Table of Contents
What Is RTLS Technology? (Real-Time Location Systems)
RTLS, also known as “RTLS indoor tracking” or “indoor positioning system”, is a technology solution that provides real-time tracking of inventory, staff and equipment. The most common RTLS meaning in terms of tracking includes both monitoring the location of these assets and their condition. It alerts users to configurable events, such as a box with finished products taking a hit from a forklift truck or a person straying into a hazardous zone.
RTLS is a combination of hardware and software.
Real-Time Locating Systems (RTLS) are typically used to track and manage manufacturing and logistics operations. It provides a real-time link between what’s happening on the work floor and the information technology (IT) enterprise system, such as an ERP, MES or WMS.
How Do Real-Time Location Systems Work?
In an RTLS, the Anchors determine the distance from them to each Tag. As many Anchors can see any particular Tag, by combining these Anchor-to-Tag distances the location of each Tag can be determined through a family of algorithms commonly known as multi-lateration. Redlore has improved the state-of-the-art algorithms for a location accuracy of 30cm (1’), all with long-life battery-powered Anchors.
The Positioning Engine’s job is to calculate the position of the tags (see the section on how an RTLS works). The positions can then be used in many ways, such as displaying the position on a floor plan of the facility, informing the production system about the stock levels of raw materials, alerting a supervisor when someone strays in a protected zone, optimizing forklift truck driving routes, etc.
Use Cases for RTLS in the IoT Industry
Material Tracking and Inventory Management
Having the right materials at the right time and at the right place in the facility is the key to efficient manufacturing and logistics operations. When raw materials are lacking the machine cannot produce, resulting in revenue loss. Traditionally, material flows are managed through barcode, RFID, and, even still today, with pen and paper.
RTLS can not only automate the inventory counting, but with RTLS the location of all the material is known in real-time. It can track the entire production process, for example, when only a single unit of input material is detected at the (Kanban) buffer in front of a machine, it can automatically signal to the preceding process to supply new material.
RTLS also keeps track of the integrity of spare parts. By means of RTLS Sensor Tags the health of the part is monitored in real-time and they send alerts to damage such as from a fall, a lateral impact, vibration, tilt, excessive temperature or humidity, etc.
Moreover, RTLS guards high-value assets and provides a chain-of-custody by monitoring every motion and sending alerts when assets move in or out of predefined zones, so called geo-zoning or geofencing.
Equipment Management
As one of the biggest applications of RTLS, equipment management provides many benefits: tracking the location enables fast retrieval, reducing search time and reducing idle time; easy retrieval has also proven to reduce the need for equipment by 20%, RTLS sensors track the utilization of the equipment, enabling preventative maintenance and increasing Overall Equipment Effectiveness (OEE), knowing where the equipment is at all times provides chain of custody and security compliance.
Tracking equipment location can automate a process that previously relied on error-prone barcode and RFID scanning, RTLS sensors monitor the health of the equipment and alert of undesired handling such impact, vibration and excessive heat, and route tracking enables optimizing internal logistics flows and increase productivity.
RTLS in Healthcare
The healthcare industry can greatly benefit from Real-time Location Systems. Finding the mobile equipment, such as an ultrasound machine, when it’s required is a major cost saver and source of convenience: no labor time is wasted searching for that one machine so equipment utilization increases dramatically, reducing the total equipment base and decreasing the capital tied up in equipment.
RTLS in the healthcare and elderly care industries will also track patients at risk of wandering and generate alerts in real-time. It helps guard the well-being of the patients and reduces the burden on the staff.
Naval Application
In the naval industry RTLS helps guard the safety and security of the people, the integrity of the equipment, and the efficiency of the operations. It tracks the crew members on board the vessel with an automatic check-in/check-out when people enter or leave the ship. Crew location and counting is available in real-time in case of a dangerous incident such as a fire. A man-down situation is detected automatically.
Equipment, both mobile and stationary, is tracked and the condition (temperature, impact, fall, tilt, vibration) is constantly monitored and adverse situations detected. Stationary sensors can, in addition, provide early fire detector warnings as a secondary detection network overlaid on the legacy fire detectors.
Vendor Managed Inventory (VMI) and Consignment Stocking
In (VMI) programs or any other form of Consignment Stocking the vendor needs to keep track of stock levels and manage assets at the customer’s premises. RTLS provides huge benefits by automating the process and avoiding the need for human interaction and the effects of human error.
Stock tracking is automatic and real-time, triggering an invoice event as soon as the goods are consumed. In VMI the consumption of goods is automatically forwarded to the IT system and triggers a reorder as needed, avoiding stock-out situations and line-stops.
People Tracking
RTLS provides People Tracking for the safety of the people involved and the security and efficiency of the organizations involved. People wandering into hazardous or protected zones are detected and alerted in real-time; the checking in and out of people is automatic and automates contractor timesheets and billing. It provides automatic people counting and positioning in emergency situations and provides task time tracking to increase work productivity.
High-Value Asset Management
RTLS reduces damage and avoids spoilage in High-Value Asset Management for pharmaceutical products, spare parts, food, and just about any industry where the loss of the asset represents a high value. RTLS detects when the asset is subjected to an excess of mechanical, thermal or other stress and sends out early warnings as to the prevailing conditions and the location of the asset at risk.
Additionally, chain-of-custody is often required for high-value goods, in which case the check-in/check-out and position tracking capabilities of RTLS provide proof-of-custody. Finally, in case certain parts are required for the uninterrupted operation of an activity, the RTLS monitors in real-time if all required parts are in stock and if any damage has been incurred.
Loading & Unloading Monitoring
Components in an RTLS Solution: The Complete List of RTLS Devices
Tags & Beacons
RTLS Tags are attached to the assets, which can be items and people. A tag, sometimes called a beacon, tracks the location of the asset. In addition, most tags contain sensors to monitor the condition of the asset, such as temperature, mechanical impact, tilt, vibration, etc.
Tags come in many varieties, with different sensors, different positioning accuracies and different battery capacities.
Anchors
Anchors are devices that are spread throughout the infrastructure, typically with one Anchor every 15m (50’) on a grid. They form the RTLS reference points that determine the location of the Tags. The Anchors are fixed to their locations and assigned to physical objects on a floorplan represented on the Control Tower software application.
Unique to RedLore are wire-free Anchors. These are Anchors that will last for many years on a single battery charge and don’t require any electrical wiring nor data cabling. Thanks to the wire-free Anchors, a RedLore RTLS solution typically costs 85% less to install than competitive solutions.
Modules & Gateways
RTLS Sensor
An RTLS Sensor is an RTLS Tag with additional sensors to monitor the condition of the asset they are attached to. RedLore provides many RTLS Sensor Tags to monitor temperature, humidity, motion, impact from a fall, lateral impact such as from a forklift truck, tilt, vibration, light level, sound level, magnetic field, IR temperature-at-a-distance, PIR motion-at-a-distance, etc.
Software Location Engine, Control Tower & API Access
RTLS systems require a Location Engine. The Location Engine software is a cloud software component that determines the location of each Tag. For each tag it receives the distance to all anchors that are in wireless range of the Tag. Through an algorithm known as multi-lateration, the Anchor-to-Tag distances are combined to accurately estimate the location of the Tag.
RedLore has improved on state-of-the art multi-lateration algorithms to provide a high positioning accuracy of 30cm (1’), all with the use of RedLore’s unique wire-free Anchors.
All the location and sensor condition data is visualized in RedLore’s Control Tower, called RedBoard, a powerful web-application sometimes called the application software. In addition, RedBoard provides business insights and services built on top of location and conditions, and thus manages the tagged assets. For example: ending alerts when assets move in or out of a zone, informing users about low stock levels in a Vendor Managed Inventory Process, alerting users if a box of raw materials has titled too far, monitoring the locations where perishable goods have spoiled, etc.
As an alternative to the RedBoard Control Tower, all data can be passed to an external IT system (ERP, MES, WMS) though an Application Programming Interface (API).
Mobile Scanner App
What Location Indicators Can Be Used to Determine the Distance Between an Anchor and a Tag?
Determining the distance between an Anchor and a Tag is the first step before calculating the position of the Tag. There are several ways in which the Anchor-Tag distance can be estimated, the most important ones being the Received Signal Strength Indicator (RSSI) and Time of Flight (TOF). These location indicators are explained below.
- RSSI: When a Tag sends a message to an Anchor, the signal becomes weaker the further it travels through the air, which is called attenuation. So when you know the attenuation, you know the distance travelled. The attenuation is easily calculated from subtracting the received strength from the transmitted strength. The problem with the RSSI indicator is that the signal from the transmitter to the receiver not only travels through air but also through objects like inventory and people. These objects weaken the signal much more than air. That’s the reason why RSSI positioning is typically only accurate up to 3 to 5 m according to some organizations for standardization like ISO. Wi-Fi and Bluetooth positioning are based on RSSI to track the location data.
- TOF: The time a message travels between the Anchor and the Tag is measured. As wireless signals travel at the known speed of light, the travel time is a direct indicator of the distance. The speed of light varies depending on what the signal is travelling through (air, water, wood, etc.). But, as air usually represents the majority of the path taken, these objects don’t have a large effect and a positioning accuracy within 30 cm can be achieved. UWB positioning, such as RedLore’s High-Resolution Technology, is based on TOF.
- Chirp Spread Spectrum (CSS) is a different wireless technology that is sometimes used as an alternative to TOF/UWB. It has the advantage that the wireless range is typically larger than with UWB, meaning that Anchors can be spaced further apart. On the other hand, the positioning accuracy of Chirp Spread Spectrum is typically only around 2m, making it unsuitable for many use cases where UWB is used. In addition, CSS operates in the already crowded 2.4GHz frequency band, making it more prone to interference.
RTLS Technology Comparison
Ultra-Wideband (UWB)
Ultra-Wideband (UWB) is a technology component built into the RedLore solution that allows estimating the distance between Anchors and Tags with an accuracy of 30 cm (1’). This in turn enables the Positioning Engine to determine the precise location of Tags and the assets they are attached to, as described above [1].
To estimate the distance, wireless signal travel from the Tag is received by the Anchor. Sometimes the term two-way ranging (TWR) is used to mean UWB, but technically TWR is one of the algorithms for UWB to determine the distance between anchor and tag.
The UWB Alliance is an organization for the standardization of UWB technology. As an international organization, they encourage members to comply with the standard.
Bluetooth Low Energy (BLE)
Bluetooth Low Energy (BLE) is a consumer electronics technology that allows Bluetooth beacons and other devices to talk to other Bluetooth devices in a very low-power way. Although very useful and successful in consumer applications, RedLore does not use BLE as tags interfere with other tags, and other Bluetooth and Wi-Fi devices, it is inherently fault-prone. Instead, RedLore uses Wirepas as a wireless mesh data communication technology [2].
WIREPAS
WIREPAS is a wireless data communication technology that is used by all RedLore devices, both Anchors and Tags. WIREPAS is a mesh technology, thus allowing coverage over vast areas without requiring wired base stations: a message hops from one device to the next in a daisy chain until the message finds its way to a gateway and then onto the cloud. WIREPAS smart devices can act as routers for other WIREPAS devices. In WIREPAS, devices are routers AND low-power at the same time, which is not possible with Bluetooth. As a result cabling infrastructure is a thing of the past, thereby saving 85% in total cost of installation.
WIREPAS low-power wireless mesh is one of the two ingredients of RedLore’s wire-free RTLS solution. The other part is RedLore’s patented low-power, high accuracy UWB positioning system. Together, they offer a unique and entirely wire-free experience.
Wi-Fi
Wi-Fi is the wireless communication system we all know and love, primarily used to connect computers to the internet. Some technologies can give some good outputs while using Wi-Fi as a positioning technology [3].
Wi-Fi used to be a common method for attempting to build an RTLS. Although useful in some use cases its lack of accuracy, typically not better than 5 to 10 m (16 to 33ft), makes it unsuitable for most use cases and should be considered a technology of the past. The underlying reason for the lack of accuracy is that in a Wi-Fi positioning system, the received signal strength indicator (RSSI) is used to estimate the distance between the anchor and the tag.
This signal strength indicator becomes very noisy as soon as walls, people or any types of materials obstruct the line-of-sight between the anchor and the tag. In real-life settings, Wi-Fi based positioning systems are rarely successful in achieving room level accuracy.
Infrared Radiation
Infrared is simply light at a frequency (color) that humans cannot see. It has been used for some very specific cases of RTLS, but is no longer considered for new installations.
Infrared technology relies on an infrared transmitter, typically part of the Tag, and an infrared receiver as part of the Anchor. The Tag transmits infrared pulses in a narrow direction, exactly like pointing an infrared remote control to a TV. If the Anchor receives the infrared signal, then the Tag is assumed to be close. If not, then the Tag is assumed to be further away. The infrared pulse can be constructed as a sequence of shorter and longer pulses to carry information within the signal, such as the unique identifier of the Tag.
The RTLS applications of infrared technology are limited to use cases where the tag is close to the Anchor and can be oriented in such a way that is always pointing at the Anchor. In addition, the location can only be determined when the Tag is close to the Anchor and not in the space between Anchors. This is very different from other RTLS technologies, where a Tag’s position can be determined anywhere in the facility and not just close to the Anchor, regardless of the orientation of the Tag towards the Anchor.
Therefore, it is expected infrared technology will fade out of use for RTLS applications.
Ultrasound Radiation
Using ultrasound radiation for RTLS applications is an experimental technology. Just like with wireless time-of-flight (TOF), RTLS as used in Ultra-Wideband (UWB), is measured in the time a message travels between an Anchor and a Tag, by then taking into consideration the speed of sound the distance can be estimated [4].
Ultrasound RTLS may hold some promise for the future as a rival to TOF/UWB. But because of concerns over interference from ultrasound noise in the work environment and errors introduced through reflections (literally sound echos), Ultrasound is typically only considered for proof-of-concepts and has yet to prove it will ever become mainstream.
Passive RFID
Passive RFID or often simply called RFID is a 35-year-old technology that can act as a valuable replacement for barcodes. It replaces the need for a scanner to have a direct optical path to a well-oriented barcode. For the identification of RFID tags, the orientation with regard to the RFID reader can be random and there needn’t be a direct optical path.
RFID has had a lot of success in some industries like clothing retail because the tags are cheap and they can set off an alarm when the tag passes through RFID reader gates at the store exit. They are cheap because they do not need a battery and almost never have any sensors or processing power on board. RFID readers, in contrast, are relatively expensive and need mains power to function.
RFID is only intended for radio frequency identification applications. It is not a suitable technology for the applications targeted by RTLS because the tags are only visible when they pass a few meters/feet from an RFID reader, and almost never have sensors to monitor asset conditions. Unfortunately, we meet customers who tried RFID for solving an incompatible use case and turned to RTLS only after spending a lot of money and time.
Active RFID
Global Positioning System (GPS)
Global Positioning System (GPS) is a system invented and operated by the United States to determine one’s position on the face of the earth. GPS works through an array of satellites around the earth that beam down a signal to terrestrial receivers, such as a smartphone or a plane’s GPS receiver. To receive a reliable GPS signal from a satellite, a clear view of the sky is required, so GPS is not useful in buildings.
After GPS was launched, other countries launched similar systems, such as the Russian GLONASS, European Galileo and Chinese Beidou. GPS can sometimes be used instead of an outdoor (but not indoor) RTLS solution, but only for applications where the position needs to be determined very rarely, such as daily, because the power consumption is much higher than RTLS.
Computer Vision Processing
Computer Vision Processing is sometimes used in specialized application to determine an object’s position. The accuracy can be higher than with RTLS, such as required by a robotic positioning system and surgical systems. On the other hand, Computer Vision requires a careful manual setup of the camera system and is very expensive. As a result, Computer Vision usually has a limited overlap with the target applications of RTLS [5].
Frequently Asked Questions
Which Are the Best RTLS Solutions?
RTLS companies usually optimize for the following qualities: (a) a high positioning accuracy, ideally powered by UWB (Ultra-Wide Band), (b) wire-free, ideally powered by a WIREPAS low-power mesh network, and (c) has tags with onboard sensors for condition monitoring and process automation [6].
RedLore is the only RTLS company marrying all three qualities. It is the only solution capable of providing UWB with battery-powered anchors, saving 85% in installation cost and 90% in installation time.
What Is the Difference Between RTLS and RFID?
RTLS and RFID target very different applications, with nearly no overlap.
RFID, short for Radio Frequency Identification, is the right technology to tag low-value goods that follow a single and well controlled path, such as apparel in a clothing store that goes from the rack to the cash register to the exit, or like a box in a factory flowing on a conveyor belt. At each point where the tag needs to be recognized an RFID reader needs to be installed with a relatively unobstructed view to the tag.
RTLS, on the other hand, is the right technology to provide real-time tracking of tags without the need for proximity to a local reader. In addition, RTLS tags and anchors have onboard sensors that can alert users to impacts, falls, tilt, vibration, temperature and much more.
Does a Central RTLS Require an On-Site Server?
Some RTLS systems require an on-site server to run the Location Engine and the Control Tower (see further down) [7]. Other systems run entirely in the cloud, not requiring an on-site server. In a cloud-based system the data from the Tags and Anchors is sent to the cloud through one or more gateways, usually through a cellular (4G/LTE, 5G) connection.
Cloud-based RTLS systems are superior to on-site server-based systems: They don’t need to touch the local IT system, they are easier to deploy and maintain because there is no server maintenance, and the RTLS vendor is usually faster with updates because an update only needs to be deployed once to the cloud rather than to all on-site servers, which cannot be guaranteed to be online or accessible to the RTLS vendor at all times.
RedLore’s Control Tower and Location Engine software runs in the cloud.
What Are the Main Costs of an RTLS Deployment?
In most RTLS solutions the cabling activity takes 85% of the budget, for planning out the network, bringing in the scissor lifts, paying skilled electricians for the copper wiring, wiring up the electrical cabinet or POE router, etc. The actual RTLS hardware installation is only 15% of the installation cost.
The hidden cost of halting the ongoing operations to make room for the cabling operations and the loss of revenue associated can be multiple times higher than the actual cabling cost.
As RedLore RTLS is entirely wire-free, there is no cabling involved, thus saving 85% of the out-of-pocket cost and avoiding any loss of revenues.
References
- X. Lu, Z. Liu, Y. Wang, and J. Zhao, “A Real-Time Location System Based on Ultra-Wideband Technology for Indoor Environment,” 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC), Chongqing, China, 2018, pp. 1167-1171, doi: 10.1109/ICIVC.2018.8492915.
- Saeedi, S., Shafie-khah, M., Moeini-Aghtaie, M., & Mohammadi-Ivatloo, B. (2018). Location-based tracking of mobile devices using Bluetooth Low Energy (BLE) beacons in an indoor environment. Sustainable Cities and Society, 38, 363-371.
- Mirizzi, F., & Tortorella, F. (2017). Wi-Fi fingerprinting-based localization: A survey. IEEE Communications Surveys & Tutorials, 19(2), 1327-1346.
- Alavi, S. E., Jabbarzadeh, A., & Alinaghizadeh, M. (2014). A new hybrid indoor positioning system based on integrating RFID and ultrasound technologies. Journal of Applied Research and Technology, 12(3), 504-511.
- Alavi, S. E., Jabbarzadeh, A., & Alinaghizadeh, M. (2014). A new hybrid indoor positioning system based on integrating RFID and ultrasound technologies. Journal of Applied Research and Technology, 12(3), 504-511.
- Grzegorzek, M., & Wachowiak, M. P. (2017). Recent developments in visual object tracking. Computer Science Review, 24, 48-69.
- J. M. Keung and S. H. Chan, “Design and implementation of a real-time location system,” 2008 IEEE International Conference on Industrial Engineering and Engineering Management, Singapore, 2008, pp. 1576-1580, doi: 10.1109/IEEM.2008.4738207.
