Unable to switch to guided mode

BlueROV2(RaspberryPi4B + NAVIGATOR)(No GPS)

I want manual control, but I can’t switch to Guided mode.
Added port:27000 with NMEA Injector.
Sending dummy data(GPGGA) to the 27000 did not go into Guided mode.
After checking, the values of GPS_INPUT(Component ID:220) lat and lon are changing.
What else should i do?

There was an article that GPS feedback is required to shift to Guided mode.
What is GPS Feedback?

In the past, ArduSub was a bit picky about the GGA messages, so make sure you are sending all of the needed values, like hdop and particularly the number of satellites value which should be something like 15 or more.

Thank you for your reply

hdop is a fixed value : 0.92…
satellites_visible is 16

  "message": {
    "alt": 15.199999809265137,
    "fix_type": 3,
    "gps_id": 0,
    "hdop": 0.9200000166893005,
    "horiz_accuracy": 0.0,
    "ignore_flags": {
      "bits": 56
    "lat": 580165000,
    "lon": -108300833,
    "satellites_visible": 16,
    "speed_accuracy": 0.0,
    "time_usec": 0,
    "time_week": 0,
    "time_week_ms": 0,
    "type": "GPS_INPUT",
    "vd": 0.0,
    "vdop": 0.0,
    "ve": 0.0,
    "vert_accuracy": 0.0,
    "vn": 0.0,
    "yaw": 0
  "status": {
    "time": {
      "counter": 65482,
      "first_update": "2023-06-01T05:11:27.383203883+00:00",
      "frequency": 0.9981859922409058,
      "last_update": "2023-06-01T23:24:48.779909821+00:00"

QGroundControl does not change.
I can’t even switch to guided mode.

Yes, if ArduSub isn’t happy with the position info it is receiving it won’t allow you to switch into guided or position-hold modes. Exactly what info it requires and in what ranges (for example, “vdop is required and must not be greater than 3.0” or some other value) isn’t documented anywhere I can find. Perhaps the BR staff could post here some example GGA messages from a system that is known to work, like the WaterLinked SBL?

We’ll need some info from @williangalvani about the requirements here, because I haven’t looked into this part of the firmware before.

From some initial searching, it seems that

Thank you for your reply

I sent GPGSA, but it was not reflected in GPS_INPUT.
The comments on “” make it sound like it doesn’t support GPGSA, including VDOP.

Even changing the value of EK3_GPS_CHECK from 31 to 0 or 3 did not lead to Guided mode.

Examine AP_NavEKF3_VehicleStatus.cpp.

I’ve checked AP_NavEKF3_VehicleStatus.cpp, but I’m not sure if it uses data received over UDP.

BlueROV2(RaspberryPi4B + NAVIGATOR)(No GPS)
How can I move to Guided mode with this configuration?
BlueROV2 settings and parameters, QGroundControl settings and whether to start, what do you need?
Should I replace NAVIGATOR with Pixhawk?

Can I switch to Guided mode with UnderWaterGPS?

Yes, and I’ve done it with a couple of different USBL systems sending GPGGA messages.

Did you find a solution to switch to guided mode without GPS? My team is currently about to deploy our submersible for initial testing today (we built a custom drone). We will be testing in manual mode initially, but I would like to make it more automated. I am running into the same issue of not being able to switch to guided without GPS. We are college students without the budget for underwater GPS systems.

If the vehicle is initially able to receive a GPS signal on the surface and enter into guided mode, will it get kicked out of guided mode when it goes underwater and loses GPS? Our team is deploying manually today, but want to try to find a workaround for this issue to set mission waypoints. We are college students with a custom-built submersible project and no budget for a sophisticated underwater gps or acoustic positioning system. Any help will be greatly appreciated.

Sadly, if you don’t have positioning, you don’t have positioning. You could run on the surface, or with a mast sticking up to keep your GPS antenna out of the water. A DVL will provide a pretty good dead-reckoning position track for awhile after you lose GPS. If you are operating in clear water, Rusty suggested to me once the idea of trying to adapt the kind of down-looking optical tracking system that quadcopters use to dead-reckon navigate after losing GPS signal much like a DVL does using inexpensive parts, but that would take a lot of work to make from scratch.

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This is for an undergrad mechatronics senior design project. It’s just proof of concept. I don’t need to go very deep. Do you think I could manage 1 meter in clear water in the manner you described? That would be good enough for me to write in the final report why we would need a larger budget to go deeper. Worst comes to worst, I will demonstrate waypoint navigation on the surface, but I would like to show that the concept works for diving, even if only very shallow.

Hi @judahwo -
I believe you’re misinterpreting @rperkins response, GPS will not work in clear water, as radio waves don’t penetrate at all! He is referring to a concept where you would setup a top-down camera, and use machine vision to estimate vehicle position, and communicate that to the vehicle. This would take a lot of work to develop, as he mentions.
If you want to use normal GPS while the vehicle is underwater, your going to need to elevate the GPS module above the water, on a stick as was suggested…

Thanks for chiming in, Tony! I agree that an above-water GPS antenna sounds like the simplest way to get this proof-of-concept demo working quickly.