Asset tracking systems can be used to track the position of objects (assets) inside or outside a building. In the inside of a building one might use an asset tracking system to find assets that got lost, whether it be IT devices in an office, medical equipment in a hospital or luggage carts in an airport. One can use asset tracking also to collect position data over a longer period of time and extract statistics to gain insight about the usage and distribution of assets (e.g. finding hot spot areas or bottlenecks).
Several positioning technologies have been developed in the last years to make asset tracking possible not only outdoors but also indoors. Up until now, all technologies have their own advantages and disadvantages. Some of them based on Ultrasound, Ultra-Wideband or BLE Direction Finding are very precise, but are still very expensive and the asset tags supporting supporting these technologies have a comparably low battery life time. Most of these systems also require "line-of-sight" between the asset tags and the infrastructure, which makes them impracticable in closed areas like offices. Other communication technologies not primarily designed for positioning like Wi-Fi or Bluetooth Low Energy (BLE 4.1) can also be used for a rough position estimation. Due to the high signal noise they have can provide only an accuracy of a few meters, but are much cheaper, easier to install and more energy efficient making it possible to run over several years.
The asset tracking system of BlueRange uses Bluetooth Low Energy (BLE) for indoor positioning. A mesh network of fixed Mesh Nodes can measure the BLE signal strength of Asset tags and deliver these measurements to the gateway for position estimation. The mesh nodes can be installed in smoke detectors, lights or placed on the wall. The asset tags will be attached to the objects that should be tracked (assets), which can be hospital beds, shopping trolleys or any other movable object.
The expected accuracy of indoor positioning with BLE is in the range of 0-8m. Latencies of about 5-60 seconds are expected. Both accuracy and latency heavily depend on the arrangement of the mesh nodes. One should follow the guidelines below to find the optimal mesh geometry before setting up the system. The expected battery life time of the BlueRange asset tags is about 2 years. The exact battery life time strongly depends on how often the asset tags move compared to standstill situations.
Although the expected accuracy of BLE is in the range of several meters, the installation effort is comparably low and does not necessarily require line-of-sight multiple mesh nodes in all possible asset locations. Preferred indoor environments of BLE tracking are large buildings like airports or hospitals, where only a rough location estimate is required and a cheap and energy-efficient solution has more importance.
For asset tracking with BlueRange, at least four mesh nodes, one gateway and at least one asset tag are needed. The asset tag must be "trackable" (see Trackable Tags), which means that it must transmit the proprietary
BlueRange Asset Tracking Message. Tags or beacons from other vendors might also be supported in future, but will have limited functionality (e.g. no position stabilization in standstill periods).
To make position estimation possible, a BlueRange asset tag sends a BLE signal containing its identification number periodically. Mesh nodes surrounding the asset tag measure the signal strength (RSSI) and transfer the signal measurements to the gateway. The gateway collects the measurements, estimates a position and publishes its position estimate to the MQTT broker. The position estimates of all asset tags are historized in the BlueRange server and can be accessed using the REST API.
Before setting up the asset tracking system, one should first plan the arrangement of the mesh nodes. The mesh arrangement should be considered from the beginning on, as the mesh geometry significantly influences the accuracy of the position estimates. There are several ways to improve the accuracy and latency of the asset tracking system. Consider the guidelines below to find the optimal mesh arrangement.
G1: Arrange the mesh nodes in a way, so that they span the complete trackable area.
Make sure that the mesh network is big enough, so that all possible asset locations are surrounded by enough mesh nodes. In general, the position accuracy becomes better in central areas of the mesh network, where the tag is surrounded by a big number of mesh nodes. In border areas the position might become unstable, as the situation becomes ambiguous for the tracking system.
G2: Maximize the mesh node density
In general the accuracy improves with the number of mesh nodes. The more mesh nodes are able to receive the tag’s signal, the more measurements can be used by the tracking system to compensate the high fluctuations of the BLE signal strength. If accuracy is of importance, consider adding more mesh nodes to important areas. The distance between the mesh nodes should not exceed 8 meters. A distance of 5 meters or less is recommended.
G3: Minimize the distance between the mesh nodes and asset tags
Both accuracy and latency is becomes better, whenever the tag location is very close to the location of a mesh node. As a rule of thumb, one can say, that the position accuracy grows with the distance to the nearest mesh node. If accuracy is of importance in a certain area, at least one mesh node should be placed in close proximity to the area-of-interest. As soon as the distance between the asset tag and the mesh nodes decreases, the accuracy improves accordingly.
G4: Minimize the height difference between mesh nodes and asset tags
As a consequence of the previous point, it is recommended to place mesh nodes on the same level/height as the assets are expected to move. Mounting the mesh nodes on the ceiling is possible. But one must consider that an increased height difference between asset tag and mesh nodes makes the high fluctuating signals more and more undistinguishable, effectively deteriorating the accuracy.
G5: Minimize the number of obstacles that block the signal between asset tag and mesh nodes.
People or obstacles like walls or furniture deteriorate the position accuracy, as these objects weaken the signal in an unexpected way for the tracking system. Although calibrating the tracking system can reduce the effects of obstacles and walls to a certain degree, one should first check, whether signal blocking can be avoided right from the beginning, e.g. by choosing a different mesh arrangement or indoor environment.
G6: Prefer standstill positioning over motion tracking
Whenever possible, prefer standstill positioning over motion tracking. In standstill, the asset tracking system can collect much more measurements over time, which makes it possible to reduce the signal fluctuations and improve the position accuracy. Furthermore, in standstill the asset tag reduces its power consumption by turning off its motion sensors and transmitting the BLE signals very infrequently. As a lot less measurements will be transferred over the mesh, the number of supported asset tags increases, as well in standstill periods.
G7: Mark unreachable areas in the wallmap.
If it is already known beforehand that certain areas are unreachable for an asset, consider explicitly excluding these areas from the tracking system by coloring them black in a wallmap. The asset tracking system makes sure that tags will not be positioned in these areas. A wallmap limits the space of possibilities and makes it easier for the system to track the assets through the building.
Before setting up your asset tracking installation in a bigger space, you should first start with a small mesh and evaluate, whether BLE tracking is sufficient for your purpose. Start with a functional test inside a room, then test in a larger areas with more mesh nodes.
1. Functional test with 4 mesh nodes (room test):
A simple functional test with a minimum number of devices can be used to check, whether server, gateway and mesh setup has been set up correctly. At least 4 mesh nodes, 1 asset tag and 1 gateway are necessary for this test. The mesh nodes should have a position, where they can be reached by the tag to a very close distance (< 1m distance), e.g. by placing them in the corners of a room.
Infrastructure test: To check, whether the mesh infrastructure is set up correctly, place the asset tag in close proximity (<1m) to a mesh node and wait up to 60 seconds until the asset tag is positioned correctly in the tracking view in the BlueRange admin portal. Repeat this step for each mesh node. If the asset tag is not located correctly, please check, whether you have positioned all mesh nodes correctly on the floor plan.
Localization test: To check, whether the asset tracking system is set up correctly, place the asset tag in the middle of the test area, so that it is surrounded by all mesh nodes and no obstacle can block the signal. Wait up to 60 seconds until the asset tag is located between all mesh nodes with a more or less accurate position.
2. Accuracy and latency evaluation with more than 20 mesh nodes (floor test):
To check, whether the accuracy and latency of BLE is sufficient for your purpose, a mesh network with at least 20 nodes should be set up. The mesh network should cover at least three rooms, so that transitions from one position to another one can be tested with a big distance in between. The mesh nodes should be installed as they would be in productive use (e.g. installed on the ceiling). If installed on the ceiling, check, whether the "mesh node height" is correctly configured in the BlueRange admin portal. After installing, enrolling and positioning all mesh nodes on the floor plan, make sure that a wallmap has been uploaded to your floor, as well. After mesh installation, the tracking system must be calibrated, as described below.
Accuracy and latency test: After setting up the system, you can test the asset tracking system. Start by placing the asset tag in one room for about a minute and then placing it in a different room. If the accuracy or latency are not sufficient yet, consider rearranging your mesh network as described in the guidelines above. In most cases adding more mesh nodes to areas, where location accuracy is important, can significantly improve the accuracy and latency of the tracking.
Asset Tracking setup
In order to set up asset tracking, make sure you have:
Access to a BlueRange Server either by using a cloud installation or an on-premise installation
A BlueRange Gateway that is properly enrolled in your organization (cf. Gateway Enrollment)
At least four Mesh Nodes enrolled in the same network as your gateway (cf. Mesh Node Enrollment)
At least one trackable tag that is enrolled (See Tag Enrollment)
A valid license for using asset tracking. Asset Tracking can be licensed with all of our license types. Ask us for more information.
Please follow our detailed BlueRange Hardware Installation Guide for steps on how to physically set up your hardware.
Before you are able to use asset tracking you need to have acquired a valid license and you need to have a setting on your gateway that activates this feature. See the IoT Features Setting. If no suitable license is available, the status of the gateway will change to "non compliant" when you try to activate the Asset Tracking feature in the IOT Functionalities setting of the gateway configuration. The License can be checked for asset tracking in BlueRange portal. See License.
As mentioned in the beginning, you should already have all necessary devices (gateway, mesh node and asset tags) enrolled in the BlueRange platform. Make sure that you didn’t position the tag on the floor plan with the BlueRange Admin App. A fixed position on the map will prevent the tag from being tracked.
Mesh node positioning
Before you can work with asset tracking, you need to set up a building that contains at least one floor with one network that is assigned to this floor. This floor must have a floor plan. All mesh nodes and the gateway must be positioned on the floor plan. This ensures that all necessary geographic information are available and permits you to see the position of your tracking tags on this floor plan. Also make sure that the width, height and the mesh node height is correctly configured in the floor. If possible, you should also upload a wallmap to the floor. The wallmap is a black-and-white image with the same size as the floor plan. Trackable areas have a white color, whereas non-trackable areas have black color.
Before the asset tracking can be used, it must be calibrated. A calibration can compensate the shielding effect of the indoor environment to a certain degree and enhance the accuracy of the tracking system. Cf. the chapter on Calibration for more info.
Asset Tracking usage
After everything has been set up properly, you can go ahead and check the results.
View the current position of a Tag
If you want to find out the floor and position of any of your trackable tags, log into our Portal and look for the tag. You can navigate to
Devices to get a complete list of devices and search for your device. Alternatively, you can go to the
Network Overview page of the Home Network of the tag. Next, select your tag and open the details page. You’ll see a map of the floor where the tag is currently located along with its position.
Notice, that you will also be able to see where the tag is currently located in the building structure, including floor, room and zone in the information panel.
View the current and historic position of all BlueRange Tags for a Floor
If you want to see all tags that are located on one floor, you can open our Portal, go to your building and select one of the floors in the navigation pane on the left. Next, open the
Tracking tab. You’ll get a list of all devices that are currently being tracked on this floor.
History to follow the historic positions of your tag.
Find out where your tag has recently been
We also offer another view that is helpful for determining the historic movement of a tag. Go to any of your tags that is being tracked by either selecting it from a list of devices or by double-clicking on it on the map view. Next, select the
You will now see a list of position changes that shows where your tag has been in the last two weeks. The position icon on the left tells you if the tag has been located or if the location has been temporarily lost or the tag was moving.
Each entry will show you the location in your building structure, where your tag was located. While the graphical representation on the floor plan is useful to monitor the recent movement, this list is useful to find out in which room our zone your tag was staying for a prolonged time.
Using the carousel arrows to the left and right allows you to view the position based representation that accumulates the events based on the positioning
View the list of tracked devices
Quickly finding a device that is being tracked is possible though the
List of tracked devices which is available under
> Devices > Tracked Devices. You can use this list to quickly find out where your devices are currently located.
Receive Geofence Events
When using Geofences, our platform generates MQTT events once a trackable tag enters or leaves a defined region. You can process these events from all clients that are connected to our BlueRange MQTT Broker. If you want to browse and verify these events, take a look on how to use the MQTT Explorer.