Indoor location systems

What is and what are the location systems for?

Knowledge about where someone or something is located has become an important requirement in multiple fields, such as in the case of military companies or services.
In outdoor environments, GPS is the most widely used solution, practically universal, to obtain a “precise” and fast location anywhere on the planet. This technology is widely extended with applications such as car navigation systems, fleet management or the location of emergency calls.

For indoor location, this technology presents problems with signal attenuation, so is not possible to obtain such good results. In location systems, accuracy and range are important aspects, which depend on the signals used and, therefore, on the technology on which they are based. In the following sections you will be able to know what options we use when we want to locate objects indoors.

How is indoor location done?

In recent years, a lot of time has been invested in developing solutions to make the location indoors as powerful as the one we have outdoors, taking into account the limitations that appear since there are no previous maps and the precision obtained in the location should be much larger (GPS provides 10m approximations). This situation has led to the appearance of numerous technologies that try to cover indoor applications, such as UWB, ZigBee, WiFi or Bluetooth.

In general, the location is carried out in two phases:
• The estimation of distances, which is based on the measurement of different parameters (angle, level and arrival time) of the signals transmitted between the reference nodes and the element to be located.

• The calculation of the position, which is carried out using varieties of algorithms, ranging from geometric calculations to those that take into account the trajectory and the previous position.

The most used techniques to estimate the position in this type of wireless systems are:

• Trilateration: calculates the position of the node by measuring the distances to various reference positions (beacons). At least three non-collinear beacons are required for 2D location.

• Triangulation: similar to trilateration but is based on angles and distances. Only two angles and the distance between two points can be used for 2D.

• Multilateration: like triangulation, but uses the difference of the arrival time of the signals to calculate the distances.

• Scene analysis: analysis of the scene from a specific point, either with a camera or another type of sensor, in order to detect changes in it. An example would be our Project in which we locate the elements thanks to the vision camera.

• Proximity: determines when an object or person is near a known location through pressure, touch, capacitance, tags or logins sensors.

Location devices and technologies

There are different devices and location technologies that can be used, we tell you some of the most used:

Beacons or BLE (Bluetooth Low Energy)

A beacon is a low-energy device, which generates a bluetooth low-energy signal (BLE) to other mobile devices near it without the need for prior synchronization. These beacons transmit a universal unique identifier that can be collected in an application to carry out certain actions, such as obtaining its location.

Their error is less than 1 meter, they have a range of up to 90 meters and their latency is determined by the configuration of the beacon.

It is one of the solutions that has been implemented for the longest time in various applications, either in factories for the location of assets, or in stores to locate the area of the premises in which we are located and offer us personalized offers through the communication of our smartphones with these beacons. We can also find it in some museums to locate works or take guided tours.

RFID

RFID is a set of technologies designed to read labels or tags remotely through the use of a reader, in such a way that, when the reader is in the area where these labels are issued, there is an exchange of information between the devices.

The labels can be of passive type (without batteries, since they make use of the energy of the waves emitted by the reader to carry out the communication) or active type (they include a battery inside). The measurement ranges are less than one meter in the case of the passive ones, while for the active ones they are between ten and one hundred meters. NFC, increasingly present today, is a subset of RFID technologies that limits the transmission distance to a few centimeters in order to improve security.

Other technologies like LiFi, WiFi

The use of WiFi and LiFi communications is currently being investigated, developing low-energy systems that allow good results to be obtained in indoor locations. At the same time, progress is also being made in various techniques such as the use of acoustic beacons at non-audible frequencies or the use of all the sensors integrated in the smartphones in order to improve the precision of the locations.

Applications of beacons or sensors in indoor location

There are numerous applications where sensor technology and beacons can be used indoors, both for the industrial environment and for other sectors.

• Localization of assets, tools and equipments. Know where your most important teams and assets are at all times
• Product localization. Know where your product is in the factory to make its traceability.
• People safety. Prevent people from approaching dangerous areas if we place a beacon in the danger area that alerts the bracelet or mobile phone of the approaching worker.
• Retail and marketing. Knowledge of the flow of people, in which articles or in which areas our client is most interested.

Do you want to apply indoor location in any of your Projects? Contact us!