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An indoor positioning system (IPS) is a system to locate objects or people inside a building using radio waves, magnetic fields, acoustic signals, or other sensory information collected by mobile devices.〔Kevin Curran, Eoghan Furey, Tom Lunney, Jose Santos, Derek Woods and Aiden Mc Caughey (2011) An Evaluation of Indoor Location Determination Technologies. Journal of Location Based Services Vol. 5, No. 2, pp: 61-78, June 2011, ISSN: 1748-9725, DOI:10.1080/17489725.2011.562927, Taylor & Francis〕 There are several commercial systems on the market, but there is no standard for an IPS system. IPS systems use different technologies, including distance measurement to nearby anchor nodes (nodes with known positions, e.g., WiFi access points), magnetic positioning, dead reckoning. They either actively locate mobile devices and tags or provide ambient location or environmental context for devices to get sensed.〔Eoghan Furey, Kevin Curran and Paul Mc Kevitt (2012) ''HABITS: A Bayesian Filter Approach to Indoor Tracking and Location. International Journal of Bio-Inspired Computation'' (IJBIC) Vol. 4, No. 2, pp: 79-88, ISSN: 1758-0366, DOI: 10.1504/IJBIC.2012.047178, InderScience 〕 The localized nature of an IPS has resulted in design fragmentation, with systems making use of various optical,〔Liu X, Makino H, Mase K. 2010. Improved indoor location estimation using fluorescent light communication system with a nine-channel receiver. IEICE Transactions on Communications E93-B(11):2936-44.〕 radio,〔Chang N, Rashidzadeh R, Ahmadi M. 2010. Robust indoor positioning using differential Wi-Fi access points. IEEE Transactions on Consumer Electronics 56(3):1860-7.〕〔Chiou Y, Wang C, Yeh S. 2010. An adaptive location estimator using tracking algorithms for indoor WLANs. Wireless Networks 16(7):1987-2012.〕〔Lim H, Kung L, Hou JC, Luo Haiyun. 2010. Zero-configuration indoor localization over IEEE 802.11 wireless infrastructure. Wireless Networks 16(2):405-20.〕〔Reza AW, Geok TK. 2009. Investigation of indoor location sensing via RFID reader network utilizing grid covering algorithm. Wireless Personal Communications 49(1):67-80.〕〔Zhou Y, Law CL, Guan YL, Chin F. 2011. Indoor elliptical localization based on asynchronous UWB range measurement. IEEE Transactions on Instrumentation and Measurement 60(1):248-57〕 or even acoustic〔Schweinzer H, Kaniak G. 2010. Ultrasonic device localization and its potential for wireless sensor network security. Control Engineering Practice 18(8):852-62.〕 technologies. System designs must take into account that at least three independent measurements are needed to unambiguously find a location (see trilateration). For smoothing to compensate for stochastic (unpredictable) errors there must be a sound method for reducing the error budget significantly. The system might include information from other systems to cope for physical ambiguity and to enable error compensation. == Applicability and precision == Due to the signal attenuation caused by construction materials, the satellite based Global Positioning System (GPS) loses significant power indoors affecting the required coverage for receivers by at least four satellites. In addition, the multiple reflections at surfaces cause multi-path propagation serving for uncontrollable errors. These very same effects are degrading all known solutions for indoor locating which uses electromagnetic waves from indoor transmitters to indoor receivers. A bundle of physical and mathematical methods is applied to compensate for these problems. Promising direction radiofrequency positioning error correction opened by the use of alternative sources of navigational information, such as inertial measurement unit (IMU), monocular camera Simultaneous localization and mapping (SLAM) and WiFi SLAM. Integration of data from various navigation systems with different physical principles can increase the accuracy and robustness of the overall solution.〔Vladimir Maximov and Oleg Tabarovsky, LLC RTLS, Moscow, Russia (2013). Survey of Accuracy Improvement Approaches for Tightly Coupled ToA/IMU Personal Indoor Navigation System. Proceedings of International Conference on Indoor Positioning and Indoor Navigation, October 2013, Montbeliard, France.(See publication here )〕 With detailed reading in the marketing documents and even in the specifications served by many of the IPS vendors, the interested customer will look for details on precision, reproducibility and other terms for quality of function with little success. Many vendors do not even tangle with the term ''accuracy'' 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「indoor positioning system」の詳細全文を読む スポンサード リンク
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