The indoor positioning system allows managers to pinpoint the location of people or assets accurately, inside a building by using smartphone, Bluetooth beacons, tracking tags, gateways or other IoT devices. It is one of the basic applications of the Internet of Things. When satellite positioning is difficult to be used in complex indoor environments such as tunnels and basements, an indoor positioning system can be used as an auxiliary positioning of satellite positioning to locate the current location of objects and solve the problem that satellite signals cannot penetrate buildings. Based on the application scenario, the satellite positioning system can facilitate the operation of enterprises and provide users with a more satisfactory experience. The purpose of this article is to give you a preliminary understanding of indoor positioning techniques.
The system works as the outdoor GPS to provide positioning services. The difference is that GPS can only be used outdoors and it has no signal when comes into indoor space. So indoor positioning came into being to solve people’s indoor space positioning services. At present, indoor positioning technology usually refers to some indoor positioning technology means based on wireless communication technology (such as Wi-Fi, low-power Bluetooth BLE, ZigBee, UWB, etc.), through which the person working and living in the indoor space can be provided with positioning and navigation, personnel positioning, asset tracking, and other services.
The indoor Positioning System is a popular application of indoor positioning technology. It can provide real-time location guidance for people so that users can know their location and orientation at any time. It can meet the needs of shopping malls, hospitals, airports, and even large stadiums and other large public buildings of user guidance.
Personnel/assets Location supervision or indoor location tracking is to meet the needs of personnel/assets safety management in the indoor space. It is necessary to understand the location of people or objects in the indoor space in real time so that the manager can better schedule and command. At present, personnel positioning is commonly used in tunnels, pipe corridors, factories, parks, etc., while asset positioning is often used in warehousing, logistics, and other fields.
With the rapid development of technology, there are numerous indoor wireless positioning techniques have been invented, including Wi-Fi, Bluetooth, infrared, UWB, RFID, ZigBee, motion capture and ultrasound positioning, and so on.
WiFi positioning technology depends on the existing WLAN network and uses the received signal strength to track and monitor the complex environment. Based on the location information of network nodes (wireless access points), it uses the combination of experience test and signal propagation model to locate the position of the connected mobile devices, with the highest accuracy of about 1 meter to 20 meters. The biggest advantage of WiFi location technology is its convenience and low cost. However, at the same time, the signal received by WIFI is susceptible to the interference of the surrounding environment, which reduces the accuracy of positioning. Therefore, WIFI positioning technology is not suitable for real-time tracking scenarios with high accuracy requirements. In addition, the Wi-Fi access point coverage range is relatively limited and generally can only cover a radius of about 90 meters.
“Bluetooth” technology is a new wireless communication technology jointly announced by five world-renowned companies in May 1998. Bluetooth positioning is based on RSSI values, and it locates through the principle of triangulation. A positioning system that uses Bluetooth to confirm the physical location of a device involves a complex infrastructure arrangement.
Bluetooth indoor positioning technology is to install a certain number of Bluetooth beacon reference points in the area that needs to be located. By wearing the positioning tag, the personnel will send the signal strength-ranging data to the base station in real time and transmit the data to the solution through the base station. In the calculation server, the positioning calculation algorithm installed in the calculation server realizes the position calculation and realizes the real-time positioning of the target point.
Infrared positioning technology is mainly used in optical sensors. Its technology is very mature, while the price is also low. It is very suitable for moderate upgrades and transformation of the existing equipment, with relatively high indoor positioning accuracy.
However, because the light cannot pass through the obstacles, the infrared ray can only propagate at line-of-sight, which is easy to be interfered with by other lights. Moreover, the transmission distance of infrared rays is short, so the indoor positioning effect is very poor. When mobile devices are placed in pockets or hidden by walls, they do not work properly. It requires the installation of receiving antennas in every room and corridor, resulting in a high overall cost.
UWB positioning technology is a new technology that is very different from traditional communication positioning technology. It not only has centimeter-level positioning accuracy but also has super resistance to environmental interference. It can be used for indoor precise positioning. For example, it can be widely used in detention centers, hospitals, factories, and other places, so as to obtain the precise location information of people or objects in space in real time. It is conducive to the positioning, tracking, or navigation of indoor moving objects. In addition, the UVB tag is rechargeable and has a long standby time, typically lasting about three months.
RFID is radio frequency identification positioning technology. The system does not require mechanical or optical contact with the target. Therefore, RFID is also called contactless automatic identification technology. It is very suitable for long-term tracking and management of the target person or object. With the rapid development of IoT technology, RFID technology will also be the most promising information technology in the new century.
ZigBee technology has the advantage of low power consumption. Zigbee has extensive and rich application scenarios, and the target market mainly includes PC peripherals, home intelligent control, medical care, industrial control, and other fields. ZigBee and Bluetooth also have the characteristics of extremely low power consumption and two-way transmission. They are all part of the Personal Area Network (PAN) architecture. When there is a demand for data transmission, it is immediately transmitted. And Zigbee systems do not require additional hardware support, which is greatly reducing the cost.
At present, most ultrasonic location is based on the reflection ranging method. There are two popular indoor positioning technologies based on ultrasound. One is the combination of ultrasonic and radio frequency technology for positioning. Because the radio frequency signal transmission rate is close to the speed of light, which is far higher than the radio frequency rate, then you can use the radio frequency signal to activate the electronic tag and then make it receive the ultrasonic signal by using the time difference method ranging. This technology has low cost, low power consumption, and high precision features. The other is multi-ultrasonic positioning technology. The technology uses global positioning and can be installed in the mobile robot in 4 directions with 4 ultrasonic sensors. It can overall grasp the data, having strong anti-interference and high precision, and it can solve the problem of robot loss. The precision of ultrasonic positioning can reach centimeter level, and the precision is relatively high.
The NOKOV motion capture system belongs to visual positioning. It covers the capture area of the indoor space through the motion capture lenses arranged in the space and accurately captures the three-dimensional space position of the reflective markers (Markers) placed on the capture target. After processing and computing, the system can obtain the three-dimensional space coordinates (X, Y, Z) of the reflective marker points. The system can also set the rigid body of the target, and further process and calculate the data through professional analysis software. The motion capture positioning technology can obtain the precise position and posture of the target object, which is suitable for scientific research.
The data acquisition of WIFI positioning requires a lot of manpower costs. In addition, WIFI systems require regular maintenance, so the technology is difficult to scale. Another well-known disadvantage of WIFI positioning technology is that it has a relatively weak anti-interference ability to the environment. It is easy to be affected by the surrounding environment when collecting data, so the positioning accuracy of moving objects or people is relatively slow.
The system covers a short distance, and the longest distance may be tens of meters. It can get centimeter-level positioning accuracy at a low cost. At the same time, due to its non-contact and non-line-of-sight advantages, it is expected to become the preferred indoor positioning technology.
This technology can achieve high precision in an open room. The significant disadvantage of infrared technology is that the transmission distance is relatively short, and the obstacles in the environment are easy to block the infrared during transmission. Therefore, the sensors need to be densely deployed, resulting in high hardware and construction costs.
The precision of ultrasonic positioning can reach centimeter level, and the precision is relatively high. But the effective range of ultrasonic localization is relatively limited, ultrasonic attenuation is obvious in the process of environmental transmission.
With the increase in walking time, the error of this positioning is also accumulating. A higher precision external data source is needed to calibrate it. Therefore, inertial navigation is generally combined with WiFi fingerprint, and indoor location is requested through WiFi every period of time, so as to correct the error caused by MEMS. At present, the commercial application of this technology is also relatively mature, and it is widely used in sweeping robots.
UWB can be used for accurate indoor positioning, such as the location of soldiers on the battlefield, robot motion tracking, and so on. As a newly developed indoor positioning technology, UWB positioning technology uses non-sinusoidal narrow pulses of a nanosecond to microsecond level to transmit data and realize positioning, which has the advantages of high precision, high capacity, and low power consumption. It also has better anti-interference and security than the traditional narrowband system. Therefore, UWB technology can be used where very precise positioning needs are required. Such as prisons, public security stations, and other places.
Indoor positioning provides consumers with a good consumption experience, such as searching for empty seats and searching for cars in the reverse direction when parking. There are a lot of consumers and commodities in shopping malls. Google’s market research points out that consumers crave more information about products and a personalized experience while shopping.
In addition to shopping guides in shopping malls and reverse car hunting in parking lots, indoor positioning can also be used in exhibition halls, museums, scenic spots, airports, stations, hospitals, government centers, courts, and other scenes to enable users to have a better service experience.
Indoor positioning monitors the flow of people and presents movement lines in crowded places such as shopping malls and airports. Through the collected data, the enterprises can discover the user’s consumption behavior more accurately, and understand the interest preference behind it, so as to improve the efficiency of operational decision-making and obtain higher business value.
As a relatively mature indoor positioning technology, WIFI technology has been put into use by many businesses in recent years. WiFi positioning generally adopts the “nearest neighbor” method to judge, that is, which hot spot or base station is closest.
RFID location is what we call an electronic tag. RFID positioning obtains the information of the target RFID tag through readers. This information includes ID, received signal strength, and so on. Similarly, the nearest neighbor method, multilateral positioning method, received signal strength, and other methods can be used to determine the location of the label.
At present, the urgent breakthrough of RFID technology lies in how to better protect the user’s security and privacy, and establish international standardization. Compared with other positioning technologies, RFID technology has the advantages of using small electronic tags and low cost. However, the electronic label can only work within a short distance and cannot communicate with other devices. Therefore, it is difficult to integrate data and achieve accurate positioning.
There are two main types of infrared targeting specific implementation methods. One way is to put a can launch infrared electronic tag positioning on the target object, and detect the electronic label emitted infrared Angle and distance by installing indoor infrared sensors to calculate the position of the object. At present, the technology is mainly used for passive positioning of infrared radiation sources such as aircraft, tanks, and missiles in the military, and also for the position positioning of indoor self-propelled robots.
At present, most ultrasonic location is based on the reflection ranging method. The system of ultrasonic technology consists of a core range finder and multiple electronic tags. The main rangefinder is attached to the mobile positioning target, and the electronic tags are placed in a fixed position within the monitoring range.
Bluetooth positioning relies on the RSSI positioning principle. According to different location terminals, Bluetooth location can be divided into network location and terminal location. The specific positioning process can be concluded as:
● Firstly, lay down the Bluetooth gateway and beacon in the zone;
● When users wander into the area, the Beacon broadcast will be transmitted to calculate the distance between users and the beacon (which can be calculated by RSSI).
The terminal positioning system consists of terminal devices and beacons. The specific positioning principle is as follows:
● Lay the Bluetooth beacon in the zone first;
● Beacons constantly broadcast signals and packets around;
● When the terminal device enters the signal range, the beacon will measure its RSSI value, and then calculate the specific location of the device through the mobile phone
Ultra-wideband technology is a new communication wireless technology that is very different from traditional communication technology. It can be used for indoor precise positioning. For example, it can be widely used in detention centers, hospitals, factories, and other places, so as to obtain the precise location information of people or objects in space in real time. It is conducive to the positioning, tracking, or navigation of indoor moving objects. At present, many countries are studying this technology, which has a good prospect in the field of wireless indoor location.
(UWB) positioning technology has received high attention in the indoor positioning field due to its high transmission rate and strong penetration ability.
In supermarkets, airports, hotels, museums, pavilions, and other large indoor scenes, indoor positioning is widely used. In a supermarket with a complex layout, users can find the location of the goods they need to buy and plan the path through the route navigation on the mobile terminal. In shopping malls, museums, exhibitions, entertainment venues, and shops that allow users to quickly locate and navigate their targets.
In the underground parking lot, indoor positioning and navigation help consumers find their cars easily.
For a smart building, the main application aspect is visitor management and real-time trajectory tracking of visitors through visitor cards.
The installation of indoor positioning systems in nursing homes is necessary because the movements of the elderly need constant attention to ensure their safety. The indoor positioning technology can realize real-time monitoring of old people. Meanwhile, the system can playback the elderly’s movement trajectory and the elderly can call for emergency help when facing dangerous situations.
Indoor positioning is also widely used in the field of judicial prisons. With the help of indoor positioning technology, the traditional prison personnel management mode will become simple, quick, and effective. By wearing the anti-disassembly positioning bracelets for the guards and prisoners, the prisoners can be located in real-time, and the track of historical activities can be played back and queried.
In chemical plants, subway construction, tunnel construction, and other high-risk construction sites, personnel positioning management is a critical need. On the one hand, the staff needs to be positioned in these scenarios. When an employee is in danger and calls for help, the rescue personnel can locate the employee in time, which greatly ensures their safety. On the other hand, high-risk places need to monitor visitors to prevent visitors from entering dangerous areas. The indoor positioning system also has many application scenarios. For example, storage logistics.
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