back to article Spanish boffins increase GPS accuracy by 90%

Boffins at Madrid's Carlos III University have used cheap accelerometers and gyroscopes - and expensive mathematics - to improve the accuracy of GPS* by as much as 90 per cent. The team compared their results to differential GPS - which is about as good as satellite systems get - and found that with detailed analysis of the …

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  1. GettinSadda
    Boffin

    GPS for Dummies

    Do we really need an explanation of what GPS is... in an article in The Register?

    1. GBL Initialiser
      Boffin

      Re: GPS for Dummies

      There is no harm in it. Those that don't know how it works benefit from it and learn something. Those that do know how it works ignore it or come to the comments section to make sure everyone knows that they know, ya know?

      1. Adam Trickett
        Boffin

        Re: GPS for Dummies

        Perhaps it's for Stephen Fry...?

        1. Anonymous Coward
          Anonymous Coward

          Re: GPS for Dummies

          You do know that Stephen Fry is a gadget head? he has about 4 smartphones, one from each platform.

          He had one of the first Apple Macs in the UK too, along with Douglas Adams.

          I'm sure he's perfectly aware of what GPS is.

          1. Richie Hindle
            FAIL

            Re: GPS for Dummies

            You might be sure, but you'd be wrong: "You send a signal from your GPS device..." http://www.theregister.co.uk/2011/01/18/stephen_frytard/

          2. Gordon861

            Re: GPS for Dummies

            Look on YouTube for Stephen Fry explaining GPS on QI, I think you will find he doesn't.

          3. Vic

            Re: GPS for Dummies

            > I'm sure he's perfectly aware of what GPS is.

            ...But no idea how it works :-(

            Vic.

    2. Anonymous Coward
      Anonymous Coward

      Re: GPS for Dummies

      "Do we really need an explanation of what GPS is... in an article in The Register?"

      As a brainbox on GPS, then, you can help me out with a little conundrum. If the cheapy GPS receivers in a mobile phone are only accurate to 10m, how does it (usually reliably) know which lane I'm in, given that would require circa 1-2m accuracy to give lane guidance to an acceptable degree?

      1. Andrew Moore Silver badge

        Re: GPS for Dummies

        Because the normal accuracy is usually around 1-2 meters in decent conditions. However 10 meter inaccuracies are not unusual and are dependent on how many satellites are in view and whereabouts in the sky they are. There are other factors too, such as ionospheric and tropospheric error and even if the satellite is in the right place and broadcasting the correct time.

      2. Anonymous Coward
        Anonymous Coward

        Re: GPS for Dummies

        It presumes you're going in the right direction on the correct road and works it out using last know speed. Easy to test, hook onto a slip road you not supposed to do, then see how long it takes to notice that you are not where you are supposed to be. You could slam on the brakes and do a u-turn and again see how accurate it is, but probably not the best on the M1.

      3. Spider

        Re: GPS for Dummies

        direction of travel usually. calculated by sampling a preset duration of position previous to determine velocity

      4. Annihilator
        Boffin

        Re: GPS for Dummies

        "If the cheapy GPS receivers in a mobile phone are only accurate to 10m, how does it (usually reliably) know which lane I'm in"

        Sorry, which GPS is actually giving you an indication of which *lane* you're in? It might know "northbound" vs "southbound" or similar (which is carriageway information, not lane) but it knows that purely from your actual direction. Sat navs "snap-to" roads, allowing them to be very accurate. Try coming off a road onto a farm track and watch it lose its way quite quickly.

        Even when not snapping-to a known location where it expects you to be (roads), it can use fuzzy logic to determine where you are, as the 10m accuracy will vary over time, and a GPS knows that you'll roughly travel quite consistently. If your reading jumps from 5m side to side, it's more likely the error has varied rather than you've moved erratically.

        1. An0n C0w4rd

          Re: GPS for Dummies

          Sorry, which GPS is actually giving you an indication of which *lane* you're in? It might know "northbound" vs "southbound" or similar (which is carriageway information, not lane) but it knows that purely from your actual direction. Sat navs "snap-to" roads, allowing them to be very accurate. Try coming off a road onto a farm track and watch it lose its way quite quickly.

          Even better, if it tells you to take a slip road off the motorway, and you don't, it'll take quite a while to figure out. It assumes that you are following it's instructions until you exceed the "snap-to" failure threshold. Normally it takes my car until I pass the roundabout at the end of the slip road before it figures out that I've ignored it's advice because near to home I know the roads better than it does (most sat-navs don't figure traffic lights into time calculations, so while the way it sends me is shorter, it takes longer because of the stop-start traffic. So I go the long way because there are no traffic lights. Usually get home sooner)

          Of course, if you wanted to get real accuracy you'd use the encrypted GPS signal only (officially) available to the military. I forget what the accuracy is, but it's sub 1 metre from memory.

          1. Nick Ryan Silver badge

            Re: GPS for Dummies

            I'd just be happy if the damn things gave me an indication of what direction they think I should take on the roundabout at the top of a slip road before I get to the ****ing roundabout itself.

            I've made more navigational mistakes following sat navs than not. They're very useful but I also like to know where I'm going without them.

        2. Vic

          Re: GPS for Dummies

          > which GPS is actually giving you an indication of which *lane* you're in?

          Not quite a *lane* as such...

          I use a bike computer[1] to track my flights. It doesn't snap to anything, because it's expecting you to be off-road (which is why it's useful).

          It shows the track of my landings in a remarkably similar place to where I did them. Now the runway is wider[2] than a motorway lane, for sure, but the accuracy still appears to be somewhere near enough to discriminate between lanes...

          Vic.

          [1] It's an Android app called "Move!". I've found it invaluable for keeping a record of where I went and what I did.

          [2] I can't find a reference to how wide it is - I'll ask on Sunday when I'm next there.

    3. Andrew Moore Silver badge

      Re: GPS for Dummies

      You do when you get statements like:

      "The team compared their results to differential GPS - which is about as good as satellite systems get "

      RTK can get the GPS accuracy down to sub-decimeter (less than 10cm).

      1. Anonymous Coward
        Anonymous Coward

        Re: GPS for Dummies

        Sub-decimeter sounds so much more impressive than "a bit less than four inches", doesn't it?

        1. Phil E Succour
          Joke

          Re: GPS for Dummies

          >>Sub-decimeter sounds so much more impressive than "a bit less than four inches", doesn't it?

          I bet you say that to all the girls!

    4. Don Jefe

      Re: GPS for Dummies

      I think it is rather important to differentiate between a satnav device vs a GPS. I teach a ground navigation class once a year a semester at the local uni and I have to explain that while a satnav (generally) uses the GPS system to give directions, a standalone GPS only gives you your current location (unless data has already been put ino the system) and records your current location/path.

      It is an important distinction. If I gave most people my Trimble GPS they would have a hard time getting from point A to B.

      1. Anonymous Coward
        Anonymous Coward

        Re: GPS for Dummies

        Indeed it is important to distinguish between a satellite navigation system and "a GPS", which is a set of satellites orbiting the Earth plus the associated ground-based infrastructure.

  2. Anonymous Coward
    Anonymous Coward

    You do understand that an autonomous car wouldn't rely on GPS for general safety and moving about the road right?

    1. Rikkeh

      Beat me to it- you'd never be able to do it solely off GPS, as unnotified roadworks, obstacles in the road and (snigger) apple maps would mean that knowing where you are on the planet would only get you so far with where on the road you should be.

    2. Anonymous Coward
      Anonymous Coward

      You do understand that an autonomous car wouldn't rely on GPS......

      Really, I never knew that!

      I thought GPS could spot pedestrians walking in the road, avoid ad-hoc road works and alert me to when a red light was on a traffic light.

      Thanks for enlightening me.

      1. GBL Initialiser
        Terminator

        Re: You do understand that an autonomous car wouldn't rely on GPS......

        @AC 14:47

        No, that's the satellite directly to the left. The one with "skynot" or something written on the side, can't make it out from down here.

      2. Nick Ryan Silver badge
        WTF?

        Re: You do understand that an autonomous car wouldn't rely on GPS......

        @AC 14:47 GMT

        No, all those functions are handled by RFID. At least that's what the IBM RFID adverts were implying anyway.

  3. Electric sheep
    Stop

    So

    does the 2 metre accuracy mean it stops just before or just after the STOP sign??

    ;-)

    1. Andy Gates
      Facepalm

      Re: So

      As the author ought to know, close stuff is done by computer vision and lidar and such goodies.

      Even if the maps were perfect and the GPS nanometer-good, you need to check the groundtruth before driving over it. Silly Bill Ray.

      This accuracy is great for lanes, mind.

    2. Eugene Goodrich
      Paris Hilton

      Re: So

      If it stops at all it'll be better than some drivers.

  4. easyk

    Just skimmed the paper

    It looks like they are using a Novatel OEMV which in the configurations I'm familiar with will run you about $6000. An IMU on the from crossbow similar to the one they describe is another $6000. I guess it is better than the $100K systems that some reaserchers strap on their systems but not cheap.

  5. Markus Imhof
    Trollface

    So you're still driving on the wrong side of the road?

    'two meters to the left' wouldn't endanger pedestrians in most countries - only the passengers of the vehicle drifting to the left and those in the oncoming trafic. Two meters to the right, though, would be a different problem.

    1. Robin

      Re: So you're still driving on the wrong side of the road?

      Here's the generic formula for you:

      2 metres to the left/right* = killing pedestrians/colliding with oncoming traffic*

      * Delete as applicable

  6. Anonymous Coward
    Anonymous Coward

    dead reckoning brought up to date then.

    1. Pet Peeve
      Boffin

      It's inertial navigation. Nothing new really.

      I've actually been wondering when car GPSes would start using inertial corrections to improve accuracy. It makes installation a little more complicated, since you have to put the accelerometers and gyros in the right place (likely slightly different for each car), but it would be a great factory feature.

      1. TeeCee Gold badge

        The one built into my car already does it.

        It knows how fast its going (speed sensor) and which direction it's going in (steering angle sensor)[1], both of which are standard on most cars these days. Given a recent fix to start from, what else do you need?

        It's always amusing to watch it trying to match the maneuvers I'm making in an underground car park to the roads above....

        [1] Ok, most of the time. Presumably it wouldn't have a clue what was going on if I were to four-wheel drift it round a corner.....

        1. Vic

          It's always amusing to watch it trying to match the maneuvers I'm making in an underground car park to the roads above.

          You want to see the confusion when you run one in an aircraft :-)

          Vic.

        2. Boothy

          Some Tomtoms already have this, and Android phones.

          On Android it's next to the GPS on/off, called 'Use sensor aiding'. (Not sure if this is OS version or phone type dependent, but it's there on a S3).

          1. Martin Budden

            I'd always assumed that smartphones already did this, as they have the sensors.

          2. Dave Lawton

            Also on the S2

        3. BristolBachelor Gold badge

          "The one built into my car already does it....

          It's always amusing to watch it trying to match the maneuvers I'm making in an underground car park to the roads above....

          Yeah, the one in my TomTom does it too, but only using a built-in accelerometer.

          However sometimes I have to drive into Madrid city, where they have quite a long section of motorway underground, complete with junctions. The TomTom guides you into it, and then half-way through it suddenly decides that you are on the surface, and starts trying to snap your location to the roads up there. Meanwhile, it forgets to tell you which junction you were supposed to take to get out of the tunnels in the right place.

          For me issues like that, and closed/new junctions on the 2nd busiest motorway in Madrid not being updated for >2 years is more of an issue than the inherant location accuracy.

      2. Don Jefe

        The navigation system offered in the mid 90's by Fujitsu Ten under the Eclipse brand used accelerometers and gyros that had to be installed with the rest of the system (display, "magic box", cellular antenna and CD player where you put the map disc you wanted to use). It was complicated as hell, didn't work worth a shit, very expensive and sounded like a "speak and spell" when it spoke.

        I don't think aftermarket sensors are ever going to be truly road worthy. The real advances will come when most/all OEMs offer more accurate systems from the factory.

  7. Anonymous Coward
    Anonymous Coward

    Self driving cars will ultimately fail.

    What is the point when the human will have to sit there and be sober and conscious?

    1. Anonymous Coward
      Anonymous Coward

      You can kill time by Googling for impossible results?

    2. Anonymous Coward
      Anonymous Coward

      Ultimately, you wouldn't need to be sober or conscious.

      1. Martin Budden
        Go

        Bring it on!

        I can't wait for an autonomous car which can drive me home after I've had a few beers. We could also change from being a two-car family to being a one-car family: after the car takes me to work in the morning, it can drive itself back home then take the missus and spawn to their destination.

        1. Nick Ryan Silver badge

          Re: Bring it on!

          That's my dream too. Just because I can drive, doesn't mean that I either like it or want to do it.

          Unfortunately I think such true motoring convenience is at least a couple of decades away.

        2. Anonymous Coward
          Anonymous Coward

          Re: Bring it on!

          We already have them they're called buses, trains and taxis.

          1. Anonymous Coward
            Coffee/keyboard

            Re: Bring it on!

            No they're not. The nearest bus stop is 3/4mi away. Taking that to the train station takes over an hour.

            Unfotunately, in the greater Atlanta area, we have several independent transit authorities and I think they're all run by either 1) idiots and/or 2) crooks.

  8. Robin

    Las Carreteras

    On the roads over here it's normal practice for drivers to have a standard deviation of 2 metres anyway. Roundabouts are a free-for-all.

    1. Dan 55 Silver badge
      Pirate

      Re: Las Carreteras

      Sideways is +/- 2 metres. Forwards/backwards while on the move is precise down to a range of approximately +/- 25cm. Parking is precise down to the nanometre (don't worry, bumpers and number plates are designed to crunch).

      1. Robin

        Re: Las Carreteras

        'tis true. I'd say literally every single car has parking-related damage of some description.

        Although narrow streets densely packed with cars have certainly improved my parallel parking skills (without using the bumpers)

  9. martin 17
    Stop

    GPS technicalities

    "outperforming differential GPS by a significant margin"

    Real-time DGPS will give you centimetre accuracy, how does this system outperform DGPS?

    "drift caused by atmospheric changes"

    Discrepancies due to time sync differences between satellite and receiver clocks, arguably, is equally important, and definitely worth mentioning if you start explaining GPS (also uncertainty in ephemeris, satellite geometry and, being pedantic, general relativity)

    1. The last doughnut
      Happy

      Re: GPS technicalities

      Don't forget to mention that GPS is an American military system and that they can and do program the satellites to deliberately degrade system accuracy. There is also two parts to it - the open code signal that is often quoted as having 10 metres accuracy, and the secret code signal that is more accurate but not generally available to all users.

      I think the Register hack was told to write a description of Differential-GPS in the footnote, but he bottled it.

      1. Malmesbury

        Re: GPS technicalities

        1) The Amerixcan military moved away from degrading the unencrypted signal on GPS years ago. The unencrypted accuracy is the same as the encrypted. The limit is pretty much physics now.

        2) They have actually removed the degradation feature from new satellites added to the constellation - as the older satellites go out of use, this option becomes less and less possible.

        3) The reason the Q code is encrypted is not secrecy. It was assumed when GPS was designed that the Russian equivalent would be up and running rapidly. The Q code is there to make it harder to jam (lock on the signal when jamming is actually louder than the signal - think listening for a known tune) and to make it very, very, very hard to spoof (you would have to know the code to broadcast a fake signal).

        1. The last doughnut
          Unhappy

          Re: GPS technicalities

          I disagree, sir. The secret code version is about ten times more accurate, or at least has the potential to be. They used to boast about being able to put a cruise missile through a window. Also, its not difficult to jam at all.

          You are probably right about them not bothering with selective availability any more.

          But WTF I get three downvotes for an ordnary post like that?

  10. lee harvey osmond

    Patent? prior art?

    I recall driving through the Limehouse Link tunnel and then between some tall buildings along London Wall one day, in 2010 I think, and noticing the loss of satellite signal, and remembering that my then-new iPod Touch could tell which way up I was holding it because of digital accelerometers. I recall mentioning this via email to a TomTom engineer ... "with a couple of orthogonally-arranged accelerometers, you could achieve inertial reference navigation, as a secondary position source when GPS reception keeps dropping out", and the reply I got indicated that this was a newly-introduced feature on top-spec models.

    1. TRT Silver badge

      Re: Patent? prior art?

      It's been a part of the Prius sat-nav since, ooh, about 2003. Inclinometers and gyroscopes which form part of the anti-skid system, augmented further by the high precision axle rotation sensors which the hybrid drive requires (you have to manually calibrate the nav system every now and again to allow for tyre wear which is best done on a long, straight motorway), and a position sensor on the steering shaft, which is part of the electrically-power-assisted steering.

      Still that's all expensive stuff and even then brings the accuracy down to only a metre at best.

    2. GarethB

      Re: Patent? prior art?

      When I was with Roke Manor Research back in 1993 while at uni I was working on a similar system they were developing so its certainly not new

  11. Steve Todd
    Stop

    I'm not sure I'd want to trust ANY system

    That doesn't crosscheck the mapping data it has with the real world around it. The number of times I've seen errors in GPS maps (dedicated and in tablets/mobile phones) doesn't inspire confidence in such a system.

    1. Anonymous Coward
      Anonymous Coward

      Re: I'm not sure I'd want to trust ANY system

      GPS and maps are two different things, that are combined in a Satnav.

  12. Bob H
    Go

    I saw a presentation by the guy from BAE who wrote the system which uses "Signals of Opportunity" (TV/radio transmitters and mobile masts), that is seriously impressive, seriously cheap and self calibrating. This proposal seems to tackle the same problem from a physical environment perspective.

    In respect of the 2m accuracy killing people, I think if autonomous car designers used street maps alone for their navigation it would be very optimistic. Better to use a range of tools, like this one, combined with collision avoidance, road marking recognition, environmental awareness, etc.

    1. John Smith 19 Gold badge
      Go

      "Better to use a range of tools, like this one, combined with collision avoidance, road marking recognition, environmental awareness, etc."

      Yes

      Might it be better to look at not hitting stuff within 2m of the vehicle as "collision avoidance" rather than navigation?

      Different response times, different range.

  13. Andus McCoatover
    Windows

    Gyroscopes on submarines....

    Remember my boss telling me this: A sensor on one of the gyros failed. Decouple it, stick it in a straw-lined box (still spinning) and courier it back to the manufacturer. (Gawd knows how the driver took a corner!)

    They'd get it 2 days later - stil spinning - , change/fix the sensor, spin it back up to full speed again, then return it to the boat. 2 days later, still spinning, fit it back. Bloody thing was still accurate to about a metre....Dunno if he was casting me a line, but...

  14. John H Woods Silver badge
    FAIL

    90%?

    Surely "improving accuracy by 90%" is making it a little less than twice as 'accurate' whatever that means. I'm pretty sure you meant a 10-fold improvement in precision.

  15. Marketing Hack Silver badge
    Stop

    Even two meters would be pretty dangerous in a self-driving car

    I can definitely see two meters resulting in cars pushing into crosswalk areas and pushing over pedestrians, or nosing too far out into an intersection before making a turn and getting the front of the car taken off by a semi...

    Stop sign icon works on a few different levels in this case......

  16. Charles Manning
    Boffin

    Having spent years in the industry...

    I worked for one of the companies doing high accuracy GPS for 12 years.

    With RTK GPS, you can get 20mm - yes folks - less than an inch accuracy and we could control the steering of tractors etc down to better than 150mm (6 inches). With DGPS sub-metre has been possible for many years too.

    These are absolute accuracy, but when you're controlling a vehicle, drift is far more important and you re-reference from other cues.

    Modern self driving vehicles would never use just GPS. Instead GPS is just one of the sensors being "fused" into an effective solution.

  17. just_me
    Boffin

    This was accomplished over 10 years ago

    This is definitely not new. I know of at least one company who did work on this over 10 years ago. There are also many articles about using Inertial (gyro + accelerometer) aided tracking with GPS. One company that I know of is Cubic Defense Applications Inc. Look up "GPS denied tracking" on Google. The inertial devices being used were not high cost/expensive. They were MEMS devices...

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