How drones work an introduction, Episode two – some links and notes

A good explanation how the IMU works.


How small is the IMU

The Heart of the Drone, The IMU

At the end of episode 1 on how drones work I said I would talk about the GPS system. Well since then there has been a discussion about the first episode. You can follow it at PhantomPilots and TelloPilots, links at

We need to clarify some points and modify what I said in the first one.

The order of episodes and what they contain are going to change all the time.
So much depends upon feedback and as we discover more how drones work.
I just hope it helps you understand how drones work so you can go into more depth yourself.

Firstly, about the optical flow. I said that the two sensors black and red were responsible for optical flow. It could be that the centre camera could be the auto flow sensor and the black and red just some backup sensor.
Show Mouse

Now here is the problem. Why can’t I tell you? Because I don’t know, many don’t know. There are no simple videos out there that I can find saying for definite. DJI who are responsible for the sensors in the Tello and the Mavic’s and Phantoms have not released this information because their competitors could copy. Now I will tell you the answer in the next episode because someone is going to know for sure and tell us, I will tell youJ

Whatever the case it’s a very important sensor system in almost all drones.
But there is a sensor that is more important than the barometer. It’s amazing what it does.
In the first one I said the barometer controlled of the descent or and distance from the floor of the Tello and despite the fact that barometer go very sophisticated lately it’s not the main instrument that controls that descent. In just about all drones now there’s a very important instrument on board that’s called an IMU internal measurement unit here are some pictures of an IMU.


Image result for what does the IMU do

Image result for what does the IMU do



So, use your hand and do the 3 controls. Roll, Pitch and yaw.

But to put a physical one inside a tiny drone would be very difficult and very expensive so what drone makers do is use and electronic one a small chip that does the job more accurately and does not break as a physical one would.
Here is an IMU chip.


Tiny ehh! Amazing!
What it does is keep the drone steady in the air and controls its movement.
And it has to do this in three dimensions, just like a large aircraft.

Where else would you find IMUs? You would be supprised. Find out:)