Cannot get values of Laser range finder

[michele-colombo]

Tell us about your environment Jetson Xavier NX, DJI M300 with H20 payload. ROS2 humble in docker.

• Ubuntu version: 22.04 (host is 20.04)
• Docker Version:
• ROS/ROS2 version: Humble (with CycloneDDS)
• Commit hash: b8f5721bcddfacdd83bab43b4b47a36c3fe49b49

Steps to reproduce issue

Start the psdk. Communication is fine (I can read topics such as position_fused, gimbal_angles or successfully control the gimbal publishing on gimbal_rotation). If I try to read the distance measured by the laser range finder mounted on the payload with:

ros2 service call /wrapper/psdk_ros2/camera_get_laser_ranging_info psdk_interfaces/srv/CameraGetLaserRangingInfo "{payload_index: 1}"

Expected behavior

Read a distance of about 7.5 meters in the response to the service call.

Actual behavior

I always get success=True, but distance=0, even though I can read the correct distance (around 7.5 m) on the remote controller. The complete response is: psdk_interfaces.srv.CameraGetLaserRangingInfo_Response(success=True, longitude=0.0, latitude=0.0, altitude=0, distance=0, screen_x=0, screen_y=0, enable_lidar=False, exception=0) I tried with payload_index 2 or 3, but in that case I get success=False

Additional information

The mandatory module section in psdk_params.yaml is set like this:

      mandatory_modules:
        telemetry: true
        flight_control: true
        camera: true
        gimbal: true
        liveview: true
        hms: false
        perception: true

Are you willing to make a PR? If yes, add the PR link here.

[michele-colombo]

Hi, any info on this? Have you ever tested laser reading in a configuration similar to mine? Do I need to take any step before reading laser measurements? Thank you

[biancabnd]

Hi @michele-colombo, You are calling the service correctly with payload index = 1 if H20 is attached to the gimbal of your M300. We did test this a while ago and it was working. I am unable to test it at this moment to try and reproduce the error, but try to call the service at different ranges because we noticed a min range of 3 m. Try to point the camera closer and further away and see if you get any data. Let me know if you have any updates on this matter.

Thank you.

[michele-colombo]

Hi, thank you for your answer. The obstacle was at around 7.5m, so the min range should not be a problem. Also, as I said, on the remote controller we could correctly see the measurement from laser, so it wasn't a problem of surface not detected, either. If we will find something useful I'll update you.