A wearable computer is a computing device small and light enough to be worn on one’s body without causing discomfort. Unlike a laptop, wearable computer is constantly turned on and interacts with the real-world task.
Wearable computers are computers that are worn on the body. This type of wearable technology has been used in behavioral modeling, health monitoring systems , information technologies and media development. Wearable computers are especially useful for applications that require computational support while the user’s hands, voice , eyes, arms or attention are actively engaged with the physical environment.
A typical wearable computer consists of a battery or human powered computing unit and carried on a belt or in a jacket. The display would be with a head mounted unit. Typically, the input is either voice driven or with wireless wrist mounted devices. The data storage is local and does not depend on any network connection.
Software, being a new dimension in the world of computers demands a phase shift in the human interaction mechanisms. Let us start our detailed discussion of the wearable computer, with this new implementation of computer & human interaction. The traditional desktop metaphors of command line interface or windows- interface are indeed not at all suitable for wearable computing. These interfaces require a constant user concentration & interaction while performing any task, which is not affordable computer. The user’s hands simply may not be free, or the environmental conditions may prevent a good audio input at the time. 
- How does a Wearable Computer look?
A typical wearable computer will have a motherboard worn inside a fashion garment, connecting all the components of the system. The components will be placed at different parts of the body as per the user convenience; power pack and storage in shoes, display and mic on the glasses and keyboard input on the wrist. User input to the computer is either mostly voice driven or sensed from gestures or body motion. The display and audio output generated by the computer will be relevant to be context and environment. The below pictures will give you a better idea of how a wearable computer would look like, the component details and the finished personal garment. 
- Operational modes of wearable computer
There are three operational modes in this new interaction between human and computer:
The computer runs continuously, and is “always ready” to interact with the user. Unlike a hand-held device, laptop computer, or PDA, it does not need to be opened up and turned on prior to use. The signal flow from human to computer, and computer to human depicted in fig. runs continuously to provide a constant user—interface.
Traditional computing paradigms are based on the notion that computing is the primary task. Wearable computing, however, is based on the notion that computing is NOT the primary task. The assumption of wearable computing is that the user will be doing something else at the same time as doing the computing. Thus the computer should serve to augment the intellect, or augment the senses. The signal flow between human and computer is depicted in fig. 
Unlike hand held devices, laptop computers, and PDAs, the wearable computer can encapsulate us It doesn’t necessarily need to completely enclose us, but the concept allows for a greater degree of encapsulation than traditional portable computers.
- Types of wearable computers:
Let’s have a look at some of the wearable computers available or under development.
4.1 Smart shirt
The ‘smart shirt’, a product of Georgia Tech Research Corporation, is a T-shirt that functions like a computer, with optical and conductive fibers integrated into the garment.
It quietly monitors the wearer’s heart rate, respiration, temperature and a host of vital functions, alerting the wearer or physician if there is a problem. The smart shirt also can be used to monitor the vital signs of law enforcement officers, firemen, astronauts, military personnel, chronically ill patients, elderly persons.
4.2 Smart Suit:
The suit, designed at Tampere University of Technology, consists of two-piece underwear supporting vest and actual snow mobile bile jacket and trousers. It can give information about the wearer’s health, location and movements with the help of several integrated sensors. If the wearer has an accident or is in any abnormal situation, the suit will inform an emergency office in the form of a message. The message contains the current coordinates of the user’s position and data from physiological measurements. A Global positioning system (GPS) is employed to acquire the current coordinates.
Heat can be transferred through conducting fibers to colder areas of the body. Cooling also can be automatically handled. The sensoring system consists of a heart rate sensor, three position and movement sensors, ten temperature sensors, an electric conductivity sensor and two defect detecting sensors. In addition to these, there is a user interface (UI), a central processing unit (CPU) and power source.
4.3 Health-monitoring shirt:
The Life Shirt system developed by Vivo Metrics is a typical lifesaver as it collects pulmonary, cardiac and other physiological data and co-relates these over a period of time.
The life Shirt system gathers data during the subject’s daily routines, providing pharmaceutical and academic researchers a continuous ‘movie’ of the subject’s health in real-life situations (i.e. at work, at school, while exercising, or sleeping, etc), rather than the ‘snapshot’ generated during a typical clinic visit.
It acts as a health monitor, communication system, just-in-time information system and an application that controls real-world applications.
4.4 Wearable armband
A sensor device capable of collecting and storing physiological in formation such as the user’s kinetic data, heat flow, skin temperature, ambient temperature and galvanic skin response. The device, called Sense Wear, is worn on the back of the upper arm and stores data continuously for up two weeks.
4.5 No – contact jacket
The no contact jacket’ is a wearable defensive jacket created to aid women in their struggle for protection from violence. When activated by the wearer, 80,000 volts of low amperage electric current flows just below the surface shell of the entire jacket. This electric arm our prevents any person from making unauthorized contact with the wearer’s body. Powered by a regular 9-volt battery, the no contact jacket is fully insulated, so that the wearer does not feel a thing. Even when it is not in use, it jacket is fully insulated,
So that the wearer does not feel a thing. Even when it is not in use, it crackles with tiny, visible electrical arcs that send out messages.
- Hardware Overview:
The wearable computing system is a combination of low power and small-package modules, connected to and controlled by a an embedded microcontroller with its own operating system
As shown in Figure 2, the microcontroller controls all modules. The power management and the serial communication components are realized on an adaptor, which interacts with the microcontroller. The combined GPRS/GPS module  with high sensitivity provides a low-cost communication with server, where the internet is used as the platform. The GPS receiver allows positioning to a precision of 2.5 meters by using a Satellite-Based Augmentation System (SBAS) – in Europe the European Geostationary Navigation Overlay Service (EGNOS).Every wearable computing system that is online can exchange data with the server. In addition, a UHF-RFID module  has been connected just like the GPRS/GPS module to identify RFID labels inside the car. To save energy the microcontroller is able to toggle the power supply of the RFID. A loudspeaker is needed for feedback to recover vehicles using the wearable computing system. 
- Designing the full emergency response wearable system:
In order to fulfill the additional requirements for robustness and user interface, the full system will be based on additional hardware and software. The system uses a wearable CPU core, the so-called qbic belt-worn computer (see Figure 3 (a)).
It is based on an ARM CPU running the Linux operating system, has a bluetooth interface, and can be extended via USB and RS232 interfaces. The wearable CPU core runs the main application program. For localization, the same mobile GPS receiver as in the test system is used, but can be replaced by a non-bluetooth serial device for increased reliability. For communication, the system can use multiple communication channels and already used GSM cell phone can be one of those. 
As already stated, the design of the user interface is a crucial one for this application. Therefore, we vision a user input device integrated in the clothing of the user, e.g., an arm mounted textile keyboard and a wireless link of the keyboard to the belt computer. The second output device is a head mounted display that can be integrated into existing emergency response gear such as firefighter helmets and masks (see Figure 3(b)). In applications where headgear is not commonly used, the output can also be provided through a body-worn display device. The application software driving the user interface is based on the so-called WUI toolkit, which uses an abstract description to define user interface semantics independent of the input and output devices used. The application code is therefore independent of the devices available in a particular instance of an implementation, i.e., with or without head mounted display. The WUI toolkit can also take context information into account, such as the user’s current situation, in order to decide on which device and in what form output and input are provided. 
Figure 3: The qbic belt-worn computer: (a) The belt with CPU. (b) The head-mounted display. (c) Both worn by the test person. 
We need to discuss two different kinds of networks in reference to a wearable computer. One is to connect the device to the external world and the other is to interconnect the various components, the later one being new for wearable computers.
The first issue of connecting to the WC to the external would has several choices; WAP or Cellular Digital packet data This aspect of networking is not specific for a wearable computer, and can evolve over time, from other electronic gadgets.
The second issue of interconnecting the various parts of the WC may involve both wired and wireless connections. CPU, storage unit and similar peripherals will be connected with or without cables to the wearable motherboard, which is a a garment with (physically) flexible bus and standard expansion slots. Peripherals like HMD and wrist/finger worn devices may use standard wireless connections like Bluetooth.
- Wearable Computer Benefits
There are a variety of tasks within the warehouse that require the operator’s full attention — shipping or receiving parcels, performing put-away, picking carton to pallet, and picking to pack. A Wi-Fi-enabled wearable computer leaves operators’ hands free to do the job while still enabling him or her to scan bar codes, enter data or receive instructions in real time.
For bar code reading, wearable’s can be equipped with light-weight, slim ring scanners. Ring scanners make scanning a simple point-and-press operation. Where symbol orientation or placement makes aligning the reader to the symbol difficult or undesirable, a 2D imager puts everything in the right perspective. Imagers make reading both linear and 2D symbols a snap and are required for reading matrix symbols that are becoming more prevalent in some item-marking applications.
Admittedly, not every operation is as simple as scanning a bar code. The display must be able to provide operators with directions, validate entries, or perform a wide range of other tasks. A bright, easy-to-read display is critical. Displays that can be seen from any angle — that is, don’t have to be viewed straight-on — make it easy for operators to view and respond to screen prompts. Ease of viewing make its use more intuitive, less tiring, and less time consuming.
A touch screen can further simplify tasks by offering larger, colorful, and easy-to-see “Buttons” (such as “Yes” and “No”) and provide custom input or response screens for every task or even every step in a task. Screens can be customized to the task rather than the task being customized to available keyboard options. Some wearable computers are also voice-enabled or voice ready to provide new efficiencies or prepare you for future technologies. Voice directed operations and the option to have voice-over-IP (VoIP) and push-to-talk (PTT) at an operator’s fingertips can make a big difference.
- Applications of Wearable computers:
Wearable computers used in many of the applications.
1) Medical Applications
2) Mining Engineering
3) Disability gadget
4) Defence System
6) Marine Engineering
7) High speed quality assurance processes.
- Advantages of Wearable Computing
- Enhanced Communication
- Wearable Computers can be used to recognize a person in a high alerted area such as an airport.
- A personal Wearable will facilitate the wearer’s needs
- Unlikely to be dropped or lost as there are embedded to the clothes as opposed to the handheld devices.
- Able to use wearable computers to complete daily tasks such as a computer which tracks the movements and habits of a person.
- Work from anywhere 
There are many disadvantages of using Wearable Computing. Below are a list compiled by the author of this post.
1) Equipment can be heavy.
3) Some Wearable Computers can consist of allot of wiring.
4) Can cause irritation in heat.
5) Side-Effects such as Headaches.
6) Wearable Computers can invade privacy.
7) Can be used to gain an unfair advantage over others such as Casinos.
8) Being tracked wherever you go.
We have all the technologies needed to make a viable wearable computer today. Lot of research and experiments for practical & commercial use of WC are going on around the world. Several varieties of WCs are indeed commercially available, but as of now most of them are tailor made for specific applications The paradigm shift that the WC will bring; computer working along with you instead of you working at the computer, will have similar impact to the paradigm shift brought by the earlier PCs. It will augment the user’s senses, intellect, memory and provide him with huge amount of computation power and information (both local and networked), without interfering from what he doing. Unlike Artificial Intelligence (attempts to emulate human intelligence in the computer), WCs works alongside the human, both doing what each is better at. After a few cycles of evolution, the wearable computer will become highly ergonomic and a user, over an extended period of usage, will feel it as a true extension of mind and body. And some day there could be Microsoft software in every ones clothing like Microsoft software in every desktop! This will undoubtedly enhance the quality of life of the user, at work place and in all facets of daily life.
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