Project Chrono: Brief Introduction

Brief Introduction

The following is a short list of main attributes of Chrono.

## Physics modeling

- Rigid body support.
- Flexible body support - both for ANCF and co-rotational nonlinear finite element analysis.
- Support for fluid-solid interaction problems, via Chrono::FSI module.
- Coulomb friction model capturing stick-slip phenomena.
- Support for rolling friction and spinning friction.
- Support for handling frictional contact via two approaches: a complementarity approach and a penalty approach.
- Springs and dampers with non-linear response. Can be user defined.
- Large collection of joints and constraints: spherical, revolute, prismatic, universal, glyph, screw, bevel and spur gears, pulleys, etc.
- Unilateral constraints.
- Constraints to impose trajectories, or to force motion on splines, curves, surfaces, etc.
- Constraints can have limits (ex. elbow).
- Constraints can be rheonomic or holonomic.
- Custom constraint for linear motors.
- Custom constraint for pneumatic cylinders.
- Custom constraint for motors, with reducers, learning mode, etc.
- On the fly constraint activation/deactivation.
- Simplified 1D dynamic models. Examples: powertrain, clutches, brakes, etc. For more sophisticated models see the Chrono::Vehicle module.
- All physical items can have an arbitrary number of 'assets' used for defining visualization shapes, custom properties, etc.

## Solver

- HHT solver for index 3 differential algebraic equations.
- Symplectic first order half-implicit Euler solver for large frictional contact problems.
- Speed-impulse level solver for handling large frictional contact problems.
- Handling of redundant/ill posed constraints.
- Stabilization or projection methods to avoid constraint drifting.
- Static analysis solver.
- Inverse kinematics and interactive manipulation.

## Collision detection features

- Supports compounds of spheres, cubes, convex geometries, triangle meshes, etc.
- Additional collision support provided by the Bullet collision detection engine, which is wrapped inside Chrono::Engine.
- Broad phase collision detection: sweep-and-prune SAT.
- Narrow phase collision detection: AABB and/or OBB binary volume trees.
- Detail phase with custom primitive-to-primitive fallbacks.
- Safety 'envelope' around objects.
- Report penetration depth, distance, etc.
- Bodies can be activated/deactivated, and can selectively enter collision detection.

## Implementation details

- Eigen-based matrix and vector operations.
- Optimized custom classes for vectors, quaternions, matrices.
- Optimized custom classes for coordinate systems and coordinate transformations.
- All operations on points/speeds/accelerations are based on quaternion algebra.
- Special archive engine, with easy and reliable persistent/transient serialization.
- Expandable run-time class factory.

## Other

- Template-based vehicle modeling through Chrono::Vehicle
- Scripting via Python (Chrono::Python)
- Import STEP cad files to define complex geometries
- Run-time visualization with Irrlicht or VSG
- Post-processing visualization with POV-Ray or Blender
- Build system based on CMake (cross-platform, on Windows 64 bit, Linux, MacOS).