Drone losing position / crashing in Offboard mode

[Jetson Nano]

@Eric-Katzfey when I do

voxl-inspect-mavlink mavlink_onboard

I am getting

and in mavlink console when I stream Odometry message as you said I am getting no output

when I used -d instead of -u it shows device not running. I tried with different ports

[Jetson Nano]

Hey @Eric-Katzfey , I think I solved it. I got the odometry stream to VOXL2 from Cube. I had to run

mavlink stream -r 30 -s ODOMETRY -d /dev/ttyS0

after this I got odometry stream on the

voxl-inspect-mavlink mavlink_onboard

[Eric Katzfey]

@Jetson-Nano Great! And is that now allowing you to run the figure 8?

[Jetson Nano]

@Eric-Katzfey I haven't done the flight test. I'll do the flight test and get back to you.

[Jetson Nano]

@Eric-Katzfey , I did the flight test and it works fine. Thank you.

But there is a problem, when I am checked 1st time it worked fine, later after a reboot and once again I ran the Mavlink Odometry stream, the terminal was lagging. The terminal with the output of voxl-inspect-mavlink mavlink_onboard this is lagging. The Odometry Hz was somewhere around 5 - 10, all the output in the terminal was lagging, so I though it was some WiFi issue and again tested offboard mode, but this time the drone went back to home.

So I rebooted the system and again ran the mavlink stream and waited for sometime until the lag in the voxl terminal is not there anymore, then when I tested offboard it was fine. I tried both figure eight and trajectory, both worked fine. I will attach the logs, can you please tell what might have caused the lag?

https://logs.px4.io/plot_app?log=93fb987f-c326-4d5d-89bb-2771bcacb3fc

https://logs.px4.io/plot_app?log=593bdb7b-7ce5-45f5-b183-2d0914015162

https://logs.px4.io/plot_app?log=3d8e8bd4-ec6e-4bcf-beea-741dff891ff9

https://logs.px4.io/plot_app?log=d33b6610-af39-4006-b90e-d1fdaad75da7

https://logs.px4.io/plot_app?log=b1ac6a04-0e1a-4049-bc27-dfe9a25224a8

[Jetson Nano]

And I have one more question @Eric-Katzfey , I have to start the mavlink stream everytime. Is there a way to start the mavlink stream as soon the system is powered on?

[Eric Katzfey]

@Jetson-Nano Yes, there is a way to do that. Probably best to consult the PX4 documentation or ask on the PX4 forum for best way to do that on a Cube Orange.

[Jetson Nano]

@Eric-Katzfey What about the previous question I asked?

[Eric Katzfey]

@Jetson-Nano I really don't know what would cause that lag. You say it goes away if you wait awhile. How long do you have to wait for that to happen? And what is the baud rate of the UART that connects the CUBE Orange to VOXL 2? It's possible that the UART has too much data going over it and needs a higher baudrate.

[Jetson Nano]

@Eric-Katzfey The baudrate is 921600, sometimes I'll have to wait for more than 5 minutes and sometimes within seconds it will be ready to fly with required Hz

[Eric Katzfey]

@Jetson-Nano Part of the startup sequence when running with QGC or MP is to upload a full set of parameters. There are hundreds of parameters and this can take quite a while to complete. While this is happening the serial link is inundated with PARAM_VALUE mavlink messages. Once that has been completed then the link will have much less traffic. While it is laggy you can look at the mavlink console and see if it is receiving those PARAM_VALUE messages. That is a possible reason.

[Jetson Nano]

@Eric-Katzfey I'm currently integrating VOXL2 with Flight Core V2.

PX4 version: v1.14.3 (from modalAI fork)

I am trying to use offboard mode and do figure-eight, but the problem I'm facing is, whenever I switch to offboard, the drone sometimes moves randomly.

Once I reboot the FC once and start flying from same position, and then switching to offboard, I observe that the drone does figure 8, but loses height sequentially and drifts over the ground and crashes after a few cycles.

For height estimation, I rely on using a Rangefinder.

Also, when I run,

voxl-inspect-mavlink mavlink_onboard

I'm not able to observe, the #331 ODOMETRY message.

[Eric Katzfey]

@Jetson-Nano What happens if you don't use the rangefinder? If VIO is working then you get the height from that.

[Jetson Nano]

@Eric-Katzfey Thanks for reverting back.

I had tried earlier disabling the Rangefinder and relying only on VIO.

VIO works fine in feature rich environment, when it crosses low-feature environment, there is a random motion of system which could observed serving the main reason for using external Rangefinder.

Also, height estimation goes off even if the drone does figure-eight within offboard, height estimation goes off.

Is there any way I can view the #331 ODOMETRY message being pushed from FC to Compute?

[Jetson Nano]

Hey @Eric-Katzfey I was able to solve it. I was able to shift the drone to offboard-mode, the drone doesn't drift away. In voxl-vision-hub, I have the set the parameter to figure_eight.

I'm getting the stream to VOXL2 from Flight Core v2. I had to run it on 2 different ports.

mavlink stream -r 30 -s ODOMETRY -d /dev/ttyS4
mavlink stream -r 30 -s ODOMETRY -d /dev/ttyS6
But I'm getting the #331 odometry message when using only ttyS6 port.

Now the drone is able to figure_eight loop without loosing height estimates.