Modular design

In systems engineering, modular design — or "modularity in design" — is an approach that subdivides a system into smaller parts (modules) that can be independently created and then used in different systems to drive multiple functionalities. A modular system can be characterized by the following:

"(1) Functional partitioning into discrete scalable, reusable modules consisting of isolated, self-contained functional elements; (2) Rigorous use of well-defined modular interfaces, including object-oriented descriptions of module functionality; (3) Ease of change to achieve technology transparency and, to the extent possible, make use of industry standards for key interfaces."

Besides reduction in cost (due to lesser customization, and less learning time), and flexibility in design, modularity offers other benefits such as augmentation (adding new solution by merely plugging in a new module), and exclusion. Examples of modular systems are cars, computers and high rise buildings. Earlier examples include looms, railroad signaling systems, telephone exchanges, pipe organs and electric power distribution systems. Computers use modularity to overcome changing customer demands and to make the manufacturing process more adaptive to change (see modular programming). Modular design is an attempt to combine the advantages of standardization (high volume normally equals low manufacturing costs) with those of customization. A downside to modularity (and this depends on the extent of modularity) is that modular systems are not optimized for performance. This is usually due to the cost of putting up interfaces between modules.

Proper inter-modular design

Recognizing that excessive inter-module dependencies are an indicator of poor software design, a system should be intended to be loosely coupled to avoid unnecessary dependencies. Thus, inter-modular design should be easy to work with because modules can be easily understood in isolation, and changes or extensions to functionality would be easily localized.

Modular design in cars

Aspects of modular design can be seen in cars or other vehicles to the extent of there being certain parts to the car that can be added or removed without altering the rest of the car.

A simple example of modular design in cars is the fact that, while many cars come as a basic model, paying extra will allow for "snap in" upgrades such as a more powerful engine or seasonal tires; these do not require any change to other units of the car such as the chassis, steering or exhaust systems.

Modular design in buildings

Modular design can be seen in certain buildings, especially modular buildings. Modular buildings generally consist of universal parts (or modules) that are manufactured in a factory and then shipped to a build site where they are assembled into a variety of arrangements.

Modular buildings can be added to or reduced in size by adding or removing certain components. This can be done without altering larger portions of the building. Modular buildings can also undergo changes in functionality using the same process of adding or removing modular components.

For example, an office building can be built using modular parts such as walls, frames, doors, and windows. The office interior can then be partitioned (or divided) with more walls and furnished with desks, computers, and whatever else is needed for a functioning workspace. If the office needs to be expanded or redivided to accomodate employees, modular components such as wall panels can be added or relocated to make the necessary changes without altering the whole building. Later on, this same office can be broken down and rearranged to form a retail space, conference hall or any other possible type of building using the same modular components that originally formed the office building. The new building can then be refurnished with whatever items are needed to carry out its desired functions.

See also

• Holism
• Modular Function Deployment
• Modular programming
• Separation of concerns

Further reading

• Erixon, O.G. and Ericsson, A., "Controlling Design Variants" USA: Society of Manufacturing Engineers 1999[1] ISBN 0-87263-514-7 [2]
• Clark, K.B. and Baldwin, C.Y., "Design Rules. Vol. 1: The Power of Modularity" Cambridge, Massachusetts: MIT Press 2000 ISBN 0-262-02466-7
• Baldwin, C.Y., Clark, K.B., "The Option Value of Modularity in Design" Harvard Business School, 2002 [3]
• Modularity in Design Formal Modeling & Automated Analysis
• "Modularity: upgrading to the next generation design architecture", an interview