path can be found, the solver reports why, so the scenario can be reset manually or programmatically.

Get Started With Spatial

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