velodyne_monitor#
Purpose#
This node monitors the status of Velodyne LiDARs. The result of the status is published as diagnostics. Take care not to use this diagnostics to decide the lidar error. Please read Assumptions / Known limits for the detail reason.
Inner-workings / Algorithms#
The status of Velodyne LiDAR can be retrieved from http://[ip_address]/cgi/{info, settings, status, diag}.json.
The types of abnormal status and corresponding diagnostics status are following.
| Abnormal status | Diagnostic status |
|---|---|
| No abnormality | OK |
| Top board temperature is too cold | ERROR |
| Top board temperature is cold | WARN |
| Top board temperature is too hot | ERROR |
| Top board temperature is hot | WARN |
| Bottom board temperature is too cold | ERROR |
| Bottom board temperature is cold | WARN |
| Bottom board temperature is too hot | ERROR |
| Bottom board temperature is hot | WARN |
| Rpm(Rotations per minute) of the motor is too low | ERROR |
| Rpm(Rotations per minute) of the motor is low | WARN |
| Connection error (cannot get Velodyne LiDAR status) | ERROR |
Inputs / Outputs#
Input#
None
Output#
| Name | Type | Description |
|---|---|---|
/diagnostics |
diagnostic_msgs/DiagnosticArray |
Diagnostics outputs |
Parameters#
Node Parameters#
| Name | Type | Default Value | Description |
|---|---|---|---|
timeout |
double | 0.5 | Timeout for HTTP request to get Velodyne LiDAR status [s] |
Core Parameters#
| Name | Type | Default Value | Description |
|---|---|---|---|
ip_address |
string | "192.168.1.201" | IP address of target Velodyne LiDAR |
temp_cold_warn |
double | -5.0 | If the temperature of Velodyne LiDAR is lower than this value, the diagnostics status becomes WARN [°C] |
temp_cold_error |
double | -10.0 | If the temperature of Velodyne LiDAR is lower than this value, the diagnostics status becomes ERROR [°C] |
temp_hot_warn |
double | 75.0 | If the temperature of Velodyne LiDAR is higher than this value, the diagnostics status becomes WARN [°C] |
temp_hot_error |
double | 80.0 | If the temperature of Velodyne LiDAR is higher than this value, the diagnostics status becomes ERROR [°C] |
rpm_ratio_warn |
double | 0.80 | If the rpm rate of the motor (= current rpm / default rpm) is lower than this value, the diagnostics status becomes WARN |
rpm_ratio_error |
double | 0.70 | If the rpm rate of the motor (= current rpm / default rpm) is lower than this value, the diagnostics status becomes ERROR |
Config files#
Config files for several velodyne models are prepared.
The temp_*** parameters are set with reference to the operational temperature from each datasheet.
Moreover, the temp_hot_*** of each model are set highly as 20 from operational temperature.
Now, VLP-16.param.yaml is used as default argument because it is lowest spec.
| Model Name | Config name | Operational Temperature [℃] |
|---|---|---|
| VLP-16 | VLP-16.param.yaml | -10 to 60 |
| VLP-32C | VLP-32C.param.yaml | -20 to 60 |
| VLS-128 | VLS-128.param.yaml | -20 to 60 |
| Velarray M1600 | Velarray_M1600.param.yaml | -40 to 85 |
| HDL-32E | HDL-32E.param.yaml | -10 to 60 |
Assumptions / Known limits#
This node uses the http_client and request results by GET method. It takes a few seconds to get results, or generate a timeout exception if it does not succeed the GET request. This occurs frequently and the diagnostics aggregator output STALE. Therefore I recommend to stop using this results to decide the lidar error, and only monitor it to confirm lidar status.