title_body: How does Amazon's new drone land itself into a station? I am fairly interested in drone building and thought about a drone which automatically recharges itself by flying in to his station, but thought it was close to impossible without using extremely sophisticated tech that extremely pricey (D-GPS).
  How can this low cost drone reliabely land in its small station? Can anyone guess how?
  (this is the drone im talking about https://www.youtube.com/watch?v=EIQTR4qCoHU)
upvoted_answer: Remember - it only takes 3 points to get a solid fix on location in 3 dimensional space. I have been thinking about this a lot, I will also have a unit on day 1 and possibly the unit disassembled day 2 and posted on line (maybe)
  For the Amazon device there is most likely a sonar/echo or similar system that creates a feedback loop for position. I also suspect use of RFID or similar &quot;near proximity tech&quot; to get the last few inches.
  There are a lot of systems available and affordable, LIDAR in particular is really cheap (https://www.getfpv.com/matek-optical-flow-lidar-sensor-3901-l0x.html)
  The tech is pretty standard and accessible, Roomba has been doing this in 2D space for almost 20 years with self docking features for the floor cleaning system.
  Once you have experience with auto-leveling and GPS technology the task becomes trivial. The hard part is universality and compliance - will it work anywhere and also be legal/interfering.
  There are still a number of unanswered questions - but form what I know here a few of the approaches that come to mind:
  
  Echo location indoors (bouncing signals to determine position, similar to how the blind or bats can &quot;see&quot; using echos and reflection of sound)
  LIDAR with some GPU strength and the addition of hyper- or hypo-visible light can create an invisible beacon.
  Various systems for mapping, used commonly in drones for recovery operations such as mineshaft exploration, possibly offset to cloud computation.
  Wifi stereo has a lot of research in phasing and image control of sound worth considering.
  RFID or Bluetooth beacon technology, possibly with other AWS devices in house?
  Augmented indoor GPS (using what signal is available + other systems)
  Final landing could be simple optics targeting a unique pattern, key for orientation (downward simple camera looking for landing beacon)
  Sonar, like a bat, can help with direction, distance, and obstacle avoidance beyond aforementioned echolocation.
  Additional off-device processing - such is the case for Alexa, Siri, and other services.
  
  Also note how the female receptacle is wide and allows the unit to dock with +/- 1 inch accuracy.
  Also important, the FAA claims to have NAS authority indoors, but they have never been able to asset any enforcement action.
  This device is a HUGE blow to the FAA's weakening grasp on NAS policy. The laws that regulate this device are NOT settled and the legality is open for debate. Per the Congressional charter, the FAA controls all airspace &quot;0inch and up&quot; and there has never been any official clarification for indoor operation.  A lot of questions remain unanswered.
  FWIW, if f you fly this unit out of the house it is $40k minimum fine for violation of key BVLoS rules such as remote operation w/out spotter and BVLoS operation without an exemption.  There are many other rules, each $20k each per violation should anyone take this out to the porch. See and avoid is not met by the device and that one is huge and is the massive thorn FPV faces for proper recognition.  I will be following this close.