NightSim: Real-Time Scheduling for Simulation and Control Applications

In real-time systems, timing isn’t just important—it defines whether the system works at all. For simulation, hardware-in-the-loop (HiL), or embedded control loops, the ability to run processes cyclically, with deterministic precision, is fundamental.

NightSim is designed to meet those demands. It provides a graphical interface for scheduling and managing real-time Linux processes in synchronized cycles. Whether you’re coordinating a multi-process simulation model or controlling time-sensitive hardware, NightSim helps ensure everything runs at the right time, in the right order, and within the right constraints.

Built for Predictability

Many simulation and control systems operate in cycles. Each cycle might involve sensor inputs, control calculations, and actuator outputs—all of which need to occur on a strict timeline. If one step overruns its slot, the entire system can fall out of sync.

NightSim lets developers define major and minor cycles, assign processes to each, and monitor their behavior in real time. It integrates with the Frequency-Based Scheduler (FBS) provided by RedHawk Linux, allowing for high-resolution cyclic execution.

You can specify cycle durations, execution order, and trigger sources such as real-time clocks or external interrupts. NightSim ensures that your timing rules are enforced, and that overruns are flagged or halted before they cascade.

Graphical Scheduling Control

The NightSim interface is designed for clarity. Developers can build and modify process groups visually, assigning each task a position in the scheduling cycle.

This interface allows you to:

• Group related processes and control them as a unit
• Define when and how often each process runs
• Visualize actual execution time versus expected time
• Detect and respond to timing errors immediately

Instead of editing configuration files or writing scripts, engineers can construct and test scheduling scenarios interactively.

Real-Time Performance Monitoring

Beyond scheduling, NightSim tracks performance data for every process under its control. You can monitor:

• Execution duration
• Minimum and maximum cycle times
• CPU load across processors
• Frame overruns and underruns

This visibility allows you to optimize system utilization without violating timing guarantees. If one process begins to take longer than expected, or if the system becomes overloaded, NightSim makes those issues visible early.

For simulation developers, this can help balance loads across multiple cores or adjust cycle durations to match physical hardware constraints.

Reusable Configurations and Script Support

NightSim configurations can be saved and reused. Once a scheduling model is working correctly, it can be exported as a script and applied to other systems.

• Aerospace and automotive HiL testing
• Robotics simulations with real sensor feedback
• Real-time control systems for power grids or industrial machinery

In these contexts, each part of the simulation must respond predictably to both virtual and physical inputs. NightSim keeps everything aligned, even when multiple processes are involved, running across multiple cores, and being triggered by real-time events.

Integration with RedHawk Linux

NightSim works in concert with RedHawk Linux, a real-time operating system known for its deterministic behavior and low interrupt latency. This pairing ensures that the scheduling behavior you configure in NightSim is enforced by an OS that’s built to prioritize timing guarantees.

Because NightSim uses the same system-level hooks as RedHawk’s scheduler, it offers tight control over process behavior with minimal overhead.

Conclusion

Real-time simulation and control systems can’t afford to improvise. They need structure, timing discipline, and transparency. NightSim provides all three.

With intuitive configuration, precise execution tracking, and robust integration with RedHawk Linux, NightSim makes it possible to build and manage process schedules that hold up under pressure. Whether you’re modeling a flight controller or managing a multi-loop robotic system, NightSim ensures your processes run on time, every time.