B-Mobile Personnel & Asset Tracking Solution

B-Mobile Personnel & Asset Tracking Solution https://www.lansitec.com/

Overview  ‘B-Mobile’ stands for ‘Beacon Mobile’. Bluetooth beacons are deployed on assets or personnel.

Bluetooth gateways are deployed at fixed locations. This intelligent asset management solution is based on the lastest LoRa technology and Bluetooth technology. The solution uses the latest IoT technology to strengthen the management of onsite personnel, acquire real-time location information of personnel and assets, and precisely document the time when personnel enter and leave the site. Geo-fences are supported to specific regions of the site to control the in and out of personnel. It also performs an analysis of the duration of vehicles staying on construction sites. Therefore, the management level and efficiency is significantly enhanced, safety risks are reduced Features of this tracking system are:   Wide network coverage   Easy to install, no need to set premises distribution system   The maximum standby time of Bluetooth beacons can be up to several years This document aims to introduce the composition, features, software development methods, and project implementation methods of the system.

2. Network Set-up Solution

ď‚š Personnel Tracking Management Deploy Bluetooth gateways at fixed locations. Personnel wear Bluetooth badges/bracelets and messages are sent to the nearby Bluetooth gateways. The Bluetooth gateways then forwards received information to the server via the wireless LoRa network. Finally, the location of personnel is calculated by the server.

Other forms of Bluetooth devices installed on the assets can also be used for asset tracking management, such as vehicle management in parking lots.

ď‚š System Composition 1) Bluetooth beacon (or called Bluetooth badge): broadcasts Bluetooth signal according to set duration, worn by personnel, or put on the dashboard inside of the vehicle.

2) Bluetooth gateway: receive nearby Bluetooth beacon messages and reconstruct them, then transmit Bluetooth beacon messages via LoRaWAN. 3) LoRa gateway: transmits the data sent by Bluetooth badges to the cloud via 4G or Ethernet.

4) Tracking engine: calculates the location of devices/personnel, deployed at Alibaba cloud.

5) Map engine: marks the location of Bluetooth beacons, objects, displays the location of the device or personnel according to requirements, cloud based. 6) Application server: web services and APP services.

Tracking Principles

ď‚š In this scenario, the Bluetooth gateway is deployed at a fixed location, such as the lobby or walls of the corridor. When a person who wears a badge beacon passes by, the badge receives beacon information. Therefore, the system knows that the person is close to the gate, but it is unable to identify his/her exact location. It is also able to calculate the distance between the beacon and the person based on received signal strength.

However, it cannot determine the direction. Thus, single-point tracking is only suitable for rough tracking. Please refer to the article in the link below for more information about distance calculation.

ď‚š Since people usually walk at a fast speed, it is suggested that the Bluetooth broadcasting interval of the badge beacon should be set to 800ms. The Bluetooth receiving function of the indoor Bluetooth gateway and badge Bluetooth gateway is always on. As long as the distance between the gateway and the beacon does not exceed their coverage range, the signal sent by the beacons will not be lost. It has been tested that the maximum outdoor transmission distance reaches 80 meters without any obstruction. The maximum indoor transmission distance is between 10~30 meters. The transmission distance varies depends on the obstruction. For the solar Bluetooth gateway, the window for Bluetooth positioning function is three seconds. Thus, the broadcasting interval of the beacon should be less than 1.5 seconds to ensure that the messages can be received by the gateway.

ď‚š Even though signal sent by Bluetooth beacon can be received by gateways in the next room, the signal is generally very weak. The difference between the two RSSIs can be up to 20dBm. Because of the interference in 2.4G band as well as the multipath effect, the signal strength received by the gateways differs noticeably. The relative distance between beacons and gateways changes constantly, which then leads to less accuracy in positioning.

Two-point positioning ď‚š Two-point positioning is suitable for long and narrow areas such as tunnels, passages, and roads. Gateways are deployed at both ends of the passage with 10~15 meters distance.

The gateway forwards the received beacon messages to the server. Then the server calculates the location of the beacon. The precision is around 3~5 meters. There is a time difference between two received messages of Bluetooth gateways. There is also a time difference among LoRaWAN network servers when they receive those messages. The time difference can be seconds or longer depending on different reporting intervals. Therefore, using such a method for personnel tracking tends to have relatively less accuracy. Thus, we suggest using this method for asset tracking. Generally, assets stay at a fixed location for a longer period. During this time period, servers acquires multiple groups of data to ensure the tracking accuracy.

Triangulation ď‚š Since the distance between the tracker and the beacon varies, the beacon receives different signal strength. Therefore, the distance between the tracker and its three nearby Bluetooth beacons can be calculated. Beacons are deployed at a fixed location with known longitude and latitude. Thus, its relative longitude and latitude can be calculated as shown in Figure 2. For large open space indoors, we generally use 2x2 matrix deployment method in projects, which is deploying Bluetooth gateways every ten meters.

Since the distance between beacons and Bluetooth gateways varies, the signal strength varies. Therefore, the distance between beacons and three nearby Bluetooth gateways can be calculated. Bluetooth gateways are deployed at a fixed location with known longitude and latitude. Thus, the relative longitude and latitude of the beacon can be calculated.

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