UWB for industrial environments: looking beyond asset tracking
Ultra-wideband technology is unique because it can process contextual information, such as position, movement, and distance between UWB-enabled devices, with the precision of just a few centimeters. Many companies are already leveraging this spatial awareness capability and implementing UWB on manufacturing floors into Real-Time Locating Systems (RTLS). However, there are many more UWB applications for industrial environments beyond asset tracking.
The process of determining the horizontal distance between two points (or devices) is known as ranging. Time-of-Flight (ToF) is a form of ranging that uses signal travel times to calculate distance, see figure 1.
Figure 1: How to calculate Time-of-Flight using UWB [Source: NXP].
Uniquely, UWB uses a series of short pulses (nanoseconds) over a wide frequency band (500 MHz), which allows a pinpoint accuracy to within ±10 cm. On the other hand, other wireless technologies, such as Wi-Fi and Bluetooth Low Energy (BLE), use a modulated sine wave over a narrow frequency, limiting the range to around ±1 m to ±5 m.
ToF calculations determine the radial distance to an object, not its direction, which is why ToF diagrams are depicted as circles, see figure 2: If the ToF calculation reveals that Device 2 is 15 cm away from Device 1, then Device 2 could be anywhere within that radius. To determine the position of Device 2 from Device 1, an additional device would be necessary for triangulation.
Figure 2: Comparison of ranging accuracy between UWB and other wireless technologies, such as Wi-Fi and Bluetooth Low Energy, and localization through a dedicated array of antennas.
An alternative to needing a third device is to use a dedicated array of carefully positioned antennas to calculate the AoA. There is a discernible difference, albeit tiny, in the arrival time and the phase of the returned signal at each antenna. These differences are used in a geometric calculation, similar to triangulation, which determines the direction from where the signal came. Not all UWB solutions include the extra antennas, however, those that do can deliver accuracy to within just a few centimeters.
Knowing where an object is located in real-time is beneficial in many ways. In industrial applications, it can improve item utilization rates and save time spent searching for things. New levels of ‘just in time’ efficiency are possible on the factory floor, as well as for inventory management. Another benefit of determining an accurate location is safety. Keeping track of where people, automated guided vehicles (AGVs), and robots are relative to each other in real-time can help prevent accidents.
Smart door locks for quick but secure access
Security authorizations based on location is another possible use for UWB, as precise, real-time location is hard to fake. A UWB-enabled smart door lock, for example, can detect and identify a person as they approach and automatically unlock, if authorized to enter. This approach speeds up door access by eliminating the time it usually takes for a person to fiddle around to find the correct key, remember the right pin code, tap a card, or take their smartphone out of their pocket. Also, for AGVs, USB-enabled smart door locks enable them to move seamlessly and efficiently from one hall to another. It can automatically relock as the person or AGV moves away from the door. UWB also allows the safe sharing of access credentials, giving personnel or vehicles temporary access to a particular area.
As UWB is more precise than the other wireless technologies, it is a safer and more secure way to provide access control. In particular, UWB is immune to relay attacks. Should attackers succeed in capturing and boosting the UWB signal, the relay is not able to respond to the UWB lock’s acknowledgement signal quickly enough, making it clear that it is farther away.
Taking the guesswork out of Social Distancing
UWB technology is also being utilized in proximity awareness applications, particularly in the manufacturing industry. A purpose-built UWB device that is worn around the neck or wrist, pinned to a shirt, or put into a pocket, can help determine how far a person is from someone else. Should a person wearing a similar device come inside the pre-determined safe-distance ‘bubble’, an alarm signal sounds or vibrates. By reminding people of the social distancing rules in place, employees can keep a safe distance from each other.
Smarter energy management
Contextual decision-making based on accurate, real-time location is another exciting use for UWB. UWB-enabled sensors can respond to the presence of people in a workspace, for example. A typical setup could be turning on the lights as people enter a room and switching them off again as they leave. This type of smart building application can also apply to HVAC control systems, managing the energy consumption better without touching a button or hitting a switch.
While UWB is on the rise to become a well-established localization technology for asset tracking and warehouse optimization, its potential is yet to be exploited for applications designed to increase security and safety on the manufacturing floor. Standardization bodies, such as the FiRa Consortium, are committed to investing in an interoperable UWB eco-system. This holistic approach will help drive the overall awareness of UWB and its multitude of use cases.