NovAtel on Satellite positioning

NovAtel are a series-sponsor for Self Driving Track Days and will be presenting in the afternoon workshop session of Introduction to self-driving car technologies (positioning, software and processing).

In the last few days before the event, we talked to Andreas Niemann, NovAtel’s Business Development Manager, based in Germany – about positioning technology for autonomous vehicles, and what changes are expected in the future.

Satellite-based navigation has been a useful tool for consumers for 20 years, how will that change in the next 20 years? 

Although current tools may be sufficient for consumer applications that are not safety critical, this is not a tool that can be used ‘as is’ for applications like (conditionally) autonomous cars or other unmanned vehicles.

Accuracy levels required for applications such as military vehicles, ships, agriculture or in the offshore oil industry already since the beginning of GPS more than 20 years ago, must be adopted for safety critical functions for cars within the next generations of car lines. NovAtel has been a pioneer in positioning for the mentioned non-consumer markets since the beginning.

The biggest differences for future satellite-based navigation systems to today’s navigation devices performance will be in the availability of positioning (always available) and in the integrity of positioning (always trustable). It will become a system that is crucial for safety-of-life applications.

GPS signals are prone to atmospheric interference, problems in urban environments and even bad weather – how can you counter-act these?

NovAtel, being part of the Hexagon group, is able to utilize our group-owned correction services for satellite-based positioning. They can compensate and correct the known issues: clock differences between satellites and receivers, satellite orbit deviations and errors caused by the ionosphere.

For example, customers can access to the global Terrastar PPP service (Precise Point Positioning by Hexagon) with NovAtel receivers either through a certain satellite constellation or through cellular internet connection. Correction performance will be continuously improved by investing in further ground stations and continuous R&D. Already today, cm-level accuracy is possible to achieve, even under non-ideal reception situations.

NovAtel is a leader in designing multi-constellation multi-frequency receivers – not only GPS (USA), but GLONASS (Russia), Beidou (China) and Gallileo (Europe) – that greatly improve availability and accuracy of the positioning performance and reduction of outages.

Another great step will be achieved for example in cars by utilizing inertial sensors or simply sensors that are installed in cars anyway (wheel, steering etc.) to optimize the output. The performance of that kind of positioning will be incomparably better than all systems that are available today in consumer type devices.

What are the drawbacks of these techniques?

The backbone of the techniques mentioned is already existing:

Correction networks are running, more satellite constellations will be added and go into operation mode. Positioning algorithms have been developed to improve positioning continuously. NovAtel has a further roadmap to improve algorithms further.

This will take more time and continuous improvement and requires close cooperation with the end customer, the car maker and/or system integrators.

We expect the positioning system to become more customer specific i.e. for autonomous cars as the car behaviour (delivered by sensors installed in the car) will be an input for the navigation system itself. It will take a lot of development effort on both sides, at the car maker as well as the GNSS system provider, but we know that the awareness and understanding has been built.

Precision GPS equipment is really expensive – If organisations like startups and universities need hardware to develop a new product, what support is available?

We are opening channels to work with Universities and customers at the same time to maximise the efficiency of such cooperation, i.e. in 3-party agreements. NovAtel works actively together with Universities, such as Stanford, and has established relationships with a large number of startups and we are supporting them in their R&D work.

It is not all about providing equipment to customers, universities or startups, the key of success is understanding their intention and then decide together what the best technical and commercial approach is to achieve the target. Our partners trust NovAtel to propose the best solution short and long term.

Can’t they just use their smartphone with the accelerometer?

Smartphones are receiving satellite signals on a single frequency without any of the corrections mentioned above. That is accurate-enough for a lot of consumer type of application (i.e. simple navigation from A to B or tracking sports activities) but not accurate enough to deliver precise positioning results under different conditions (open sky, urban environment etc).

Ideally they could deliver metre-level accuracy but not as often as required for high-precision and safety-critical applications, hence, they are not reliable.

Speaking of smartphones, why does my smartphone get hot when I’m using the maps – and is this also a problem that affects precision-grade GPS systems?

Navigation/Positioning is a hardware and software feature of smartphones, which requires computing power within the GPS/GNSS receiver of the smartphone and also by the central processor of the smartphone. Same as with any other computer the device gets warm indicating significant computing activity.

That’s normal and no problem for any system running within specified limits at all.

In battery powered portable devices it will just discharge the battery faster than without using GPS/GNSS and requires earlier recharging.

The electronic content of cars has grown a lot in the past and will grow significantly.  The power consumption caused by electronic systems in general will increase but high-precision GPS/GNSS alone represents only a very small fraction of that.

The next generation of satellite navigation systems will include what features to make them more accurate?

NovAtel’s R&D efforts on positioning accuracy balance cost, speed and accuracy.

Similar as the answer to the question what will happen in the next 20 years, features such as multi-constellation (not only receiving the positioning signals from the US’ GPS satellite constellation, but also from the Russian GLONASS, the European Galileo, the Chinese BEIDOU or other future constellations) will increase availability.

Multifrequency reception will increase accuracy which will be supported by further software optimization. Other things such a as sensor fusion of various external signals such as inertial sensors, wheel sensors etc will be limited to applications where this is absolutely needed as it will also increase the system cost. Sensor fusion algorithms will also achieve a yet to be determined increase in positioning reliability.

For automotive, compliance to ISO26262 (Road Vehicles – Functional safety) is mandatory and will develop the GPS/GNSS feature into application that are safety (of life) critical. In that case it is important that the positioning is not only precise but absolutely trustworthy. Methods to enable that are currently been researched.

What are the biggest priorities with GPS research and product development right now?

  • Development of hardware and software-algorithms to make them compliant with ISO26262 for automotive safety and integrity.
  • Sensor-fusion to provide a consistent and reliable position.
  • Instant availability of global correction services (i.e. PPP)

 


The company is one of the leading developers of new positioning technologies, and have published An Introduction to GNSS, a free eBook, to help improve understanding of the technology.  [Andreas kindly responded to our questions in his second language, we have edited lightly for clarity.]