Home Automation And Consumer Electronics

Published Date: 02 Nov 2017

A large, industrial facility typically has a relatively small control room, surrounded by a relatively large physical plant. The control room will have indicators and displays that describe the state of the plant like the state of valves , the condition of equipment , the temperature and pressure of stored materials. As well as input devices that control actuators in the physical plant(valves, heater,etc.) that effect the observed state of the plant. The sensors describing the state of the physical plant, their displays in the control room, the control input device and the actuators in the plant are often all relatively inexpensive when compared with the cost of the armored cable that must be used to communicate between them in a wired installation. Significant cost savings may be achieved if an inexpensive wireless means were available to provide this communication. Because the information being communicated is the state information, if often changes slowly. Thus, in the normal operation , the required data throughput of the network is relatively low, but the required reliability of the network is very high. A wireless sensor network of many nodes , providing multiple message routing paths of multi-hop communication, can meet these requirements.

An example of wireless industrial control is the control of commercial lighting. Much of expense in the installation of lights in a large building concerns the control of light – where the wired switches will be , which lights will be turned on and off together, dimming of the lights,etc. A flexible wireless system can employ a handheld controller that can be programmed to control a large number of lights in a nearly infinite variety of ways, while still providing the security needed by a commercial installation.

A further example is the use of wireless sensor networks for industrial safety applications. Wireless sensor networks may employ sensors to detect the presence of noxious, poisonous , or otherwise dangerous materials, providing early detection and identification of leaks or spills of chemicals or biologically agents before serious damage can result (and before the material can reach the public).Because the wireless networks may employ distributed routing algorithms, have multiple routing paths, and can be self healing and self-maintaining, they can be resilient in the face of an explosion or other damage to the industrial plant, providing officials with the critical plant status information under very difficult conditions.

The monitoring and control of rotating or otherwise moving machinery is another area suitable for wireless sensor area networks. In such applications, wired sensor and actuators are often impractical, yet it may be important to monitor the temperature, vibration , lubrication flow, etc. of the rotating components of the machine to optimize the time between maintenance periods, when the machine must be taken off-line. To do this, it is important that the wireless sensor system be capable of operating for the full interval between maintenance periods; to do otherwise defeats the purpose of the sensors. This, in turn, requires the use of a wireless sensor network with very low energy requirements. The sensor node often must be physically small and inexpensive as well. Wireless sensor networks may be of particular use in the prediction of component failure for aircraft, where these attributes may be used to particular advantage.

Still another application in this area for wireless sensor networks is the heating, ventilating, air conditioning (HVAC) of buildings. HVAC systems are typically controlled by a small number of strategically located thermostat and humidistat. The number of these thermostats and humidistats is limited, however, by the costs associated with their wired connection to the rest of the HVAC system. In addition, the air handlers and dampers that directly control the room environment are also wired; for the same reasons, their numbers are also limited.

Such a wireless HVAC system has other advantages. Close monitoring of system performance enables problems to be identified and corrected before occupant complaints arise. In addition to the living-area sensors, wireless sensors may be placed inside air ducts (to monitor the performance of heat exchange apparatus, for example) without requiring maintenance personnel to make manual measurements atop ladders. In addition, sensors may be placed in attics and crawlspaces that contain ductworks; anomalous temperatures in such areas may indicate costly leaks of heated or cooled air. For these reasons, total building HVAC costs should drop, while occupant comfort would increase when wireless sensors and actuators are employed.

1.1.2 Home automation and consumer electronics

the home is very large application space for wireless sensor networks. Many of the industrial applications just described have parallels in the home. For example, a home HVAC system equipped with wireless thermostats and dampers can keep the rooms on the sunny side of the house comfortable-without chilling the occupants on the shady side of the house-more effectively than a home equipped with only a single, wired thermostat. However, many other opportunities are available.

One application is the "universal" remote control, a personal digital assistant (PDA)-type device that can control not only the television, DVD player, stereo, and other home electronic equipment, but the lights, curtains, and locks that are also equipped with a wireless sensor network connection. With the universal remote control, one may control the house from the comfort of one’s armchair. Its most intriguing potential, however, comes from the combination of multiple services, such as having the curtains close automatically when the television is turned on, or perhaps automatically muting the home entertainment system when a call is received on the telephone or the doorbell rings. With the scale and personal computer both connected via a wireless sensor network, one’s weight may be automatically recorded without the need for manual intervention ( and the possibility of stretching the truth "just this once").

A major use of wireless sensor networks in the home is expected to be for personal computer peripherals, such as wireless keyboard and mice. Such applications take advantage of the low cost and low power consumption that are the sine qua non of wireless sensor networks. Another application in the home is sensor-based information appliances that transparently interact and work symbiotically together as well as with the home occupant.

Toys represent another large market for wireless sensor networks. The list of toys that can be enhanced or enabled by wireless sensor networks is limited only by one’s imagination, and range from conventional radio-controlled cars and boats to computer games employing wireless joysticks and controllers. A particularly intriguing field is personal computer (PC)- enhanced toys , which employ the computing power of a nearby computer to enrich the behavior of the toy itself. For example, speech recognition and synthesis may be performed by placing the microphone and speaker in the toy, along with the appropriate analog-to-digital and digital-to-analog converters, but employing a wireless connection to the computer, which performs the recognition and synthesis functions. By not placing the relatively expensive yet limited speech recognition and synthesis circuits in the toy, and using the (much more powerful) computing power already present in the computer, the cost of the toy may be significantly reduced, while greatly improving the capabilities and performance of the toy. It is also possible to give the toy complex behavior that is not practical to implement in other technologies.

Another major home application is an extension of the key Remote Keyless Entry (RKE) feature found on many automobiles. With wireless sensor networks, wireless locks, door and window sensor, and wireless light controls, the homeowner may have a device similar to a key job with a button. When this button is pressed, the device locks all the doors and windows in the home, turns off most indoor lights (save a few night lights),turns on outdoor security light, and sets the home’s HVAC system to nighttime(sleeping) mode. The user receives a reassuring "beep" once this is all done successfully, and sleeps soundly, knowing that the home is secure. Should a door be left open, or some other problem exists, a small display on the device indicates the source of the trouble. The network may even employ full home security system to detect a broken window or other trouble.

Outside of the home, the location-aware capabilities of wireless sensor networks are suitable for a diverse collection of consumer-related activities, including tourism and shopping. In these applications, location can be used to provide context-specific information to the consumer. In the case of the tourism guide, the user is provided only information relevant to his present view; in the case of the shopping guide, the user is provided information relevant to the products before him, including sale items and special discount and offers.

1.1.3 Security and military sensing

the wireless security system described above for the home can be augmented for use in industrial security applications. Such systems, employing proprietary communication protocols, have existed for several years. They can support multiple sensors relevant to industrial security, including passive infrared, magnetic door opening, smoke, and broken glass sensors, and sensors for direct human intervention (the " panic button" sensor requesting immediate assistance).

As with many technologies, some of the ealiest proposed uses of wireless sensor networks were for military applications. One of the great benefits of using wireless sensor networks is that they can be used to replace guards and sentries around defensive perimeters, keeping soldiers out of harm’s way. In this way, they can serve the same function as antipersonnel mines, without the attendant hazard mines represent to allied personnel during the battle (or the civilian population afterward ). In addition to such defensive applications, deployed wireless sensor networks can be used to locate and identify targets for potential attack, ant to support the attack by locating friendly troops and unmanned vehicles. They may be equipped with acoustic microphones, seismic vibration sensors, magnetic sensors, ultra wideband radar, and other sensors.

Wireless sensor networks can be small, unobtrusive, and camouflaged to resemble native rock, trees, or even roadside litter. By their nature, multi hop networks are redundant. These networks have distributed control and routing algorithms (i.e.,without a single point of failure), a feature that makes them difficult to destroy in battle. The use of spread spectrum techniques, combined with the bursty transmission format common to many wireless sensor networks (to optimize battery life), can give them a low probability of detection by electronic means. The relative location determination capability of many ad hoc wireless sensor networks can enable the network nodes to be used as elements of a retro directive array of randomly distributed radiating elements; such an array can be used to provide exfiltration of the sensor network data. The relative location information is used to align the relative carrier phase of the signals transmitted by each node; with this information, the exhilarated data may be transmitted not just in the direction of the incoming signal, but in any desired direction. Beam forming techniques can also be applied to the sensors themselves, to enhance their sensitivity and improve detection probabilities.

Wireless sensor networks can also be effective in the monitoring and control of monitoring populations with the use of optical, audio, chemical, biological, radiological sensors to track individuals and groups. The control of wireless sensor networks and the data they produce in a free society, while an important public policy discussion, is outside the scope of this text.

1.1.4 Asset tracking and supply chain management

A very large unit volume application of wireless sensor networks is expected to be asset tracking and supply chain management.

Asset tracking can take many forms. One example is the tracking of shipping containers in a large port. Such port facilities may have tens of thousands of containers, some of which are empty and in storage, while others are bound for many different destinations. The containers are stacked, both on land and on ship. An important factor in the shipper’s productivity (and profitability) is how efficiently the containers can be organized so that they can be handled the fewest number of times and with the fewest errors. For example, it is important that the containers next needed be on top of a nearby stack instead of at the bottom of a stack 1km away. An error in the location record of any container can be disastrous ; a "lost" container can be found only by an exhaustive search of a very large facility. Wireless sensor networks can be used to advantage in such a situation; by placing sensors on each container, its location can always be determined.

Similar situations involving large numbers of items that must be tracked occur in rail yards, where thousands of railroads cars of all types must be organized, and in the manufacture of durable goods, such as cars and trucks, that may sit in large lots or warehouses after manufacture, but before delivery to a retailer.