What Is RTLS?
The acronym RTLS stands for the real-time locating system. RTLS is often referred to as RTLS systems, which is incorrect, but convenient.
RTLS is nearly the same as an indoor positioning system (IPS)
Although not limited to indoor positioning systems (IPS), when talking about RTLS, it is usually the various types of indoor positioning systems that are meant. Sometimes, they are also called local positioning systems (LPS).
GPS is GNSS. It is not RTLS
Although not limited to indoor positioning systems (IPS), when talking about RTLS, it is usually the various types of indoor positioning systems that are meant. Sometimes, they are also called local positioning systems (LPS).
GPS is also an RTLS system, but GPS belongs to global navigation satellite systems (GNSS) along with GLONASS, Galileo, and BeiDou.
RFID is not a real RTLS
RFID stands for Radio Frequency Identification. Just as BLE, WiFi, LoRa, and ZigBee, which are not designed for positioning systems, can still be used for this localization and navigation, and RFID is not a positioning system but, with a particular stretch, can still be used for this purposes.
Of course, the stretch is serious. You don’t know the location of your mobile object, your mobile beacon, or your tag. You know whether the tag was registered within 0.1-1m from an RFID reader. Typically, 0.05-0.1m and only for some special readers – within 1m. But you don’t even know the distance. You only know yes or no. You don’t have the XYZ coordinates of your mobile beacon. You have only XYZ of your RFID reader.
Many applications of RTLS
Since we focus on industrial applications, we do not touch in the article on other areas, for example, retail, healthcare, hospitality, agriculture, security, etc. There are very many areas where RTLSs are used.
RTLS for palette tracking? - not recommended
Typically, when talking about RTLS, one talks about mobile assets: forklifts, vehicles, people, robots, AGVs, and drones. Much less about palettes.
Palettes are semi-mobile. Yes, they are moved, but they don’t move. Palettes are on the borderline between RTLS and RFID or some other identification methods, for example, QR/bar code identification with the help of mobile robots, drones, or people.
One of the significant problems in warehousing is misplaced palettes. But employing RTLS for that is a bit of an overshoot because:
- Mobile beacons are expensive because they have a battery, electronics, etc. Typically – tens of USD/EUR or more per mobile beacon (tag). To track forklift – fine. To increase the safety of people – it is okay. But to put it on thousands of palettes – too expensive and still doesn’t solve many problems
- RFIDs are better, but as discussed, they don’t give location. They report: “I am close to the reader”. One needs to know the location of the reader to know the location of the palette
- RFIDs are far less expensive than mobile beacons for RTLS. But the reader must be mobile
- A mobile reader can have various forms: a person with an RFID reader and a robot/drone with a reader. It can be a static RFID scanner embedded in gates. The RFID read out when the palette or the object with the RFID passes through the gate
- The same is valid for QR/bar code readers
Typical applications of RTLS
- Forklifts tracking for productivity
- Forklifts and vehicles tracking and geo-fencing against people and other vehicles for safety
- Forklifts and vehicles tracking and geo-fencing against AGVs
- Assets/palette tracking
- People tracking for productivity
- Geo-fencing zones in broader terms for safety
In general, usage in manufacturing is pretty close to warehousing and intra-logistics because they more or less have the same tasks and applications. Manufacturing has more variety:
- People tracking
- Vehicles tracking
- Geo-fencing zones for safety
- Cranes/hooks/load tracking against vehicles, people, AGVs
- Cranes tracking in order not to violate borders of the construction area
- Hooks against vehicles and people
- Cranes against drones
- People against dangerous zones – all sorts of geo-fencing zones
- Vehicles tracking and geo-fencing against people. Safety
- Vehicles tracking and geo-fencing against AGVs. Collision avoidance
AGVs tracking and geo-fencing against people. Safety
- Autonomous robots
- Autonomous drones
- Autonomous vehicles
- People tracking for productivity
- Automatic task assignments for gauges readings or maintenance work based on people’s location
- More limitations due to explosion protection requirements => more expensive, heavier, bulkier, lower other performances
What are real-time locating systems good?
The answer to the question of what real-time locating systems are good will depend on what you are looking for: accuracy, low latency, price, range, easiness of deploys, easiness to operate
- ±2cm: Marvelmind Indoor “GPS” – ultrasound-based RTLS
- ±10..30cm: UWB
- 1-2m: BLE with AoA
2-5m: BLE - Gate-level: RFID
- 100-400Hz and 5-10ms latency: IMU+Ultrasound or IMU+UWB sensor fusion
- 4-50Hz and 20-100ms: Marvelmind Indoor “GPS”, UWB, BLE – depending on the settings and mode
- RFID – not such thing as location update. RFID is not a real RTLS
Price of the system, price of the mobile beacon (tag), price of the stationary beacons and supporting infrastructure, installation costs, maintenance costs – many factors. Ultimately, it depends on the exact configuration, requirements, specs, etc.
- ~1 cent: QR/bar code – Cranes tracking in order not to violate borders of the construction area
- ~0.1 USD: RFID tag
- ~10-30 USD: BLE tag
- ~50-200 USD: UWB, ultrasound tags. Ultrasound stationary beacons. Active RFID tags
- 100-1000 USD: UWB anchors; specially protected tags (IP69, EX-protected, etc.)
– Global: GPS/GNSS
– 10-1000km: Cellular networks
– 10-50km: RTK GPS
– 100-500m: Marvelmind Indoor “GPS” with multiple submaps, UWB, BLE
– up to 50m per submap: Marvelmind Indoor “GPS”, UWB
– up to 10-30m per submap: BLE
What are RTLS tags?
RTLS tags or RTLS mobile beacons are wireless devices placed on mobile objects to track their location inside the coverage area of RTLS (for example, building, warehouse, factory, hospital, etc.). You don’t track a person – you track their RTLS tag/mobile beacon. You don’t track a forklift – you track its RTLS tag.
Difference between RTLS tags and RFID tags
An RFID tag can be considered an RTLS tag but a very primitive and rudimentary one. Typically, RTLS systems provide 2D (XY) or 3D (XYZ) coordinates of the RTLS tags. At the same time, the RFID tags provide gate-level coordinates only. An RFID system doesn’t give real-time coordinates of an RFID tag until the tag is placed on the RFID reader, or the RFID tag shall pass through an RFID portal. Therefore, calling the RFID system a real-time locating system is a big stretch.
Review and comparison of different types of RTLS
Study more about different types of RTLS and RTLS technologies:
- Indoor navigation & positioning (PDF) – review and comparison of industrial indoor positioning technologies and methods
- Indoor navigation & positioning (YouTube video) – video based on the PDF above with additional insights