I can't see OBSTACLE_DISTANCE on QGC

[rogerli]

I am attempting to use VOXL2 to connect to an external flight controller for collision prevention. I can see the information from voa_pc_out on VOXL2, but I am unable to see the information from OBSTACLE_DISTANCE on QGC. VOXL2 is connected to the telemetry 2 port of the external flight controller via UART. Here are my MAVLink parameter settings:
MAV_1_CONFIG : TELEM 2
MAV_1_FLOW_CTRL : Auto-detected
MAV_1_FORWARD : Disabled
MAV_1_MODE : Onboard
MAV_1_RADIO_CTL : Enabled
MAV_1_RATE : 0
SER_TEL2_BAUD : 921600
COM_OBS_AVOID : Enabled

On the VOXL2, it is connected to the USB/UART add-on board at J3, and the parameters in the voxl-mavlink-server.conf file are set as follows:
{
"primary_static_gcs_ip": "192.168.8.10",
"secondary_static_gcs_ip": "192.168.124.197",
"onboard_port_to_autopilot": 14556,
"onboard_port_from_autopilot": 14557,
"gcs_port_to_autopilot": 14558,
"gcs_port_from_autopilot": 14559,
"en_external_uart_ap": true,
"autopilot_uart_bus": 1,
"autopilot_uart_baudrate": 921600,
"en_external_ap_timesync": 1,
"en_external_ap_heartbeat": 1,
"udp_mtu": 0,
"gcs_timeout_s": 4.5
}

Then, when I use the "mavlink status" command on QGC to check, I see that the rx loss is 63.1%, why is this problem happening? How can I resolve it?"

[Moderator]

Have you verified the voltage level of your UART match?

[rogerli]

@Moderator
The external flight controller I am using is Cube Orange+. The voltage level of UART on both the USB/UART add-on board at J3 and the Cube Orange+ telemetry port (telem2) is shown in the image below
add-on board:

cube orange+:

[Vinny]

Hi @rogerli
Are you only connecting the UART and GND?
You need a 2-2, 3-3, and 4-6 cable.
Not sure what the CUBE connector is, but maybe our https://docs.modalai.com/cable-datasheets/#mcbl-00067 will work for you?

Be sure the 3.3V and 5V is not connected.
Hope this helps.

[wilkinsaf]

Shot in the dark I would turn off MAV_1_FORWARD if it is enabled.

Also, do you have any other mavlink based device that is connected? If so I would unplug it to see if this helps resolve the issue

[rogerli]

I only connected UART and GND, and VOXL2 is only connected to the Cube Orange+, a WiFi dongle, and a stereo camera.

I can use the "listener obstacle_distance" command on QGC's MAVLink console to obtain depth information about obstacles, and I have successfully enabled collision prevention for the drone in position mode. However, I still cannot see "obstacle_distance" on the MAVLink inspector.

[Eric Katzfey]

@rogerli What messages do you see in mavlink inspector?

[rogerli]

@Eric-Katzfey said in I can't see OBSTACLE_DISTANCE on QGC:

mavlink inspector

This is the messages I see in the MAVLink inspector.

[Eric Katzfey]

@rogerli The OBSTACLE_DISTANCE Mavlink message is based on the obstacle_distance_fused topic. Can you do listener on that topic to see if it is being published?

[rogerli]

@Eric-Katzfey said in I can't see OBSTACLE_DISTANCE on QGC:

No, I am unable to use the listener command to see the obstacle_distance_fused message. How can I enable this feature?

[Eric Katzfey]

@rogerli What is the parameter CP_DIST set to?

[Inverse AJ]

@Eric-Katzfey I am having a similar problem, where I can see obstacle_distance, but not obstacle_distance_fused using the listener command. When I checked CP_DIST it was set to -1 so I set it to 1 and then I could briefly see both with the listener command, and was able to see obstacle_distance using the mavlink inspector. After unplugging then replugging in my pixhawk, this was gone and I was back to only being able to see obstacle_distance with the listener command. Was there something that could've changed during my restart? I checked CP_DIST and it was still set to 1 even afterwards.

The only notable differences between my system and the original users is that my connection is across ethernet.

[Eric Katzfey]

@Inverse-AJ A quick look at the code shows that CP_DIST has to be greater than 0 and current flight mode has to be manual position mode. What flight mode are you in?

[Inverse AJ]

@Eric-Katzfey I was previously in "Hold" mode, but I tried in "manual" and still am not seeing the obstacle_distance_fused message. I noticed one other difference in my parameters which is that COM_OBS_AVOID doesn't exist for me.

Another question, I had previously re-flashed the Pixhawk firmware after changing the file: "PX4Autopilot/src/modules/uxrce_dds_client/dds_topics.yaml". I had added the following to the publications section:

• topic: /fmu/out/obstacle_distance_fused
  type: px4_msgs::msg::ObstacleDistance

However, it had no effect so I reverted back to the default px4 firmware shown on QGC. Is that change necessary to see the message or should I leave the default?

[Inverse AJ]

@Eric-Katzfey Small update. I also tried it with the custom firmware with that additional publication added (from previous reply), and the result has not changed. obstacle_distance_fused still shows up as "never published" when using the listener. However, with the custom firmware I get warnings from QGC about missing parameters: BAT1_V_LOAD_DROP, BAT2_V_LOAD_DROP, and COM_OBS_AVOID. I pulled the most recent main branch for the PX4 Repository to build it, so maybe there's not support by QGC yet?

[Eric Katzfey]

@Inverse-AJ Have you asked this question on PX4 forum? https://discuss.px4.io/c/px4/25

[Inverse AJ]

@Eric-Katzfey I had not since this discussion was the closest I could find to my issue. But I have created one now: Cannot see obstacle_distance_fused on QGC