## 2. First example. Relative motion

> This section provides information about diagrams:

> 2.1 Preliminaries

> 2.2 Construction

> 2.3 Further applications

## 2.1 Preliminaries

> To begin with this software it is useful to consider examples. First example is devoted to relative motion. The situation of relative motion is shown below.

> We have two fixed reference frames (Frame 1 and Frame 3), and we define motion trajectory of Frame 2 relatively toFrame 1. We wish to define parameters of relative motion of the Frame 2 with respect to Frame 3.

## 2.2 Construction

First of all we should set two fixed reference frames. We put two objects on desktop. These objects correspond to (Frame 1 and Frame 3). Then we use property editor of each object.

This editor enables us to enter coordinates and transformation matrix of reference frame. After this action we shall define formulas of Frame 2. We use the component for this purpose. Then enter seven formulas. First three define x(t), y(t), z(t) . Latest four formulas defines angular evolution (we use components of orientation quaternion). Then we put object that is a moved reference frame. Afterwards we connect all objects as diagram below

You can download this situation. Directions of arrows coincides with association direction. Arrow from Frame 2 to Frame 1 means that Frame 2 knows about Frame 1, since a position and an orientation of Frame 2 depends on position and orientation of Frame 1. However Frame 1 should not know about Frame 2. Similarly Frame 2 knows about Motion equations. Final step is to set the component for relative measurements and for graph indication of relative motion parameters. The property editor of graph indicator enables us to show parameters of relative motion as in a picture below

## 2.3 Further applications

This example is very simple. However we can use a lot of reference frames, like it is exposed on the following picture

We have relative motion and relative motion parameters of these frames. We can link a virtutal video camera, a celestial body or a spacecraft with every frame. Then we can to observe coelosphere through a virtual camera. So we have an excellent tool for virtual reality.