November 27, 2018 - 1 comment.

Possibilities of indoor location

The need for the location of objects is increasing all the time. Military and other industries such as transport and logistics strive for electronic systems that easily allow locating drivers or loads. Of course a GPS is the most well-known system of this type. This system was created precisely for the army's needs in the 1970s. It allows absolute location on the whole earth with an accuracy of several meters.

Making GPS available for civil applications has become a real revolution in the development of technology. Car navigations, fleet systems (both in logistics and popular taxi services) have significantly changed the character of business.

However - this technology has its limitations. The most important one is the mentioned accuracy - measurement with a precision of up to several meters is sufficient for tracking deliveries at the container's level, but not at the level of individual goods. Another problem is the availability of the system - which is only outdoor - this excludes its use in buildings (eg factory halls or warehouses).

With the development of online shopping, logistics is growing importance for the economy. It is the key to the development of virtually any business based on trade items. The growing needs in this area have forced the creation of a positioning technology that could work with greater precision and would be suitable for an indoor use. This is how the class of solutions known as RTLS or Real Time Location Systems was created.

These solutions usually use different types of tags attached to the monitored object and special devices mounted on the tracked area - to read the position of the marker.

These systems can be divided in various ways:

  • systems fixing a relative or absolute position
  • symbolic location systems

The first one determines the position by absolutely specifying it in the form of latitude and longitude (such as GPS), or in relation to an object.

The second one is able to indicate the area in which the marker is located, or indicate that it has passed a certain point where the reading device is located.

Various technologies are used to implement these functions. Symbolic systems are usually based on RFID tags. They are small, often flexible (in the form of a sticker) tags without their own power supply. During the reading process, the reader provides them an electromagnetic pulse that powers them, and they emit back the information stored in them. Most systems that use access cards work on this principle.

When the location is based on coordinates or position relative to the reader, there must be active markers that are battery-powered.

This is where you should mention the way of determining the location: to find out where an object in space should be located, determine its distance from other objects whose position is known. The more such distances, the more accurate the position, but the minimum number of reference points is 3. (vid: https://www.youtube.com/watch?v=1U7ROVno2ys&t=301s - click for more information about this method). As you can see, distance is the key for location systems. This is usually done by measuring the time it takes for the signal emitted by the tag (location marker) to reach the receiver. Different types of waves are used in various systems, solutions using: ultrasound, light and radio waves are available on the market.

Every solutions has its pros and cons though. The selection of the correct one depends on the place of application, working conditions, required accuracy and price.

Ultrasound systems are used for the internal location where the located device is a smartphone.

The advantages: 

  • relatively low installation cost
  • no need to mount additional systems in the phone
  • the system becomes trouble-free for the recipient. 

    From the point of view of the end user - all you need to do is to install the right application. This receives signals from installed emitters and determines the location on this basis. The downsides are the low resistance to acoustic interference, which excludes use in noisy spaces - such as factory halls. The preferred area of ​​use is for example: a shopping mall - as a system for navigating around commercial spaces.

A similar situation occurs in systems that use light and / or vision systems. Such solutions are useful, for example: to track players on the pitch (after processing data from cameras located around) or hockey players. However, any obstacle blocking the beam of light between the tracked marker and receiver excludes such system. This type of object tracking will not be used in warehouses or factory halls, where a rapidly changing work environment can cause problems with the "visibility" of tags.

The most universal systems are those based on radio waves. There are two most commonly used approaches:

  • distance measurement based on the signal strength of transmitters of commonly used communication systems - such as Bluetooth or WiFi
  • using proprietary protocols and non-standard radio wavelengths

The first approach has the following advantages:

  • a relatively low implementation price
  • the possibility of cooperation with commonly used devices (tablets / smartphones) without additional equipment
  • no legal restrictions as to the availability of the radio band used

The disadvantages are:

  • relatively low accuracy of measurement (especially objects in motion)
  • susceptibility to interference by other WiFi networks or Bluetooth transmitters in the environment
  • greater vulnerability in the context of system security.

The second approach is characterized by:

  • greater accuracy of measurement (up to several centimeters)
  • less susceptibility to interference
  • greater security
  • the ability to track many objects simultaneously
  • the ability to accurately track objects in motion

The disadvantages are:

  • the slightly higher price of such systems
  • the necessity to use specialized transmitters and markers
  • limitations resulting from the radio bands used in a given solution - in some countries those parts of the band are reserved

WTHe decision on which approach will be used depends on the requirements for such a system. In case of shopping malls, public spaces and when the system is aimed to be used by individual users, an approach based on e.g. Bluetooth is best used. The possibility of cooperating with popular smartphone models without additional equipment will be crucial aspect in this situation.

However, if the location solution is used in industrial spaces - such as logistics centers, factories, warehouses - the accuracy and reliability of the system is crucial. Here, a system using a more advanced proprietary protocol will be recommended.

At Summer Agency we have extensive experience in designing and implementing systems of both types: our experience in designing applications, interfaces and electronics will create a full navigation system in the shopping gallery. For professional applications, we possess our own RTLS solution with high location accuracy, reliability and security level.

If you are interested in implementing the RTLS system in your company, to improve the quality and comfort of work, and to increase productivity .

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