Several Usage of UWB Indoor Positioning

2022-09-26 16:16 Duniot Factory
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20220827

UWB+PA

The communication distance of UWB is 50-100 meters. In the case of channel 2, 100 meters is guaranteed

Due to serious co channel interference, Bluetooth is generally 30-50 meters away from 2.4G WIFI

UWB+PA can cover more than 500 meters, similar to tunnel scenarios. This can greatly reduce the number of base stations, hardware costs and construction

The communication between UWB base stations can reach more than 1km by using directional antennas

Adding PA will increase the power consumption and cost of labels

UWB+acceleration sensor

Purpose: static state, low power consumption of labels, awakening UWB during movement

The price of ordinary acceleration sensor chips is superior to that of MEMS, so most UWB tags on the market now integrate acceleration sensor chips to achieve power management.

UWB+barometer

Theoretically, TDOA and TOF triangulation can measure X/Y/Z three-dimensional coordinates, but only if there is a height difference between base stations, similar to GPS satellite positioning. However, it is impossible to guarantee the height difference of the actually deployed BTSs. Therefore, in the actual application environment, the X/Y coordinates are basically measured, and the height Z cannot be obtained through the triangulation algorithm. The height value of sub meter level can be obtained by using the elevation algorithm of barometer pressure difference.

Premise: The label and the base station circuit board support the air pressure sensor

The air pressure difference between the base station and the tag, and the height measurement, are currently considered to be a touchable technical means for indoor and outdoor height measurement.

UWB+NFC/RFID

NFC/RFID is a passive electronic tag, which uses magnetic field excitation to generate random current to read data.

The working frequency (13.56MHz) of RFID is much lower than that of UWB (3.2G-6.7GHz), and the energy of UWB signal is much higher than that of RFID. Therefore, if UWB and RFID are arranged in the same structure, the influence of UWB on RFID signal should be considered.

In addition, in order to ensure RFID sensing and experience, it is necessary to deploy sensing coils around the label. The deployment of UWB modules and batteries also needs attention.

UWB+INS

MEMS itself is a sensor, which requires some CPU computing power to realize inertial navigation algorithm and communication function.

The accurate definition of UWB and INS fusion should be reverse TDOA and INS fusion

The high cost of MEMS sensing is also considered. The cost of common MEMS sensing is 60-80

Inertial navigation needs a lot of real-time sensing information and real-time calculation, which should be implemented on the label side, which is why it is suitable for fusion with reverse TDOA.

As with reverse TDOA, the cost and power consumption on the label side increase, so it is suitable for smart phone or car side location label scenarios

UWB+RTK

UWB is currently a representative technology of indoor high-precision positioning, while RTK technology based on GNSS is a representative technology of outdoor high-precision positioning. The goal of UWB and RTK fusion is to achieve indoor and outdoor high-precision positioning. However, the following points should be noted:

Neither UWB nor RTK is a low-power technology, which consumes more than ten times more power than traditional labels

At the same time, the Internet of Things communication similar to NB or CAT1 needs to be added, which also increases the cost of labels

The cost of UWB and RTK integrated labels should be close to 1000, far more than other types of positioning labels

RTK requires more visible satellites, so MEMS inertial navigation will be used to supplement satellite signal failure. The use of MEMS further increases the power consumption and cost of labels

Due to the high power consumption, the battery capacity is relatively large, basically more than 2000mAH, and the label volume is also large

Specific scenarios are similar to car side or smartphone side, so it is recommended to integrate the two technologies

UWB+BLE

The first product to be put forward for integration of UWB and BLE should be Airtag;

AirTag:

BLE is used for long-distance tens of meters detection, and UWB is used for accurate positioning of the last ten meters

Low power consumption advantage of BLE

The precise positioning advantage of UWB

Integration of UWB positioning application and BLE in 2B market

The problem to be solved is the low power management of labels in non UWB application scenarios.

Non UWB application scenarios, labeled as BLE beacon working status

Enter the UWB application scenario, and the label wakes up the UWB through BLE

Leaving the UWB application scenario, the label switches to the BLE beacon mode

UWB+Bluetooth gateway

UWB tag fusion Bluetooth gateway module

The Bluetooth gateway obtains the Bluetooth sensor data around (within 30 meters)

The UWB tag with PA is used to realize data communication of 300-500m

UWB+4G、NB、LORA、WIFI

Traditional UWB base stations generally use the POE method to achieve power supply and network communication. However, the distance of the network cable is limited to 100 meters. In long distance scenarios such as tunnels (200 meters to 500 meters) or similar industrial and outdoor environments, the wireless communication method is the best choice.

Long distance wireless communication options:

The 4G/CAT1 and NB modes of the operator are adopted, provided that the positioning algorithm needs to be implemented on the base station in advance.

LORA is a narrowband long-distance wireless communication network. When the number of tags is small, LORA Internet of Things can be used to achieve wireless upload of location results. The premise is that the location algorithm needs to be implemented on the base station in advance.

In some cases, similar tunnels use leaky cables to achieve wireless WIFI coverage. It is also an option for positioning base stations to use WIFI wireless upload, provided that the positioning algorithm needs to be implemented on the base station in advance.


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