Sub-meter Location Tracking and Why It Matters to Automotive and Transportation

Creative and practical applications for wireless distance and location measurement are proliferating.

Wireless technology for location and distance measurement isn’t usually something considered in connection with automobiles. After all, the distances in automobiles are small and do not generally have to be measured carefully. But in recent months the use of UWB radio technology to improve automobile security, as well as the number of automotive innovations that can use and benefit from wireless distance and location measurement have multiplied.

Figure 1. Ultra-WideBand (UWB) technology could have a role to play in making sure that a vehicle meant to stay within a certain distance of a “supervisor” keeps within that distance. Courtesy Wikimedia Commons.

As I discussed in an earlier article, UWB, or Ultra-Wideband, is a radio technology for wireless communication that enables distance to be measured very precisely. That article discussed the use of UWB radio technology to improve automobile security by ensuring that the car owner was indeed standing next to the vehicle when unlocking the door. In the months since its appearance the number of automotive innovations that can use and benefit from wireless distance and location measurement has multiplied.

Most common wireless technologies, such as Wi-Fi and Bluetooth, can be used to measure the distance between two radio units such as on the car and key fob, but will have errors of up to eight meters. Location errors of eight meters might not bother you if you’re calculating which coffee shop a mall shopper is in, but for guaranteeing that a car owner is right next to a car, eight meter errors is too much. The reason for this error is that narrowband radio such as Wi-Fi and Bluetooth suffer heavily from interference, reflections, refractions and other radio artifacts, all of which causes inaccuracies. UWB is designed in a way that overcomes these problems and delivers distance measurements that are accurate to within 10cm, accurate enough for the most demanding automotive applications.
Keeping Cars Under Close Supervision

Keeping Cars Under Close Supervision
The ongoing race towards self-driving cars is one reason distance and location measurement matters in automobiles. While a lot of media attention has looked at the flashy fully autonomous vehicles being developed, a considerable amount of quieter R&D has gone into simpler versions of this. One example is self-parking cars, which cannot drive themselves on busy roads, but are capable of parking themselves in a parking lot or at the curb. Another example is a vehicle that can cruise down a street slowly, keeping its position right next to a mail delivery or newspaper delivery person walking alongside the road (Figure 1).

In both of these cases, even while technologies are being tested in R&D, lawmakers are in action limiting the scope of the technology’s use, in order to ensure safety. Under most laws under consideration, autonomous or semi-autonomous cars will need to ensure that they only move when they are being supervised by a person. This generally means having a person in the car.

Suppose a self-parking or self-cruising car can guarantee that a person with a controller is, say, within two meters of the car as the car is operating? The system would have to be able to measure the distance precisely, to be sure that the car is not driving away from the user or about to run over the user as a radio glitch makes the person appear to be closer or farther than expected from the car. With precise distance measurement provided by UWB technology, the car’s proximity to the person can be guaranteed.

The Fleet Management Challenge
As a second example of automotive applications of location measurement technology, consider fleet management, such as bus depot or car rental parking lots. The manager of such lots needs not only to find each vehicle when it is wanted, but also to manage the workflow of people assigned to clean, maintain and prepare the vehicles for use. Having a precise map of where the vehicles are in the lot can make this much more efficient. Because industrial lots are indoors or covered, GPS will not work. In an industrial setting, several meters of error in location tracking can mean confusing cars that are in the cleaning process and cars that are waiting for repairs. Not only will this impact the performance of the workers as they spend more time finding the car or bus they are looking for, but it will also make impossible the implementation of advanced analytics systems, which are a key element to achieve the aggressive operational efficiency goals requires in these industries.
UWB, thanks to its level of accuracy, now offers the possibility to track the positions of the cars and busses in the lots, as well as tracking the locations of staff and tools as they move around the lot.

Figure 2. The management of large numbers of vehicles at bus depots, for example, is an application for location measurement technology. Courtesy Wikimedia Commons.

UWB can be used to track each vehicle’s location precisely within such an indoor parking structure. Locator units installed every 50-100 meters along the walls can use the same UWB radio mentioned above to track the locations of vehicles within the lot. This is done using a process called “trilateration,” basically measuring the distance that each vehicle is from three or more locator units, and calculating the location in the lot that is the required distance from the locators. Other technologies, such as Bluetooth, can do this as well, but with inaccuracies of five or more meters, which can lead to confusion between vehicles parked near each other.

Reducing Error to Less than a Meter
As a third example, consider the growing number of consumer devices that cannot be used by drivers while driving, but which can be used by passengers in a vehicle. Many GPS applications already ask device users to confirm that they are passengers and not drivers, but of course the device cannot be sure that the question is being answered truthfully. With precise location technology inside the car, a device can ensure that it is not used by the person sitting in the driver’s seat. As in the examples above, this can only be done with technology such as UWB that can measure location to within 10cm and not have errors of over a meter.

As a fourth example, many people have been frustrated when they are using their phone near a running car, but outside of the car, and have their calls routed to their Bluetooth-based hands free units. These hands free units cannot distinguish between a phone user inside the car and a phone user that steps out of the car for a few minutes and wants to take his calls privately. But UWB can track locations accurately enough to determine when the phone is taken out of the car.

All of these examples of automotive use of wireless location technology have a key element in common: they all require that the location measurement be highly accurate. Many smartphone-based location technologies, including those based on Wi-Fi and Bluetooth, are typically inaccurate by over five meters. But newer technologies are reducing the error to less than a meter. UWB is a key technology in this area, with error rates around 10cm.

This is a trend with impact beyond the automotive industry. Both ABI Research and Grizzly Analytics have identified sub-meter accuracy location technologies as a key focus in the future of location technology. UWB is currently leading the market in sub-meter location tracking, with other technologies working to close the accuracy gap. Solutions now on the market make UWB is available in a single-chip low-power implementation.

We’re seeing next-generation automotive technologies, such as self-driving and self-parking cars, in-lot vehicle tracking, in-car driver/pedestrian differentiation, and more, go from research to development to market. As they do, component technologies such as UWB can enable the precise location tracking that is needed to ensure safety and compliance. On the horizon are additional exciting automotive and transportation developments that can be supported once location can be tracked accurately.

Viot_headshotMickael Viot is Marketing Manager at DecaWave, a fabless semiconductor company headquartered in Dublin, Ireland.

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