Centimeter-level ultra-wideband positioning uwb development board achieves indoor positioning to reduce errors. How does UWB positioning system achieve indoor positioning? Principle analysis!
I. What is the UWB positioning system?
UWB, it's Ultra Wideband, ultra broadband technology. It stems from the rise of pulse communication technology in the 1960s. Different from traditional communication technology, UWB realizes wireless transmission by sending and receiving extremely narrow pulses below nanosecond or microsecond level, so it has a wide spectrum range and high time resolution.
Indoor positioning system is based on centimeter-level ultra wideband positioning uwb development board. The indoor positioning system application software supports PC and mobile terminal access, and is mainly used in tunnel, prison, chemical industry, factory, coal mine, construction site, power plant, pension, exhibition hall, vehicle, computer room, airport and other industries.
Two, UWB positioning system principle
The cm-level uwb positioning system is composed of application layer, service layer, transport layer and perception layer (positioning base station and positioning label). The main network communication mode of the transport layer is wired or wireless communication.
Perceptive layer
The sensing layer mainly includes location base station and location tag. Base station and tag are the core equipment of positioning system. Centimeter-level uwb locating UWB development board tags will broadcast radio signals with their own ID number at intervals. After receiving the signal sent by the label, the base station transmits the time stamp and label ID card number of the received signal to the service layer through the main network to complete the location of the label card. The base station can also receive instructions sent from the application layer to complete the relevant Settings.
Transport layer
The transport layer, also known as the main communication network (hereinafter referred to as the "main network"), is the data transmission channel between the base station, the service layer and the application layer. The relevant instructions of the application layer are transmitted down to the base station of the uwb development board at the centimeter level, and the original positioning data (the distance between the label and the base station) is transmitted up to the service layer, and the data is transmitted through the wired optical fiber.
Service layer
The tag coordinates are measured by the tag and the positioning base station in the covering area, and the tag coordinates are solved by TDOA algorithm or TOA algorithm. In addition, the service layer provides flexible device management and network management functions, as well as a variety of front-end functions and application interfaces.
Application layer
Obtain the specific location of the location tag through the service layer, display the location of the tag in real time in the form of one-dimensional, two-dimensional or three-dimensional map, and provide track playback, personnel information management and call rescue functions.
In addition, the application layer also provides websocket interfaces and http interfaces. The real-time location data of the tag card can be obtained through websocket interface, and the data related to the system of the centimeter-level ultra-wideband positioning uwb development board can be obtained through http interface. Therefore, the positioning system is easy to be developed and integrated.
Three, UWB positioning system hardware support
Indoor positioning base station and positioning label are the hardware components of UWB positioning system. Locate the base station distributed on the geometric edge of the site scenic spot, and cover the signal of the area. The main function of indoor positioning base station is to detect the label data information and upload it to the server for summary and analysis. Centimeter-level ultra wideband positioning uwb development board positioning tags are attached to the surface of the positioning object. When the tag enters the base station's signal coverage, it automatically establishes contact with the base station. Positioning labels can be attached in different ways, such as hanging and pasting, according to application requirements. The size and shape of positioning labels vary according to different objects.
4. Advantages of UWB positioning system
1. High precision
In the field of indoor positioning, UWB positioning is the only technology to achieve centimeter-high precision positioning. Cm-level ultra-wideband positioning UWB development board uses TDOA (arrival time) algorithm to measure the time of electromagnetic wave from the transmitting end to the receiving end. Several receiving ends distributed in the room receive electromagnetic wave signals from the transmitting end at the same time, and accurately calculate the position of the transmitting end in the room according to the transmission speed of electromagnetic wave, with positioning accuracy up to 10cm. Basically meet the needs of most indoor positioning scenarios for high precision positioning!
2. Extensible
UWB positioning system can not only provide positioning function, but also expand the historical track playback, personnel attendance, electronic fence, behavior analysis, intelligent inspection and other comprehensive positioning service functions. These service functions based on location data can help managers to carry out security management of enterprises, which can effectively reduce the occurrence of security accidents.
3. Low power consumption
Cm-level ultra-wideband positioning uwb development board wireless communication system receiver without local vibration, power amplifier, lock ring (PLL), voltage controlled oscillator (VCO), mixer, etc. Therefore, the structure is simple and the equipment cost will be very low. Because UWB signals do not require a carrier, but send data using intermittent pulses, which are of very short duration, generally between 0.20 and 1.5ns, and have a very low duty factor, it requires only very low power supply. Generally, UWB positioning system only requires 5 ~ 7mW power supply, which is one-tenth of Bluetooth technology.
Why does centimeter-level ultra-wideband positioning uwb development board positioning system exist positioning errors? With the development of the Internet of Things era, indoor positioning has become an indispensable and important application in daily life, and positioning technology has gradually become the basic core technology of various new scenarios. UWB positioning system has become an important part of the indoor positioning industry because of its unique advantages such as high positioning accuracy, low power consumption, strong anti-interference ability and strong permeability.
I. Main sources of error of UWB positioning system
1. Clock synchronization accuracy
The TOA positioning algorithm requires accurate time synchronization between the target node and the reference node, and the TDOA positioning algorithm of the cm-level uwb development board requires accurate clock synchronization between the reference nodes. Therefore, inaccurate time synchronization may lead to positioning errors in the UWB system. However, due to hardware limitations, it is not possible to synchronize the clock with complete accuracy.
2. Multipath propagation
In the TOA estimation algorithm, the time when the matched filter outputs a large value or a relative large value is usually used as the estimate. Due to the existence of multipath, the position of correlation peak is shifted, so there is a large error between the estimated value and the actual value.
3. Non-line-of-sight propagation
Line-of-sight propagation is a necessary condition for obtaining accurate measurement of signal characteristics. When there is no direct propagation path between two points, only the signal reflection and derived components can reach the receiving end. At this time, the arrival time of the first pulse cannot represent the true value of TOA, and there is non-line-of-sight error.
4. Multiple access interference
In a multi-user environment, signals from other users can interfere with the target signal, thus reducing the accuracy of the estimate. One way to reduce this interference with centimeter-level ultra-wideband positioning uwb development boards is to separate signals from different users in time, i.e. using different gaps to transmit different nodes.
Ii. How to accurately position the UWB positioning system?
The UWB positioning system uses broadband narrow pulse communication technology (high time resolution, reduce positioning error), multi-source data integration (effectively improve the anti-interference ability of the positioning system) and time series signal processing technology (extract the first path signal in the strong multi-path complex environment) to achieve accurate positioning of the positioning target.
At the same time, the use of wireless synchronization method, is also the industry has centimeter level ultra wideband positioning uwb development board UWB wireless synchronization technology manufacturers. Wireless synchronization means that each base station realizes and maintains overall time coordination by constantly exchanging team clock information with other base stations. Wireless synchronization depends on the measurement time accuracy of UWB. The higher the time accuracy, the smaller the time error between the two base stations, the higher the degree of time synchronization. The advantage of wireless synchronization is that there is no need for wired connections between base stations, so it is easy to deploy and low cost.
