Define rosbag recording arch for mixed-rate logging (LiDAR 20 Hz + VectorNav 100 Hz)

[Deep-Axe]

Summary

Target rates are:

• LiDAR: 20 Hz
• VectorNav: 100 Hz

Current status: as noted in Issue #1, both are running at 20 Hz right now.

Once VectorNav is restored to 100 Hz, we need to decide the correct recording architecture.
At present, both streams are logged into a single rosbag file.

Problem to solve

When LiDAR and VectorNav run at different frequencies (20 vs 100), we need to decide whether to:

1. Keep recording both into a single rosbag, or
2. Record into two separate rosbags in the same session folder, or
3. Support both modes via a runtime flag/option in driver_node.

Context

• Single-file logging is simpler for replay and session management.
• Split-file logging may improve post-processing flexibility, and per-sensor workflows.
• We currently do not have enough usage data to lock this decision.

Proposed direction

• Evaluate both approaches with representative workloads.
• Add a configurable run option (e.g. --bag-mode single|split) so behavior can be selected per use case.
• Keep current behavior as default unless testing shows a clear reason to switch.

Acceptance criteria

• Decision documented with pros/cons and rationale.
• Recording strategy implemented (single, split, or configurable mode).
• If configurable mode is chosen:
  • CLI option is added and documented.
  • Output folder structure is clearly defined.
• Verified recording works correctly with LiDAR at 20 Hz and VectorNav at 100 Hz.