Rhinoceros

LEDAS Ltd today announced the release of version 4.0 of LGS 3D, its powerful geometric constraint solver. This is the core technology for parametric design software, allowing users to express their design intent in 3D parts and assemblies through geometric and dimensional constraints.

Version 4.0 introduces important new functions that customers will find useful for assembly design and direct modeling. It also significantly improves reliability and performance.

LGS 3D v4 introduces (infinite) cone and torus objects. They can be fixed, or be linked with other objects with different constraints: coincidence, tangency, parallelism, perpendicularity, and angular dimensions. In the context of assembly designs, cone and torus objects are used to model spatial and kinematic relationships in mechanisms, such as bearings and variators. In direct modeling applications, they can represent fillets and chamfers, and they adjust their form to satisfy constraints. For example, cones can change their angles and tori change any of their radii. In addition to non-rigid cylindrical and spherical surfaces introduced in previous versions of LGS 3D, cone and tori now allow users to models many kinds of parametrized mechanical parts, such as brackets, bearings, and hinges.

An important function introduced with LGS 3D v4 computes the degrees of freedom (DOF) of parts in mechanisms. Any rigid set in LGS 3D can have up to three translational and three rotational DOFs. When rigid sets are linked by constraints to other fixed objects, the appropriate DOFs are eliminated automatically. A new function returns the number of remaining DOFs for a particular rigid set. Also returned is geometric information, such as directions and axes. LGS-based applications can now represent this data to the end user, a feature that has been highly requested for kinematic analysis.

LGS 3D v4 supports tangency constraints with parametric curves and surfaces that represent non-canonic objects. These features are used to express complex kinematic relations in advanced mechanisms.

Also new in LGS 3D is its ability to deform canonic curves and surfaces when they are moved under constraints. This applies specifically to circles, cylinders, spheres, cones and tori. (In previous versions, the deformation was limited to static constraint solving.) Version 4 also generates the correct diagnostics for models with these non-rigid objects.

A new LGS 3D function returns information about loops in over-defined constraints. (In previous versions, users were only alerted to the condition and were provided no additional information.) Version 4 now allows constraint relaxation to be applied independently of each over-defined loop. This means that it is now faster for users to make their models consistent.

Version 4.0 of LGS 3D contains significant advances in reliability and performance. A new analysis on inconsistent models improves performance three-fold. The technical and algorithmic optimization on large models with thousands constraints increases the performance of LGS 3D by 10-25%.

LGS 3D v4 also contains enhancements to its API that provide better context management and more detailed journaling.

“Version 4.0 really is a ‘major’ release,” explained Alexey Ershov, Director of Research and Development at LEDAS. “We are not only introducing important extensions, but for the first time are providing full solutions to both assembly and part modeling.”

Since the first commercial release in 2004, LGS 2D and 3D software components have been licensed by a dozen CAD/CAM/CAE vendors, who have embedded the components into their applications successfully.

The 2D and 3D geometric constraint solvers are used as parametric engines for 2D sketching and drawing, 3D direct modeling, assembly design, motion analysis, and other applications. LGS 2D and 3D are cross-platform software packages running on 32- and 64-bit versions of Windows, Linux, Mac OS X, *BSD, AIX, HP-UX, and other operating systems. Both solvers have a C-style API for easy integration into a broad range of software applications using a variety of wrappers, such as .NET, Java, and C++.

LGS 2D/3D supports the creation and modification of geometric models through explicit and implicit constraints. Geometric objects that can be constrained include points, lines, circles, ellipses, planes, cylinders, spheres, cones, tori, NURBS, application-defined parametric curves, and surfaces. Objects can be fixed in the absolute coordinate system or relative to each other. Supported constraints include geometric relations between objects (coincidence, parallelism, tangency, and so on) and dimensions that specify the required values for distances, angles, and radii. LGS 2D/3D moves and rotates objects to positions that satisfy all constraints, yet minimizes transformations from initial configurations.

Other LGS functions implement advanced features of CAD/CAM/CAE systems, such as diagnostics of over- and under-defined parts of models, engineering variables and equations, help points, and tolerance management.

Available as free downloads from the LEDAS web site are “Lege’n’d 2D/3D” example applications. These consist of sample models representing different kinds of 2D sketches and 3D assemblies. The applications can be used to test the functionality, robustness, and performance of LGS 2D/3D. They were created with the Open CASCADE open-source application framework; the source code is available to all licensees.

To learn more about LGS 2D/3D, visit the LEDAS Web site at www.ledas.com/products/lgs3d.