‫Welcome back.
‫In this lecture, we will start with kinematic equations, and the first thing that I'm going to teach
‫you is how to describe the position of a drone with respect to the inertial frame.
‫And after that, we're going to move on on to rotational matrices and we're going to use them to describe
‫the attitude of the drone.
‫Let's just take a concrete example and build the intuition around it.
‫Let's take our drone, which is right here.
‫Our goal is to be able to describe the position and the attitude of the drone in a 3D space for that.
‫As mentioned before, we're going to define two reference frames.
‫One will be the inertial frame or earth frame, which is fixed to the ground and which doesn't move.
‫And the other one will be the body frame that we attach to a drone and that moves with the drone.
‫It's very easy to describe the position of the drone in a 3D space.
‫You do it with a position vector that goes from the origin of the inertia frame to the origin of the
‫body frame.
‫That position vector has three elements which are X, Y and Z.
‫We are going to call this vector P.
‫That means that P can be written like this P vector equals and then you have some kind of X dimension,
‫some kind of Y dimension and then some kind of Z dimension.
‫Remember, you can put that fixed reference frame wherever you want and then you simply measure the
‫origin of the body frame relative to it.
‫Let's do a small exercise.
‫So you have a house and you choose to put an inertial frame in this lower right corner and now you have
‫two drones hovering, drone one and drone two.
‫All the distances that you need are denoted with the letters A, B, C, D, E and F, and here you
‫have the distances in terms of meters.
‫Knowing all that, what is the position of the drones in terms of their position vectors with respect
‫to this inertial reference frame?
‫Tried yourself and then in the next video you will see the answers.