Information on DJI drone stability and general systems wanted?

[John Gowland]

I have been trying research this question for ages the information is so difficult to find I know they use optical flow senses and a barometer, which I have a good grasp of but I can't find out how this is used on the Tello, Mavic and Phantom series.
I would very much appreciate if anyone can direct me to articles that explain how the drones can remain so solid and still for example on a patterned floor..
I know most drones uses this technology but again articles on exactly how it's implemented is difficult to find I would very much appreciate any help and finding resourses so I can understand exactly how they work. Any videos would be awesome.
Thanks

 

[Florida Drone Supply]

Obstacle avoidance has many different faces. It does more than just avoid a tree in it's path. It also detects position its position in space. They use many different types of sensors to accomplish these tasks, and the technology is only getting better.

Stereo Vision Sensors work a lot like your eyes do. You have two cameras that are seeing the same image from a slightly different perspective. Each camera has X number of pixels and the computer is constantly matching every single pixel during flight. Once they are matched up the system the triangulates it's position to then determine depth. Drones live the new Mavic 2 are using these on all sides for obstacle avoidance and determining it's position.

Ultra Sonic Sensors are used often, but typically only underneath the drone. This is an audio sensor and works exactly like a bat would see at night. These are typically only used on the bottom of an aircraft because of the distances that they can work.

I'm not an expert, but would recommend this link below that should answer a bunch of your curiosities.

12 Top Collision Avoidance Drones And Obstacle Detection Explained



HOPE THIS HELPS

 

[John Gowland]

Thanks Florida Drone Supply that is the best bit of info feedback I have had. But again I am so surprised as to how little clear, simple information there is out there how these amazing machines work in simple terms that anyone can understand.
Any more info would be great. I started out looking for a clear simple video explaining how optical flow sensors work on say a Tello. But there is so little out there.

 

[umanbean]

I am so surprised as to how little clear, simple information there is out there how these amazing machines work in simple terms that anyone can understand.

The information is not 'out there' because the technology is not 'simple'.... and 99.9% of the general public couldn't understand it even if it was published and easy to find. Most people don't use 5% of what their smartphone is capable of - because they don't understand it

 

[John Gowland]

I agree with you totally umanbean which is why I am going to make a series of vids explaining the basics. I want to know how they work and I want to share what I have learnt.

 

[N017RW]

It’s also proprietary beyond operating principals.
No schematics are published.

Several years ago a member reverse eng. the P2 schematics which proved very accurate but were not official.

 

[With The Birds]

There are plenty of simple explanations and videos available. Search for Movidius (intel) Myriad and a start. This will give you a good primer on the obstacle avoidance systems.

The basic downward VPS systems are easiest to understand in simple terms. If the pattern of what is below the cameras is moving it is simple for the flight controller to make adjustments to maintain a fixed position. It simply adjusts the outputs if the motors to move the drone in the opposite direction to the detected movement.

 

[John Gowland]

No17RW did you mean this one
DJI/Ryze Tello Drone Gets Reverse-Engineered – Sander Walters – Medium
I have trying to find it for ages but this one goes but the link goes nowhere. I would be grateful if you could find the results.

 

[John Gowland]

Thanks With The Birds that VPS system is called a Optical Flow sensor system it works on the same principle of an optical mouse powered by a 14 core intel processor and that is what I was planning for the first simple vid I will do whilst asking viewers for more info.
But I have not heard of the Movidius (intel) Myriad, that's excellent thanks so much. Awsome.

 

[With The Birds]

Thanks With The Birds that VPS system is called a Optical Flow sensor system it works on the same principle of an optical mouse powered by a 14 core intel processor and that is what I was planning for the first simple vid I will do whilst asking viewers for more info.
But I have not heard of the Movidius (intel) Myriad, that's excellent thanks so much. Awsome.

14 core processor for a mouse? That sounds like massive overkill. 14 pixel sensor perhaps... You are only dealing with simple correlation in a mouse where the sensor is at a constant distance to the tracked subject.

Movidius will become known to you very early in any research you might do on OA and tracking for the DJI products. It’s what they use.

 

[John Gowland]

Sorry With the Birds, perhaps I was not clear enough. The Tello has a 14 core CPU.
https://www.gearbest.com/blog/new-g...5251&cid=deb1ea70-bbdb-4241-bd13-5b6aca6c35f7
Thanks for the Movidius idea.

 

[N017RW]

No17RW did you mean this one
DJI/Ryze Tello Drone Gets Reverse-Engineered – Sander Walters – Medium
I have trying to find it for ages but this one goes but the link goes nowhere. I would be grateful if you could find the results.

JG,

Never looked at that link.

For what I'm referring to...
Go here:
WIP Phantom 2 PCBs, Schematics and Info

Scroll to the bottom of the first post for a link to .pdf files.

Cheers!!!

 

[John Gowland]

Thanks N017RW but way beyond what I was thinking of. I was planning on a very simple, easy to understand, vid aimed at your average person.

 

[With The Birds]

Sorry With the Birds, perhaps I was not clear enough. The Tello has a 14 core CPU.
https://www.gearbest.com/blog/new-g...5251&cid=deb1ea70-bbdb-4241-bd13-5b6aca6c35f7
Thanks for the Movidius idea.

The Tello doesn’t have a 14 core cpu. It has a Movidus myriad 2 which has 2 processor cores (CPU) and 12 video processing cores.

 

[John Gowland]

Dji says it does
Tello | Ryze Tech - Feel the Fun
Ryze says it does
Tello
DJI forum says it does
Hello Tello -Review

Movidius is a company based in San Mateo, California that designs specialised low-power processor chips for computer vision. The company was acquired by Intel in September 2016. Wikipedia
https://www.google.com.au/search?so...-1j1......0....2j1..gws-wiz.....0.RvzeXNMyzYY

On January 2018, DJI and Ryze changed the market for inexpensive quadcopters forever with the release of the Tello, a low cost micro drone which has some impressive hardware like an Intel Movidus Myriad a 12 programmable video accelerator core and 2 general purpose core VPU.
DJI/Ryze Tello Drone Gets Reverse-Engineered – Sander Walters – Medium
Intel own Movidus. It is a Intel 14 core processor 12 for video and 2 for general purpose VPU. 12+2=14, I think.

 

[John Gowland]

My problem is that I want to present a vid explaining these systems in a simple format, but I am trying to come to terms with these complex systems with so few resources out there and make it easy to understand so your next door neighbor understands but still be accurate and engaging. Like the two cores dedicated to the VPU. Now I think that means the Optical Flow system. But are the two downward sensors on the Tello Infrared Optical Flow? Or are there two independent systems?
"The IR sensors on the Tello help with smooth takeoff and landing as well as palm launch and downward obstacle avoidance, while Optical Flow keep the drone super stable."
DJI/Ryze Tello Drone Gets Reverse-Engineered – Sander Walters – Medium

I know the Mavic uses Ultrasonic downard sensors as does the Phantom 4s
"There are 3 stereo vision sensors, 2 ultrasonic sensors and 2 infrared modules on the Phantom 4."
Calibrate Vision Sensors On The Phantom 4 To Fix Errors
Not an easy task to comprehend this stuff and get it across in a simplified way.
Thanks for your Input With The Birds.

 

[With The Birds]

Dji says it does
Tello | Ryze Tech - Feel the Fun
Ryze says it does
Tello
DJI forum says it does
Hello Tello -Review

Movidius is a company based in San Mateo, California that designs specialised low-power processor chips for computer vision. The company was acquired by Intel in September 2016. Wikipedia
https://www.google.com.au/search?so...-1j1......0....2j1..gws-wiz.....0.RvzeXNMyzYY

On January 2018, DJI and Ryze changed the market for inexpensive quadcopters forever with the release of the Tello, a low cost micro drone which has some impressive hardware like an Intel Movidus Myriad a 12 programmable video accelerator core and 2 general purpose core VPU.
DJI/Ryze Tello Drone Gets Reverse-Engineered – Sander Walters – Medium
Intel own Movidus. It is a Intel 14 core processor 12 for video and 2 for general purpose VPU. 12+2=14, I think.

4+4+7+8=23, I think.
Yes John 12+2=14 the question is 14 what?

By simple definition a CPU handles instructions that aren't completed by a specialised processing units. In then case of the Myriad 2 it contains 2 CPU's and 12 specialised processing units called vector VLIW processors. Have a look at the third link you posted- the distinction between general CPU and video accelerator core seemed important to them (based on your quoted text- I haven't followed the link to read the article).

The Apple A12X SOC contains 4 "Performance" and 4 "Efficiency" CPU cores with 7 GPU cores. The A12X also contains an additional 8 core "neural engine". Do we say its a 23 Core CPU? Most wouldn't and that seems reasonable no matter how simple one might like to keep things.

 

[With The Birds]

Like the two cores dedicated to the VPU. Now I think that means the optical flow system.

What it means is two general CPU cores with 12 specialised programmable cores.

Optical flow is just nice marketing lingo, like lightbridge. For the purpose of your simple explanation why not just say the drone can maintain its position by watching the ground with a dedicated camera and automatically adjusting its flight controls if it sees movement?

If your intent is to explain to your neighbour how a drone might manage to hold station and avoid colliding with things in a simple way you might have a better chance of success if you avoid the specifics of the SOC architecture.

 

[John Gowland]

Your right With the Birds no way can I go into such depths. But all the advertising like the most popular schematic image says Intel 14 Core and I have to stick with that even though you correctly pointed out is not the full story. Optical Flow turns up a lot when you start to dig down and it can start to explain in simple terms what is happening keeping the drone stable. Sometimes marketing lingo is helpful sometimes darn-right unhelpful.
That Moore guy has a lot to answer for I reckon. Thanks for your clarification With the Birds.

 

[With The Birds]

Your right With the Birds no way can I go into such depths. But all the advertising like the most popular schematic image says Intel 14 Core and I have to stick with that even though you correctly pointed out is not the full story. Optical Flow turns up a lot when you start to dig down and it can start to explain in simple terms what is happening keeping the drone stable. Sometimes marketing lingo is helpful sometimes darn-right unhelpful.
That Moore guy has a lot to answer for I reckon. Thanks for your clarification With the Birds.

If your interested in the right simple story this might be a good source Hello Tello - Ryze Announces Intel Myriad VPU Powered Toy Drone | Machine Vision Technology | Movidius

The Tello story is well known. They collaborated with intel and DJI to port the DJI flight control code onto the Myriad chip.

That is a great story....