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‫Welcome back.

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‫In this lecture, we will start with kinematic equations, and the first thing that I'm going to teach

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‫you is how to describe the position of a drone with respect to the inertial frame.

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‫And after that, we're going to move on on to rotational matrices and we're going to use them to describe

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‫the attitude of the drone.

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‫Let's just take a concrete example and build the intuition around it.

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‫Let's take our drone, which is right here.

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‫Our goal is to be able to describe the position and the attitude of the drone in a 3D space for that.

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‫As mentioned before, we're going to define two reference frames.

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‫One will be the inertial frame or earth frame, which is fixed to the ground and which doesn't move.

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‫And the other one will be the body frame that we attach to a drone and that moves with the drone.

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‫It's very easy to describe the position of the drone in a 3D space.

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‫You do it with a position vector that goes from the origin of the inertia frame to the origin of the

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‫body frame.

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‫That position vector has three elements which are X, Y and Z.

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‫We are going to call this vector P.

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‫That means that P can be written like this P vector equals and then you have some kind of X dimension,

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‫some kind of Y dimension and then some kind of Z dimension.

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‫Remember, you can put that fixed reference frame wherever you want and then you simply measure the

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‫origin of the body frame relative to it.

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‫Let's do a small exercise.

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‫So you have a house and you choose to put an inertial frame in this lower right corner and now you have

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‫two drones hovering, drone one and drone two.

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‫All the distances that you need are denoted with the letters A, B, C, D, E and F, and here you

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‫have the distances in terms of meters.

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‫Knowing all that, what is the position of the drones in terms of their position vectors with respect

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‫to this inertial reference frame?

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‫Tried yourself and then in the next video you will see the answers.