CAD system is an automated system that implements information technology while building or design. It is a logistical system for the automation of the design process, consisting of complex hardware, software or other automated its activities. Such systems widely use abbreviation CAD.
AutoCAD – two-and three-dimensional computer-aided design and drafting, developed by Autodesk. The first version of the system was released in 1982. AutoCAD is based on used in engineering, construction, architecture and other industries. The program is available in 18 languages. The level of localization varies from full adaptation to transfer only help documentation. The Russian version is localized in full, including the command line interface, and all the documentation, except programming manuals.
Early versions of AutoCAD operated a small number of elementary objects such as circles, lines, arcs and text. This has earned the reputation of “electronic Cool man”. AutoCAD is very broad and far superior (Ozler, 2011).
In the two-dimensional AutoCAD still allows to use the basic graphics for more complex objects. In addition, the program provides a very great opportunity to work with layers and annotative objects (dimensions, text, names). Using the mechanism of external link (XRef) allows to split the drawing into its component files, which are responsible for various developers. Dynamic blocks are used for automation of 2D-designing without programming. Beginning with the 2010 version of AutoCAD supports two-dimensional parametric drawing.
Geometric constraints establish and maintain geometric relationships between objects, key points on objects and between objects and the coordinate system. Pair of key points between objects can be as limited vertically or horizontally in the current coordinate system. For example, it is possible to specify that the two circles must always be concentric, that two lines should always be parallel or that one side of the rectangle is always horizontal. Geometric relationships are defined in the panel tab strip which is called “Geometric Parametric”. It is possible to appoint the restrictions by the cursor on display and it remembers what limits have been chosen. Dimensional constraints impose restrictions on the dimensioning geometry. For example, it is possible to use the dimensional constraints to specify the radius of the arc, the length of the line or the fact that two parallel lines are always at a distance of 15 mm. from each other. Changing the values of dimensional constraints entails a change in geometry (Braunschweig , Breitling, 2006)
It is possible to create dimensional constraints oof the panel Dimensional Parametric tab. There are seven types of dimensional constraints such as linear, oblique, vertical, horizontal, radial and diameter (Chum, Kruper, Guest, 2000)
In fact, it is possible to convert traditional dimensions in the corresponding dimension restrictions.
Dimensional constraints have the name of the constructor. They can include text size restrictions, restrictions on names or expression. A lock icon appears next to all the dimensional constraints to help distinguish them from normal size. By default, the dimensional constraints are displayed with a fixed system font, which is of the same size on the screen. It is possible to scale. So they are always readable.
Parameter Manager, which is available from the ribbon menu, allows to control both the dimensional parameters and create and manage user-defined parameters. It is possible to assign a sensible name for the parameter and then assign a numeric value or formula as its expression. The expression may refer to other parameters, so that its value is automatically updated when the values of these other parameters are changing.
Looking at such software programs it is possible to say that such school subjects as geometry and algebra are necessary in nowadays technologies.