Question on Tello vision positioning system

[GoTello]

Hi all - I've bought my tello for a couple of months ago but just now notice that there's only one red light of the vision positioning system on (this can be seen when I active the quad and turn it upside down). I wasn't sure if it's supposed to have two red lights on instead of one when flying. Also my tello now seems to shift easily when hovering. Does anyone know if one red light is normal or how I can solve this problem?

Thank you in advance!

 

[Ansia]

This is normal. One of the sensors sends the signal (red light) and the other receives it. Do an IMU and gravity calibration. Should. Fix your problems.

 

[GoTello]

This is normal. One of the sensors sends the signal (red light) and the other receives it. Do an IMU and gravity calibration. Should. Fix your problems.

Thank you Ansia!

 

[sunny_sahdev]

Hi all - I've bought my tello for a couple of months ago but just now notice that there's only one red light of the vision positioning system on (this can be seen when I active the quad and turn it upside down). I wasn't sure if it's supposed to have two red lights on instead of one when flying. Also my tello now seems to shift easily when hovering. Does anyone know if one red light is normal or how I can solve this problem?

Thank you in advance!
View attachment 2051

This is pretty normal as checked mine as well, Kindly calibrate and hovering will be fixed.

 

[GoTello]

This is pretty normal as checked mine as well, Kindly calibrate and hovering will be fixed.

Thank you!

 

[umanbean]

Also my tello now seems to shift easily when hovering.

I'm a new Tello owner, but I've noticed it hovers more stable over a patterned or irregular colored surface, and not as well over a solid color surface. Try it, you'll see a difference.

 

[GoTello]

I'm a new Tello owner, but I've noticed it hovers more stable over a patterned or irregular colored surface, and not as well over a solid color surface. Try it, you'll see a difference.

Very good to know, I will try it. Thank you umanbean!

 

[Netfolks2000]

I've searched on Google and here in the forum to see how those underbelly sensors work. Can anyone explain how the three spots on the belly of the Tello function for stability of the drone? Why are there TWO LEDs? Why does only one light up as mentioned above? If one sends the signal to the ground what does the other LED do? I don't think an LED can RECEIVE anything since they emit, not receive. What is that middle "thing"? Is it the receiver? Does one LED send a lighted emission and the other some other kind of infrared? Interesting technology. Someone please explain the function of those three components. Thanks.

 

[umanbean]

Reading the owner's is a good idea. You can download it from the DJI website.

 

[Netfolks2000]

Reading the owner's is a good idea. You can download it from the DJI website.

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I sincerely appreciate that as a reply but I am still seeking the actual technical description of how the visual positioning really functions. I'd enjoy reading that. It is an amazing feat.

 

[Netfolks2000]

I sincerely appreciate that as a reply but I am still seeking the actual technical description of how the visual positioning really functions. I'd enjoy reading that. It is an amazing feat.

From what I've searched here on the forums it appears that the two LEDs underneath send light to the ground. It is infrared. You can see it if you take a photo with your phone. BUT.... it only comes from one of the LEDs. I've read that one sends and the other LED receives. Although I thought LEDs only emitted light, not receive it. Still there is the camera in the middle. I would think it is what receives and analyzes the image to determine position. Anyone have further explanation on how this works?

 

[liz]

Infrared light bounces back from the ground In order to be received by the receiver. Similar to a tv remote control. When the Tello is too near an object below it it seems the light will complete the circuit causing the drone to rise in elevation to avoid the perceived obstacle. The positioning system utilizes a snapshot of the area underneath if I recall correctly. And this snapshot is referenced in hover allowing the drone to realign itself to the appropriate location, this is why this function tends to fail in low light because the image quality the drone uses to realign itself is not sufficient in low lighting.