Simulating Railroads with OpenUSD

Simulating Railroads with OpenUSD: A New Era in Railway System Optimization

Summary: Railroad simulation using OpenUSD and NVIDIA Omniverse is revolutionizing the way engineers and developers optimize railway systems. This technology provides realistic simulations of physical interactions, forces, and dynamics between components, enabling comprehensive scenario analysis, predictive maintenance, and the exploration of innovative solutions. In this article, we’ll delve into the details of simulating railroads with OpenUSD, exploring its benefits, features, and applications.

The Importance of Railroad Simulation

Railroad simulation is crucial in modern transportation and logistics. It serves as a virtual testing ground for the intricate interplay of tracks, switches, and rolling stock, allowing engineers and developers to fine-tune and optimize railway systems. This ensures efficiency, safety, and cost-effectiveness, contributing to the advancement and sustainability of rail infrastructure.

Realistic Rail Simulations with railOmniverse Extension

The railOmniverse extension, developed in NVIDIA Omniverse by Trend Verlag with Deutsche Bahn, facilitates the simulation of highly complex railroad systems. Based on the Trend Trax Track Library, this extension provides tools for creating and managing track systems, motor models, brakes, and wheel friction in a physical railroad simulation. railOmniverse uses NVIDIA PhysX to support the realistic simulation of physical interactions, forces, and dynamics between the various components of a railroad system.

Key Features of railOmniverse

• Track System Creation Tools: Tools for defining the geometry of the tracks, specifying curves and twists, and managing switches and transitions between different track segments.
• Motor Model: Simulates the behavior of train motors, establishing a relationship between velocity and the fraction of maximal motor force that can be applied at a specific velocity.
• Friction and Brakes: Models for wheel-related friction and brakes, enabling the simulation of the effects of friction on the train’s movement and the application of braking forces to slow down or stop the train.
• Bogies and RailRunners: Interfaces for representing bogies and connecting multiple bogies together to form a train, including models for hinged bogies and rolling stock configurations.
• Sensors and Signals: Mechanisms for detecting events along the track, such as the passage of wheelsets or other specific events, and conveying information to be sent to a train as it moves along a track range.

Fine-Tuning Physical Simulations with TrackJoint and NVIDIA PhysX

The introduction of the TrackJoint feature provides a robust solution for simulating the physical interactions between the wheel frames of a train and the track system. TrackJoint restricts the movements of the wheel frames relative to the track while maintaining stability and realism in the simulation. This feature integrates seamlessly with NVIDIA PhysX, enabling the simulation of complex scenarios such as turntables or trains running on other rolling stock.

Integration into NVIDIA PhysX

The implementation of the TrackJoint mirrors the approach used for built-in joints, such as rotational or spherical joints. This involves defining a series of constraints for relative translational and rotational velocities, which are then provided to the PhysX constraint solver for direct use.

Collaboration and Custom Schemas with OpenUSD

The OpenUSD interchange proved to be an effective medium for collaboration between Deutsche Bahn and Trend. Custom USD primitive definitions were agreed upon for tracks and switches, enabling the creation of realistic simulations from sample data using the functionality of the Trax Library.

Leveraging the Schema Mechanism

The Trend development team defined and registered new primitives for tracks, switches, the TrackJoint, and various aspects of the motor model. This facilitated simultaneous development on both ends, with Deutsche Bahn providing track geometry data using Omniverse Bezier BasisCurves and Trend expanding the system with specialized spline curves.

Exploring the Trax Library

Libraries such as the Trend Trax Track Library are crucial for saving time and effort when creating realistic simulations. The Trax Library includes numerous features that have been tested in real-world use cases and are ready to use in railway simulations.

Key Benefits of the Trax Library

• Pre-Solved Fundamental Problems: The library pre-solves fundamental problems, allowing users to start their simulation projects with a solid foundation.
• Real-World Use Cases: Features such as the TrackJoint have been tested in real-world use cases, ensuring their reliability and effectiveness.
• Comprehensive Features: The library includes tools for defining track geometry, simulating motor behavior, modeling friction and brakes, and representing bogies and rail runners.

Future Directions

As the technology continues to evolve, we can expect to see even more advanced simulations and applications. The public release of railOmniverse in early 2024 will further democratize access to this powerful tool, enabling a broader range of users to benefit from its capabilities. With OpenUSD and NVIDIA Omniverse at the forefront, the future of railroad simulation looks bright.

Table: Key Features of railOmniverse

Table: Benefits of the Trax Library

Conclusion

Simulating railroads with OpenUSD and NVIDIA Omniverse is a game-changer for the railway industry. It provides a powerful tool for engineers and developers to optimize railway systems, ensuring efficiency, safety, and cost-effectiveness. With its realistic simulations, comprehensive features, and collaborative capabilities, this technology is poised to revolutionize the way railways are designed, operated, and maintained.