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I am working on a project where I need a quadcopter to accurately know its location relative to a starting point in a GPS denied environment in the dark.

A quick overview of the project:

  • The drone will be mounted on a vehicle in a docking station
  • When prompted, the drone must hover above the vehicle by ~30 m
  • The drone must be able to accurately locate its position relative to the docking station in the dark without GPS
  • The drone must also be able to react to the movement of the vehicle (very small movements in nature)
  • When finished, the drone will return to the docking station

Given the requirements of the problem I have been looking at a couple of solutions:

  1. Use around 3 infrared beacons on different parts of the vehicle with a camera on the drone to perform localization (looking at the IR-LOCK sensor and beacons for this purpose)
  2. Use ultra-wideband communication with a similar setup of three or so anchors and one receiver on the drone (looking at the Pozyx anchors and tag)
  3. Use Bluetooth of some sort (haven't looked into this one as much)

Any suggestions or tips you may have would be greatly appreciated. My main concerns are the range/feasibility of each option.

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    $\begingroup$ Generally, avoid asking what is "best". There is no canonical answer to that, and SE sites in general are not well formatted for the rambling conversations which arise from this kind of question. If you can, try to reformulate to ask specific questions about how to accomplish something, such as "How can I navigate in the dark in a GPS-denied environment?" $\endgroup$ Sep 22 '20 at 16:20
  • $\begingroup$ I have played around with bluetooth and proximity/location calculations - this was pretty much a dead end - the results will not be accurate enough to safely land your drone. Option 1 sounds good if you can make sure that you will always maintain line of sight to your beacons. From what I remember Pozyx has a rather low update rate - not sure if this will be enough for your project. $\endgroup$
    – stylesuxx
    Sep 23 '20 at 19:44
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    $\begingroup$ Are you asking about equipment a hobbyist could buy off the shelf, or technologies that a small aerospace company could develop? $\endgroup$ Sep 30 '20 at 8:06
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With sufficiently accurate and stable IMUs (think ADIS 164xx) on both vehicle and drone you should be able to calculate the relative offset between the two. In any way this will have to be a custom solution.

What GPS denied environment are you referring to?

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"GPS denied" as in "not allowed"? GPS is without client transmission so it should be legal everywhere...

Anyway, for proximity while landing, the drone can shine a light down at the vehicle to illuminate a QR code like pattern. This could tell the drone "the docking station is 20cm to the front".

Another way for precise landing would be RFID. This tech only has a small range, thus it is very precise.

LiDAR could be useful for obstacle avoidance as well as a 3D model of the surroundings (can be expensive though - I don't know about your budget).

Also, bats navigate with echoes. Maybe this could be interesting - I highly doubt that however.

Another idea: corner cube reflectors. I can recommend these two videos: 1, 2. These mirrors reflect the light in whichever direction it is coming from. With very short and quick measurements, you can measure distances very precisely. Again: it's probably quite cost-intensive.

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