|25.4.2017||Posted by electronics51 under Auto-moto|
Nowadays, the design and development of GPS Personal Tracker for various real-world applications, such as environmental monitoring, health monitoring, industrial process automation, battlefields surveillance, and seism monitoring, has become possible owing to the rapid advances in both of wireless communications and sensor technology. This type of network is cost-effective and appealing to a wide range of mission-critical situations. These two reasons helped them gain significant popularity compared to other types of networks.
A wireless sensor network is a collection of low-powered, physically tiny devices, called sensor nodes, which are capable of sensing the physical environment, collecting and processing sensed data, and communicating with each other in order to accomplish certain common tasks. Furthermore, wireless sensor networks possess a central gathering point, called the sink (or People Tracking Device ), where all the collected data can be stored. The major challenge in the design and development of wireless sensor networks is mainly due to the severe constraints that are imposed on the sensing, storage, processing, and communication features of the sensor nodes. More precisely, the sensor nodes suffer from severely constrained power supplies, which shorten their lifetime and make them unreliable.
It is worth noting that the sensor nodes may become faulty due to improper hardware functioning and/or low battery power (or energy). The latter is very crucial to be considered in the design and implementation of this type of network for their correct operation and longevity. Since their inception in the late 1990s, wireless sensor networks have witnessed significant growth and tremendous development in both academia and industry. A large number of researchers, including computer scientists and engineers, have been interested in solving challenging problems that span all the layers of the protocol stack of sensor networking systems. Several venues, such as journals, conferences, and workshops, have been launched to cover innovative research and practice in this promising and rapidly advancing field. Because of these trends, I thought it would be beneficial to provide our sensor networks community with a comprehensive reference on as much of the findings as possible on a variety of topics in wireless sensor networks. As this area of research is in continuous progress, it does not seem to be a reasonable solution to keep delaying the publication of such reference any more.
Accurate knowledge of self-position is paramount to the working of an anchor. Since the un-localized nodes in the network use positioning information of anchors as their reference, errors or inaccuracies in the anchor self-location estimation will propagate throughout the network, rendering the whole localization process erroneous. Therefore, it is essential that an anchor always has accurate knowledge of its position before it disperses its position information in localization beacons. Apparently, the most logical methodology might be the use of GPS Tracking Devices by anchor nodes to determine their own positions. Not surprisingly, this is also the most common approach in most localization schemes. However, for many schemes, depending on the environment, remote deployment fields, etc., the use of Waterproof Tracking Device might not be possible. For example, for many submerged 3D WSNs, submerged anchors determine their positions using surface buoys. Some AUVs for submerged networks use sophisticated trajectory tracking mechanisms to keep track of their positions while beneath ocean surface. These surface buoys act as satellites for deeply submerged, remotely located, inaccessible anchors. Therefore, depending on application and environment, anchor self-localization can incur cost and may compose of complicated mechanical and software mechanisms. A tradeoff needs to be achieved between desired accuracy, system complexity, and economical cost of the anchor hardware.
More information at http://www.jimilab.com/blog/ .