High-precision positioning promises mass market automated navigation

High-precision positioning promises mass market automated navigation

Technology News |
By Rich Pell

High precision GNSS solutions have been around for well over a decade, primarily serving high value niche markets. Yet they are ill-suited to meet heightened demands posed by the current wave of technological innovation, of which autonomous vehicles are but one example. For one, their high cost, size, and weight make them unattractive for many mass market applications. More importantly still, they do not scale – a deathblow for a technology that as soon as a few years from now could be standard-issue in new cars.

Now, we are seeing next-generation GNSS hardware and correction services slowly start to overcome these barriers, bringing smaller, more affordable, and fully scalable high precision GNSS solutions to the mass market.

To benefit from today’s high precision GNSS services, positioning devices are required to send their approximate location to a correction service provider. By monitoring GNSS errors – primarily those induced by the ionosphere – using a network of GNSS reference stations, the service provider is then able to provide each of its customers’ correction data tailored to their application’s specific location.

Surveying and, more recently, machine control and agricultural applications, have benefited from centimeter-resolution positioning services for an annual subscription fee of around $600 – $1000 per GNSS receiver. 

In addition to their high cost, these services often operate within a single country, sometimes even within a single state. While that may be well and good for a sedentary farmer, it’s a potential headache for other end users. Imagine driving across a national or state border with a connected vehicle or taking a UAV-based aerial surveying mandate abroad and having to deal with roaming contracts or additional costs to continue to benefit from high precision GNSS services at the new location.

Which brings us to scalability. Conventional high precision GNSS services use two-way communication over the cellular network to pass messages between the user’s application and the correction service provider. Keeping this up when thousands, or potentially millions, of devices are competing for bandwidth with other cellular data requests will make it difficult, if not impossible, to offer reliable access to the correction service. In particular, for safety critical applications, where loss of the correction service translates to less safety for users, this must be avoided.

We are right in the middle of a paradigm shift in high precision GNSS, as a new type of GNSS correction service is beginning to overcome these barriers, in part by doing away with the need for two-way communication between themselves and the end-users’ devices. Rather than sending each device location-specific information on GNSS errors, these new service providers continuously model all of the relevant errors for an entire geographical territory and broadcast this information via the internet or satellite. State Space Representation (SSR)-based technology is an example of this new school of GNSS correction services.

This changes the thinking of the entire industry. Broadcasting the modeled error data to GNSS receivers region-wide, rather than sustaining two-way communication with each one individually, paves the way for high volume mass market applications. At the same time, it undermines the business model of costly subscription-based services.

Figure 1: Observation state representation correction data requires two-way communication to enable high precision positioning, which complicates scale-up.
Figure 2: Broadcasting GNSS correction data with the State Space Representation enables high precision GNSS applications for the mass market.

Japan has been leading the way in broadcasting information on GNSS errors nationwide via the QZSS satellite over the L6 signal, serving as a testbed for mass market applications. While geographically restricted to Japanese territory, the Centimeter Level Augmentation Service (CLAS) is already spawning a lot of interest for high precision applications in Japan, including in precision agriculture, machine control, and autonomous driving. In September 2017, Mitsubishi Electric announced that it was field testing its autonomous driving system using the CLAS service.

In China, QXWZ is adopting an alternative approach to high precision GNSS services. Rather than relying on broadcasting, QXWZ is using its privileged access to Chinese GNSS reference stations to push the limits of the standard approach, offering customers on Chinese territory tailored correction services not only to individual end users but also to OEMs and system integrators. Despite its success in China, this solution is unattractive to OEMs who ship globally as it forces their customers to locally source their GNSS correction services.

As another recent development, we are just now starting to see an influx of multiband GNSS receivers. These may improve user experience in numerous commercial applications by providing improved standalone GNSS positioning accuracy. That said, standalone multiband GNSS receivers will not be able to provide the centimeter-level accuracy required for highly automated vehicles and mobile robotics, which will always require a correction service.

Continent-wide GNSS correction services would benefit customers and service providers alike by simplifying use and servicing large markets. This is particularly true in Europe, where cross-border mobility and economic activity are high. European-based Sapcorda, a recent joint venture between u-blox, Bosch, Geo++, and Mitsubishi Electric, is building a next-generation GNSS correction service for Europe and the US based on the Japanese experience. But instead of relying on satellite communication, Sapcorda will broadcast its correction data continent-wide via the cellular network.

Rather than locking users into a single GNSS manufacturer, Sapcorda will make its correction data available over the internet in an open format, allowing all hardware manufacturers to develop their own high precision GNSS solutions. This approach will be a boon to the industry, as continent-wide access to correction services will take them from a niche service today to a mass market service in the future, serving autonomous and semi-autonomous vehicles, surveying drones, and wide-ranging applications in the Internet of Things.

It’s still early days for high precision GNSS correction services, and there are various technologies and business models vying for dominance. Rather than offering end users GNSS correction services in an open format, US-based Trimble’s service, for instance, works only for devices that use their own GNSS receivers. By offering seamlessly integrated solutions, Trimble can ensure interoperability across their product line – at least in regions where they have good coverage. OEMs selling to geographically diverse markets will, however, be inclined to give up these benefits in exchange for the global coverage offered by a plurality of providers using open correction data.

Figure 3: High precision GNSS enables wide-ranging applications including drone delivery.

In safety-critical applications such as autonomous driving, or where accuracy is central to the entire value proposition such as drone-based surveying, the robustness of a service in non-negotiable. To ensure that broadcasts are not crowded out when cellular networks saturate, u‑blox has been actively engaging with the 3GPP body to develop standards for delivery mechanisms to ensure that service level agreements can be met.

While Japan and China have rolled out country-wide coverage, no one has yet tried to expand coverage of its high precision services across an entire continent or even the globe. If successful, Sapcorda will be the first to overcome the obstacles posed by national borders and country-based mobile service providers. How today’s service providers will adapt remains to be seen.

To be truly successful in mass market applications, high precision GPS service providers will not only have to deliver extensive coverage and openness; their success will depend also on their ability to drive innovation and move out of existing niches to achieve larger volumes. End-customer satisfaction will be paramount for the technology to be taken up by society at large. If, for instance, national and state borders, subscriptions, or conflicting regulations pose a challenge, they are challenges that will have to be resolved upstream of the end user. This is already being addressed by B2B business models in which, for example, device manufacturers work closely with correction service providers to bundle the cost of the service right into the cost of the end-device.

The new generation of high precision GNSS services will be an enabling force for automated navigation solutions that are currently in the pipeline. At the same time, they are dramatically shifting the tectonic plates underlying the entire industry. At u-blox, we are committed to developing the ecosystem by promoting the availability of open and reliable mass market high precision GNSS services through our stake in Sapcorda. And as a provider of mass market GNSS and connectivity hardware, we are also engaged in reducing the cost of ownership technology.

About the author:

Peter Fairhurst is Product Line Manager, Product Center Positioning, u-blox Holding AG.

He joined the Product Strategy team in the Product Center Positioning at u-blox AG in 2015. He is responsible for the development of industrial markets, with a specific focus on unmanned systems and mapping solutions.  Prior to u-blox, he was part of the Product Management group at Leica Geosystems AG, where his focus was on High Precision GNSS Surveying technology.

Peter holds a bachelor degree in Mathematics & Computer Sciences and doctorate degree in satellite geodesy from Newcastle University and an MBA diploma from the University of Strathclyde.

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