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It seems that Ingenuity has a 4000 pixel camera, a gyro, inclinometer and an altimeter. Using these information, they are able to derive three axis velocity information. Thereby compensating for the inability to put a doppler velocity instrument.

In Page 11 of Mars Helicopter Technology Demonstrator (also here 1, 2):

This processor implements visual navigation via a velocity estimate derived from features tracked in the VGA camera, filter propagation for use in flight control, data management, command processing, telemetry generation, and radio communication.

I have two questions basically,

  1. How are they able to do that? I am looking for the algorithm/equations used. Are they looking at pixel shift or some ML algorithm is implemented?
  2. What are the accuracies compared the traditional doppler velocity instruments in landers at the height where ingenuity will operate.
Cornelis
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zephyr0110
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  • great question!! – uhoh Feb 28 '21 at 07:20
  • @Prakhar This doesn't answer your question at all, but there's a little discussion about 8 mins in: https://www.youtube.com/watch?v=GhsZUZmJvaM – Roger Wood Feb 28 '21 at 09:56
  • Optical flow is supposed to be pretty simple. – ikrase Feb 28 '21 at 09:58
  • @ikrase. Yeah but then there is this problem if being inclined and separating motion due to rates and actual velocity.. It isnt as trivial as far as I think. Cant think its even analytical solvable – zephyr0110 Feb 28 '21 at 09:59
  • If they have a good IMU, three axis rotational velocity information and two axis attitude is fairly trivial. Does it really not have an accelerometer? – ikrase Feb 28 '21 at 10:05
  • It has MEMS gyro. Yeah Its trivial if you assume rate info to be precise and attitude to be precise. But it should be some sort of KF estimation I guess. – zephyr0110 Feb 28 '21 at 10:07
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    "A few dozen features are compared frame to frame to track relative position to figure out direction and speed, " https://spectrum.ieee.org/automation/aerospace/robotic-exploration/nasa-designed-perseverance-helicopter-rover-fly-autonomously-mars – Cornelis Mar 03 '21 at 18:06
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    That is a good read @Cornelisinspace – zephyr0110 Mar 04 '21 at 10:52

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