At present, common positioning technologies mainly include: Bluetooth, RFID, WIFI, Ultra Wide Band (UWB), Ultrasound, etc. The positioning system is a wireless positioning technology that transmits data at high speed over a short distance with very low power.
Ultra-wideband (UWB) wireless positioning technology has become a hotspot and preferred wireless positioning technology in the future due to its low power consumption, high multi-path resistance, high security, low system complexity, and especially the ability to provide very accurate positioning accuracy. .
UWB technology is a kind of wireless technology with a weak transmission power, an amazing transmission rate (up to 1000 Mbps or higher), relatively good penetration capability, sufficient space capacity, and a wireless technology based on extremely narrow pulses, and no carrier. Through these advantages, it has played a very good role in the indoor positioning. In general, the internal positioning of the UWB technology employs a TDOA ranging position determination algorithm, which is a radio communication system that generates, transmits, receives, and processes the extremely narrow pulse signal at a difference in signal arrival time. The ultra-wideband indoor positioning system includes a UWB receiver, a UWB reference tag, and an active UWB tag. The UWB signal transmitted by the UWB receiver is received at the position, and the various noise interferences in the electromagnetic wave transmission process are filtered to obtain a signal containing valid information, and then the central processing unit performs the distance measurement calculation analysis.
Radio Frequency Identification (RFID) technology
It is a technology that uses the principle of electromagnetic induction to wirelessly excite short-range wireless tags to realize information reading. The radio frequency identification distance ranges from a few centimeters to more than ten meters. The typical application of RFID for personnel positioning comes from the extension of the personnel attendance system. Compared with UWB positioning technology, RFID is mainly used for the identification of people in a certain area, and can not be tracked in real time, and there is no standard network system for positioning applications.
Therefore, it is not suitable for inspections of large equipment, confirmation of personnel safety, etc.
The Wi-Fi positioning application adopts the placement of the wireless base station in the area, and comprehensively determines the coordinates of the Wi-Fi device to be located according to the signal characteristics of the Wi-Fi device to be located and the topology structure of the wireless base station. Wi-Fi positioning technology makes it easy to use existing wireless devices for positioning.
However, compared with UWB positioning, Wi-Fi has poor security, high power consumption, and spectrum resources are approaching saturation. Therefore, it is not conducive to long-term carrying and large-scale application of terminal equipment.
Bluetooth is to measure the strength of the signal to set its location. It is a kind of slow energy consumption. It is applied to the wireless transmission technology in close proximity environment. The corresponding Bluetooth LAN access point is placed indoors, and the mode adjustment will be adopted. The network configuration is set to the multi-user connection mode. It is necessary to determine that the Bluetooth LAN access point is always the primary device of the piconet in order to achieve the effect of obtaining the user's location.
The problem with Bluetooth is that the stability of the Bluetooth system can't keep up. It is easy to be disturbed in complex environments, especially the sound, other signals, and the price of Bluetooth devices have always been considered.
Ultrasonic positioning technology
The use of reflective ranging is the most commonly used method for ultrasonic positioning. The system consists of a main range finder and a plurality of electronic tags. The main range finder is generally arranged on the mobile robot body, and each electronic tag is fixed and arranged in a fixed position in the indoor space. The positioning process is as follows: first, the host computer sends the same frequency signal to each electronic tag, and the electronic tag is reflected and transmitted to the main range finder, so that the distance between each electronic tag and the main range finder can be determined, and Positioning coordinates.
In contrast, ultrasonic waves are significantly attenuated during transmission, affecting their effective range of positioning.
Below, it is a visual comparison through a table.
Don't support two-way communication
Up to 300Mt in close range