Cognition & Design

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Redundancy is a design principle whereby elements are used more than necessary to prevent system failure, to increase the performance or maximize the functionality. There are four types of redundancy being used ; which are diverse redundancy , homogeneous redundancy, active redundancy and passive redundancy .

Diverse redundancy is the use of multiple elements of different types to perform the same function (for example, the use of text, audio and video to communicate the same information).

Figure 1.0 . Three side buttons of Lumia model.

Figure 1.0 shows three side buttons of a Lumia model which represents the volume button ( left most ) , the power button and the camera button . As we all know, taking picture using smartphone can be as simple as clicking the camera icon when the camera application is open or simply by clicking on the phone screen. However, some phone model , like the Lumia shown , provide the user with a camera button at the side of the phone which user can use to snap a picture or two.

Homogeneous redundancy is the use of multiple elements of the same type . This type of redundancy is one the most common redundancy type whereby multiple elements are provided or exist in a product or design. All the elements are of the same type and perform the same function and it is up to the user on how much they want to make use of the available elements.

Figure 2.0 USB Ports

Figure 2.0 shows the USB ports of a laptop. As we can see, there are three USB ports provided by the manufacturer for the user to use. This USB ports are all of the same designs and types.

Active redundancy is the use of redundant elements at all times that can help to guard against failure of individual elements and also of the whole system. This type of redundancy can be seen when multiple elements are presents and they all carry certain functions without which would cause problems to the functionality or performance of the product or system.

An example of active redundancy is as shown in figure 3.0 which is the curtain hooks. There are quite number of hooks that we use when we hang a curtain. Each hook performs its functions of making sure the curtain can be hung and look firm. However, when one or two hook fail to function or the hook comes off the curtain does not fall down.

Passive redundancy is the presence of redundant elements which is only used during cases of failure, such as having a spare car tyre, a spare laptop or disc drive to a presentation. This is one of the most common type of redundancy. This spare or contingency element present when another primary element of the same function fail to function or when the use of it is less efficient.

Figure 4.0

Figure 4.1

Figure 4.0 and 4.1 shows the fireman intercommunication system which can be open by using its respective keys. However, in case of emergency or failure to use the keys , another option is available for the user to open it by breaking the glass. No one would break the glass if they have the key with them. This serves as a passive contingency whereby it is only use in cases of failure or emergency.

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Figure 8.4.1 : Mechanical pencil