Will GPS-for-yaw work far offshore? [yes]

ArduCopter
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1

Hello,

I am planning to use a VTOL on the deep sea in the South Pacific, equipped with two CUAV c-RTK 9PS GPS (C-RTK 9Ps Centimetre-Level GNSS Module – CUAV 雷迅创新). However, I have a question regarding its ability

The VTOL I am purchasing uses two GPS to calculate the heading instead of a compass due to magnetic interference from the ship. However, I am uncertain whether the RTK GPS will function normally on the deep sea, as there is no nearby land and thus no ground station. Would it be sufficient to use a mobile ground station?

As I have limited knowledge on this topic, any help or advice would be greatly appreciated. Thank you.

edited : we will use ground base station.

2

Moving baseline configurations (GPS-for-yaw) work independent of any fixed base. You don’t need one unless you also desire precisely corrected position, in which case, I can’t help with how that might work on a boat.

3

Thank you for letting me know that GPS-for-yaw works independently of any fixed base.

However, I’m curious about what happens when RTK is not available in the deep sea of the South Pacific. Does GPS-for-yaw get disabled in such cases?

4

The (onboard) moving base GPS provides corrections to the rover GPS. It generates its own RTCM3 messages. It should work nearly worldwide. You are needlessly conflating moving baseline configurations (onboard relative positioning) with fixed base operations (off board corrections for absolute positioning).

5

Moving baseline configurations (GPS-for-yaw) work independent of any fixed base.

← thank you. but my seller said GPS-for-yaw function disabled when RTK signal is lost.

is that correct? maybe my GPS module have no magnetometer inside.

6

That’s just simply misleading.

Moving baseline configurations are self-contained. They work regardless of the availability of any external correction source or magnetometer. Therefore you can expect GPS-for-yaw to work even in the middle of the Pacific.

If ONBOARD GPS performance is poor for some reason, and the ONBOARD module cannot provide ONBOARD corrections, the yaw feature will fail. I would expect that only to be the case at extreme polar locations or during significant jamming or solar events.

7

I’m sorry, but I don’t understand. Could I please ask a few questions to clarify?

You mentioned that “the (onboard) moving base GPS provides corrections to the rover GPS.” Can you please explain what the rover GPS and onboard GPS are? Do you mean that two GPS systems on the airplane will correct each other?

Or do you mean that the ground base station GPS will correct the airplane GPS?

If you mean the former, then that sounds like a good system. However, I just want to make sure that I understand correctly.

Thank you for your patience and assistance in helping me better understand.

8

I did some research and found that in the context of RTK GPS,

I found “rover GPS” means “moving gps on airplane”,
and “moving base GPS” means GPS on ships.

I understood what your meaning. with base ground mobile stations, it should work nearly worldwide.

9

You still have some misunderstanding.

A moving baseline configuration (otherwise known as “GPS for yaw” in this context) consists of two onboard GPS modules: one is the moving base, and the other is the rover. The moving base (ON THE AIRPLANE) provides the primary positioning data for the vehicle, and it provides RTCM3 corrections to the rover (ALSO ON THE AIRPLANE) such that the rover is precisely located RELATIVE to the moving base. As such, yaw can be determined independent of any external correction source. You do not need any GPS on the ground (or ship) for this to work, and the availability of an external RTCM3 source is irrelevant. Thus, GPS-for-yaw works worldwide, even in the middle of the ocean.

While I do not have experience with CUAV manufactured hardware, they feature well proven uBlox Zed-F9P modules and should function quite well for the chosen application.

10

Thank you for your response. I will reach out to the manufacturer (CUAV) to confirm whether this information applies to their GPS system. As I have limited knowledge about this technology, I want to ensure that It is samely applicable to CUAV GPS.

Nevertheless, I am hopeful that this technology will perform well in the challenging conditions of the South Pacific.

Once again, thank you for taking the time to explain these concepts to me. Your kind explanation helped me very much

11

There is no reason whatsoever that it would not apply to CUAV hardware. Please refer their service representative to this specific discussion to hopefully avoid translation errors.

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