CAD automation design funtions

CAD automation design funtions

Postby Michael C » Thu Nov 27, 2014 2:56 am

I found the following CAD automation functions helpful from CADD Primer:

Using Macros:

A macro is a set of instructions recorded in a file that can be played back to perform a task. A sequence of instructions can be stored as a macro, which can be run at any time. As a result, using a macro can reduce a complex and lengthy process down to a single click of a mouse button or key.

Many CADD programs provide built-in capabilities to use macros. In these programs, writing a macro is as simple as selecting the “record macro” and “play macro” function from the menu. When the "record macro" function is selected, whatever sequence of commands you enter are recorded in the macro. You can name the macro as you like and play it back when required. In other programs you need to manually write the commands in a separate file that can be run as a macro.

A macro can be written to accomplish almost any CADD task. For example, you can write a macro to display a series of views to make a presentation on the screen. Other examples of using macros include plotting a set of drawings or making similar corrections to a number of drawings. Whenever you find yourself repeating a task, using a macro is the perfect solution.

Note:

A common problem encountered with macros is that they get stuck when they encounter an unexpected condition in a drawing or when they need certain data input not specified in the macro. It requires thorough checking and testing to make them workable; but it is worth the effort if the task is to be repeated often.

CADD Drawing Automation:

It is the dream of a CADD user to have CADD do as much work by itself as possible. Can CADD be used to draw elevations from plans? Can it dimension the drawing automatically? Can it draw a 3D view from plans and elevations? With the help of advanced programming, it is possible to accomplish all of these tasks.

Many software developers have started to focus on the drawing automation aspect of CADD. There are a number of discipline specific (or add-on programs) available, that can help automate drawing work. For example, an architectural CADD program includes a number of features to automatically draw doors, windows, staircases, bathrooms, kitchens, ceiling grids, floor tiles patterns, etc.

To draw a draw a staircase, you don't need to do all the calculations and draw every component of the staircase line by line. You just need to indicate the floor-to-floor height, the width of the staircase, and choose from a number of staircase styles available. CADD automatically calculates how many steps will be required and draws them automatically. It can draw plans, sections, elevations and 3D view of the staircase. If you need to change the floor-to-floor height or the style of the staircase, the drawing can be updated in a few simple steps.

Customizing CADD:

Customizing CADD plays a major role in achieving drawing efficiency. Most CADD programs allow you to customize them to some extent. You can accomplish the following by customizing CADD:

• You can arrange the tool bars on the screen, as you like. You can place your most commonly used tool buttons in such a way that they are easily accessible, and get rid of the ones that you rarely use.

• You can develop command aliases to enter commands quickly, such as “L” for line, “A” for arc, "S" for save, "P" for Plot, etc.

• You can set up the working environment of CADD as per your requirements. You can set up standard sheet sizes, text styles, dimension styles, layers, line styles, pen numbers, fonts, etc., and instantly apply them to a drawing.

• You can customize the commands to work as per your specific needs. With some knowledge of programming, you may be able to add new functions to facilitate your drawing work.

• You can find suitable add-on programs that offer customized solutions. There are dozens of add-on programs available for all popular CADD programs.

Using CADD Database:

CADD allows you to develop a database that can be linked with the drawing objects in the drawing. You can add descriptions of drawing objects (attributes) in the database and link them to diagrams. The attributes can be used to describe characteristics of diagrams, such as size, color, area and price. If you draw a symbol of a chair, it is just lines and arcs in computer memory; the computer does not know what it is. With the help of attributes, you can describe all the properties associated with it.

The computer can link hundreds of attributes to a symbol and keep all the records in a database. The data stored in the form of a database has an advantage that it can be outputted in different formats. The database can be used to prepare reports and to perform analyses. These capabilities are particularly helpful in managing large projects.

The report generated using the database function of CADD is quite different from preparing such a report manually using non-intelligent CADD functions. If you calculate the area of a rectangle and write the area next to it using the text command, it becomes just text in the computer memory. It has no meaning to the computer. When the area is calculated using the database functions, it is directly linked with the drawing. The computer recognizes the attribute as the area of the rectangle and keeps a record of it. If a change is made to the diagram and the area is changed, it is automatically updated in the spreadsheet. It also updates all the values associated with the area in the spreadsheet.

Important Tip:

There are a number of add-on programs available that specialize in database capabilities. There is a specific category of software just for facility management called computer-aided facility management (CAFM) software. These programs are designed to keep records of furniture, equipment, areas, linear units, etc., associated with buildings. Popular CAFM programs include: Archibus, Drawbase and Aperture. (See Chapter 10 for contact information.)

The Design Applications of CADD:

Although CAD is an acronym for computer-aided design and CADD for computer-aided design and drafting most programs do not offer any design capabilities. They are just drafting programs, but manufacturers call them CAD or CADD anyway. You may be able to work out designs using the drafting capabilities of CADD, but that is not real computer-aided design. A CADD program can be truly called a design program only when it has the ability to solve problems and perform analyses.

Design is a vast subject and has different applications for different professionals. It has a specific meaning to an architect, a structural engineer, a civil engineer or a mechanical engineer. An architect may use CADD to design a building part, a structural engineer may use it for a design calculation and a civil engineer may use it for certain site design analysis.

The design applications of CADD are still a subject of research. Many academic institutes offer postgraduate courses dedicated to research and development of CADD design software. Some design programs have been developed for engineering applications, but generally they need to be customized.

Design programs are based on a number of principles and vary significantly in their approach. Some are mainly based on calculations, some involve comparison and logic in the program, while others involve the use of a database or another form of artificial intelligence. The following are some examples of design programs:

• Calculation programs
• Intelligent CAD
• Knowledge-based CAD systems

Calculation Programs:

Calculation programs are extremely effective in solving complex mathematical problems. Specialized engineering CADD programs are designed to compute scientific, trigonometric, logarithmic and exponential functions. They can be used to perform many inter-connected calculations. If one variable in the calculation is changed, the program automatically adjusts the rest of the calculations. For example, a structural engineer working with frame structures does not have to calculate all the members each time a new span or load is added to the structure. The computer program understands that everything else is constant except the load and the span and can give the end results within seconds.

A useful advancement in calculation programs is parametric modeling. Parametric modeling enables the user to link calculations with the geometric drawing. Certain graphic elements and dimensions are linked with the end results of the calculations. The computer automatically adjusts the geometry based on the calculations, or it can be programmed to adjust the calculations based on the geometry. Parametric modeling is commonly used to create computer-generated simulations of machine parts.

References:

• Structural design engineering software: http://www.xfemily.com/index.htm

• Simulation video gallery: http://caad.arch.ethz.ch/main.html

• CAD program for the analysis and design of electromagnetic and thermal devices: http://www.magsoft-flux.com/

Intelligent CAD:

Intelligent CAD programs are based on logic and comparison, and have a number of applications in product design, mechanical design, space planning, etc. These programs are not based purely on mathematics as the calculation programs. Besides mathematics, they analyze forms, shapes, arrangement of objects, patterns, colors, etc. They can draw conclusions even if the resulting statements are not completely true or false (a technique known as Fuzzy-logic).

Intelligent CAD programs make decisions based on hundreds of parameters defined in the program. For example, a road design program can help in developing road layouts based on the road-construction criteria. It can analyze whether a particular road design is appropriate to handle a given traffic. It can analyze the width of the road, turning radius, code violations and other constructibilty issues based on the traffic patterns.

Another example of an intelligent CAD program is space planning. A designer can use a design program to make furniture layouts. The program is designed to control parameters associated with the layout, such as minimum and maximum distance between tables and acceptable orientation of chairs and tables. The program can address hundreds of specified do's and don'ts and prepare design alternatives.
References:

• Automatic review tool for CAD/CAM drawings (road design): http://www.shai.com/projects/auto_review.htm

• Artificial Intelligence in AutoCAD with Lisp (furniture layout):
http://xarch.tu-graz.ac.at/autocad/adge ... 96_AI.html

Knowledge-based CAD Systems:

Knowledge-based CAD systems (also known as expert systems), make use of information gathered from previous projects (or parameters defined by the programmer) and use it for new design proposals. The knowledge-based systems enable large corporations to constantly improve their design and manufacturing process. Let's say an engineering firm specializes in automobile design. They may have designed dozens of automobiles and have encountered hundreds of design problems associated with them. To design a new automobile, they don't need to address all the issues again. They can use the information gathered in the knowledge-based system to find quick solutions.

Knowledge-based systems are capable of addressing thousands of rules defined in the program. They make decisions based on these predefined rules. This process is referred to as rule-based reasoning. An advanced form of this process is called case-based reasoning that allows the user to define a new set of rules case by case.

References:

• Knowledge Technologies International offers a number of knowledge-based solutions for large corporations such as British Aerospace, Boeing, Jaguar and BMW: http://www.ktiworld.com

• CAD Research Center, Polytechnic State University, California has developed a knowledge-based system called ICADS. In contains building design information that can be used by architects to address environmental concerns in buildings: http://www.csc.calpoly.edu/~cadrc/
Integrated Systems
Integrated systems are a group of systems and software that can work in a network environment and share information. This approach is commonly adopted in large corporations that need hundreds of computers networked. The integrated systems are designed to include different application programs in one package. The programs are able to work as independent programs as well as share information.

The significance of an integrated system is that it enables one department to use relevant information produced by another. For example, different departments in a large manufacturing company can use CADD drawing to streamline manufacturing process. The engineering department can use CADD drawing to perform engineering analysis using computer aided engineering (CAE) programs. The manufacturing department can use the CADD the drawing for computer aided manufacturing (CAM). The estimating department can use CADD database to prepare reports and estimates. The managers can use CADD and management software such as electronic document management (EDM) and product data management (PDM) to monitor projects.

Large corporations often develop customized integrated software that meets their needs. They include a number of capabilities from design and drafting to project management. Integrated systems are expensive, but they contribute to a highly productive environment. Some examples of popular integrated systems are: CADRA, CADDS, CATIA-CADAM, MEDUSA, MICROCADAM, I-DEAS, PRO/ENGINEER and Unigraphics. They offer varying degree of integration. See Chapter 10 "CADD Industry Resources" for description and contact information.

Note: 100% integrated systems do not exist.

Collaborating CADD Projects on the Internet:

Internet is changing the way professionals collaborate CADD projects. Professionals can work as team and share CADD drawings with others thousands of miles away. The drawings can be sent using the E-mail and are delivered within minutes. Another method of distributing drawings is FTP. Using the FTP method, you can upload the CADD drawing files to specific server or web site. Any one with access to that server or web site can download the drawings. The E-mail and FTP methods are ideal for distributing drawings, however they do not provide real-time interaction between the team members.

There are a number of project collaboration software available that allow you to share drawings on the web in real-time. Most CADD programs include tools that allow you to export the drawings to a format that can be published on the web. Two common formats available are DWF and SVF. The drawings in these formats can be viewed on the web by using a browser that has special plug-in to display these formats.

Advanced project collaboration software allows you to mark CADD drawings and have virtual meeting with others using a web site. You can create and edit drawings right in front of them and they can provide their feedback right away.

There is a lot of development taking place with respect to CADD technology on the web. Some of the CADD software companies offer the use of CADD and collaboration software right from their web site. You don't need to buy and install the software on your computer. You can rent it and use it directly from their web site.
Michael C
 

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