Optical Flow - with or without rangefinder? Supplement to GPS position?

I’m trying to configure and understand my Cube Pilot HereFlow.

One possible mission will be indoor navigation by STEM students. It’s not clear to me now that this is possible.

Reading the CubePilot wiki about the HereFlow, it’s fairly pessimistic about the HereFlow’s lidar performance. In fact the document says for accurate navigation, a better lidar rangefinder is recommended.

Is the HereFlow’s lidar capable of supporting FlowHold flight mode at altitudes within the rangefinder’s range? (indoors)

And what happens if this range is exceeded? (outdoors) Another place in the wiki states that a copter can’t climb past the maximum rangefinder range to avoid an EKF3 failsafe.

The ArduPilot wiki on Precision Landing focuses on the IR-Lock sensor. I got the impression that an optical flow device can also be used - but I couldn’t find any details.

Without a supplemental rangefinder with greater range, I’m wondering now what is the intended use of the HereFlow. Can it be used just for precision landings?

Lastly - I seem to recall that there is an ability to used optical flow to supplement GPS in flight modes such as loiter - but I’m not finding info about that in the docs. If there is such an option, would someone please point me in the right direction to learn about it?

Thanks!

I’m curious to here more details about these questions, from my understanding Hereflow and Ir-lock landing were 2015 era…

I put a Matek flow on one quad but never got it working to my liking.

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Additional Notes

  • As with the PX4Flow sensor a range finder is required to use the sensor for autonomous modes including Loiter and RTL
  • FlowHold does not require the use of a rangefinder

Use the Hereflow and add an inexpensive range finder like a TF-Luna good for 8m. It’s all Indoors right?

Thanks Dave - that’s very helpful.

I need to get a better understanding of how optical flow is used by Ardupilot. I really appreciate your assistance.

I picked up from the wiki that FlowHold doesn’t require a rangefinder. But it’s not clear to me how FlowHold works differently if you do have a range finder. Does it work so much better that it’s worth the trouble of adding a suitable rangefinder?

And what other flight modes are affected when using an optical flow sensor with a rangefinder?

The TF-Luna looks excellent - and it’s both lightweight and inexpensive. It has a range of 8 meters - so yes, good for indoor use.

I have a Lightware LW20/C on my shelf. I could patch that thing on while I’m learning the ropes. And it uses I2C - which saves a UART.

I’m trying to figure out why the HereFlow includes it’s rangefinder. What sort of application is there for this product alone?

Thank so much for your help!