Counter Monitor - Quick Reference
Use this tool to detect dropped IMU packets and validate communication quality.
# Quick 60-second check
ros2 run oscp_imu_ros2 counter_tracker --ros-args -p duration:=60.0
# Expected output (good):
# /oscp/raw: 100.0 Hz (6000 msgs)
# Total missed packets: 0
Common Commands
Validate Before Deployment (5 minutes)
ros2 run oscp_imu_ros2 counter_tracker --ros-args -p duration:=300.0
Monitor Continuously (until Ctrl+C)
ros2 run oscp_imu_ros2 counter_tracker
Interpreting Output
Console (Good)
/oscp/raw: 100.0 Hz (100 msgs)
/oscp/imu/data: 100.0 Hz (100 msgs)
... (no warnings)
Total missed packets: 0
Console (Warning)
[WARN] Gap detected at 1234567 ms: last=42 expected=43 received=47 missed=4 (total=12)
CSV File
timestamp_ms,last_counter,expected_counter,received_counter,missed
1234567,42,43,47,4
1234800,99,100,105,5
Expected Hz Values
| Topic |
LOW Mode |
MEDIUM Mode |
Status |
/oscp/raw |
100 Hz |
500 Hz |
Always enabled |
/oscp/quat |
100 Hz |
100 Hz |
If enabled |
/oscp/euler |
100 Hz |
100 Hz |
If enabled |
/oscp/rot |
100 Hz |
100 Hz |
If enabled |
/oscp/gnss |
1 Hz |
1 Hz |
If enabled |
/oscp/imu/data |
100 Hz |
100 Hz |
If publish_standard_ros=true |
/oscp/imu/mag |
100 Hz |
100 Hz |
If publish_standard_ros=true |
/oscp/imu/temp |
100 Hz |
100 Hz |
If publish_standard_ros=true |
0 Hz = Normal (topic not enabled)
1 Hz = Normal (GNSS Frame)
100 Hz = Normal (LOW or MEDIUM AHRS)
500 Hz = Normal (MEDIUM raw only)
Troubleshooting
| Symptom |
Cause |
Fix |
| All topics at 0 Hz |
IMU node not running |
ros2 launch oscp_imu_ros2 oscp_imu.launch.py |
| Topic suddenly stops updating |
Hardware disconnected |
Check USB/CAN cable |
Files Generated
| File |
Contents |
counter_gaps.csv |
One row per dropped packet |
When to Use
- Before field deployment – Validate IMU works cleanly
- During sensor fusion tuning – Correlate gaps with EKF divergence
- When debugging nav stack – Rule out IMU communication issues
- After hardware changes – Verify new cables/adapters