Thursday, 18 September 2014
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Engineers look to low-cost sensors as GPS backup

British researchers are developing a navigation system that can locate itself by scanning the surrounding environment.

The technology, intended as a backup to satellite navigation systems in road vehicles, will use a variety of low-cost sensors to gather information about its location, such as terrain height, magnetic fields from nearby metal objects and even street signs and road surfaces.

This could give greater security to vehicles currently reliant on global navigation satellite systems (GNSS) such as GPS, which are vulnerable to signal loss and hostile attacks such as jamming with interference.

‘Many technologies rely solely on GPS and are not looking at what happens if for any reason it is not available,’ said Debbie Walters, the PhD student at University College London who is developing the system with industrial partner Terrafix. ‘This would work alongside GPS and be a backup in case anything was to happen.’

Walters is presenting her idea today at a UK conference at the National Physical Laboratory (NPL) on responding to GNSS vulnerabilities. Other alternatives being put forward include wif-fi signal mapping and highly accurate accelerometers that use quantum technology.

The multisensor system would kick in if GNSS signals became unavailable, taking the last known location as a starting point and then working out the current position based on information gathered by the sensors and cross-referenced with a database.

Different sensors could be added to the platform depending on the location and as the technology developed.

Walters’ initial work has involved assessing a variety of sensors including a magnetometer, barometer, accelerometer, video camera and microphone, with the magnetometer and barometer initially proving most consistent in gathering data on magnetic fields and terrain height, respectively.

The next step will be to determine the best way to build the databases that would form the basis of a reference map and how to cross-reference it with the sensor data in real-time. Walters hopes to have a prototype system ready by the middle of next year.

Part of this will involve working out to manage the multiple data streams, as they provide different measurements at different frequencies, and integrate them into a single output.

‘You need to ensure there is no interference between the different sensors and ensure you have the correct measurements,’ said Walters.

‘Understanding the limitations of the sensors means we have to understand how to bring them into the system and get the correct weighting for different types of sensors.’

Prof Brad Parkinson, the chief architect of GPS, is also due to speak at the conference on the importance of further development of GNSS alternatives.

‘Over the years, manufacturers of signal receiver technologies have focused too much on sensitivity and not enough on resilience or robustness,’ he will say.

‘There are a wealth of solutions to toughen and backup GPS, many of which are not technologically difficult nor expensive, but still their adoption in sectors such as global shipping is certainly not adequate.’


Readers' comments (3)

  • Or could consider using something like the eLoran (update of the old hyperbolic Loran system) system being rolled out in the UK.

    Predominantly for shipping as a backup to satellite position it could presumably be modified and calibrated to work across land with a certain level of accuracy.

    Or you could just ask a local the way!

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  • This astounds me slightly, not at the problem so much i.e. jamming / uanavailability of GPS but more the solution.

    Multiple industry areas / technologies have been using Inertial Navigation for decades including maritime, aviation, and sub-marine. As log as you have the starting reference either manually keyed or derived from a source such as GPS, the current position will be available.

    With the reduction in size of gyros from the old mechanical types to the newer Coriolis Vibratory Gyroscope (CVG) types small yet accurate Inertial Navigation systems should be viable, and incidentaly are particularly used in Submarine Remote Operated Vehicles.

    Call me old fashioned, having come through various apprenticeships and in house training schemes but possibly the universities and students should look at improving / enhancing on existing technology before trying to re-invent the wheel, or at the very least appreciation of what came before the current technology.

    Technical issues such as nutation still need to be overcome with IN if distances/times travelled are to be large, albiet with modern computing power this could simply be a correction alogerithm.

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  • I have always relied on GPS as the back up to a map book from the local garage £4.99p.

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