Re: [OSM-talk] Motion sensors for navigation
Erik Lundin writes: > That's correct, but the earth's magnetic field is often the dominating. > If a classical compass can point out the earth's magnetic field, why > shouldn't it be possible with an electronic sensor? Quick fluctuations > could be filtered out. Because cars are made of steel which bends the magnetic field? Check the lead of http://en.wikipedia.org/wiki/Gyrocompass -- Było mi bardzo miło. Czwarta pospolita klęska, [...] >Łukasz< Już nie katolicka lecz złodziejska. (c)PP ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Motion sensors for navigation
On Thu, 25 Mar 2010, Erik Lundin wrote: > Talking about tunnel tracking... > > I have thought of a solution were you have a GPS device together with an > electronic compass sensor. In the tunnel, the position is calculated by > knowing the last position, the speed (either from the speedometer in a > car or keeping the same speed as before the tunnel) and the compass > direction. Since the error in this case increases exponentially with > time (right?), it would help to drive through the tunnel in both > directions. > That was my son's method, to do the track from both ends. Yes the errors increase exponentially with time from each time you zero the device. The error was still huge. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Motion sensors for navigation
On 25 March 2010 18:09, Erik Lundin wrote: > That's correct, but the earth's magnetic field is often the dominating. > If a classical compass can point out the earth's magnetic field, why > shouldn't it be possible with an electronic sensor? Quick fluctuations > could be filtered out. Because electronic sensors are surrounded by electromagnetic fields... ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Motion sensors for navigation
That's correct, but the earth's magnetic field is often the dominating. If a classical compass can point out the earth's magnetic field, why shouldn't it be possible with an electronic sensor? Quick fluctuations could be filtered out. /Erik John Smith skrev: > On 25 March 2010 10:20, Erik Lundin wrote: >> I have thought of a solution were you have a GPS device together with an >> electronic compass sensor. In the tunnel, the position is calculated by >> knowing the last position, the speed (either from the speedometer in a >> car or keeping the same speed as before the tunnel) and the compass >> direction. Since the error in this case increases exponentially with >> time (right?), it would help to drive through the tunnel in both directions. > > Magnetometer sensors are sensitive to all sorts of magnetic fields, > not just the magnet field of the earth and so aren't very accurate, to > prove this point someone made a metal detector for android phones a > while back and it really does detect metal, or at least the magnetic > field around metal. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Motion sensors for navigation
On 25 March 2010 10:20, Erik Lundin wrote: > I have thought of a solution were you have a GPS device together with an > electronic compass sensor. In the tunnel, the position is calculated by > knowing the last position, the speed (either from the speedometer in a > car or keeping the same speed as before the tunnel) and the compass > direction. Since the error in this case increases exponentially with > time (right?), it would help to drive through the tunnel in both directions. Magnetometer sensors are sensitive to all sorts of magnetic fields, not just the magnet field of the earth and so aren't very accurate, to prove this point someone made a metal detector for android phones a while back and it really does detect metal, or at least the magnetic field around metal. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Motion sensors for navigation
Talking about tunnel tracking... I have thought of a solution were you have a GPS device together with an electronic compass sensor. In the tunnel, the position is calculated by knowing the last position, the speed (either from the speedometer in a car or keeping the same speed as before the tunnel) and the compass direction. Since the error in this case increases exponentially with time (right?), it would help to drive through the tunnel in both directions. /Erik David Earl skrev: > On 23/03/2010 12:21, John Smith wrote: >> On 23 March 2010 21:56, David Earl wrote: >>> I wonder whether they might be interested in offering us some units for >>> testing? >> Using inertial navigation the accuracy deteriorates considerably over time. >> >> http://en.wikipedia.org/wiki/Inertial_navigation > > Yes, obviously. The problems we have are exactly the ones they are > trying to solve though - urban canyons and tunnels - where we lose the > GPS accuracy for a short while. I don't think they're suggesting they > are a substitute for GPS, just to augment it where GPS can't reach. If > they are looking at military applications, the accuracy has to be an > order of magnitude better than we would need as is their GPS. > > David > > > ___ > talk mailing list > talk@openstreetmap.org > http://lists.openstreetmap.org/listinfo/talk ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Motion sensors for navigation
On Wed, 24 Mar 2010, Richard Weait wrote: > Cool things can be done with MEMS. > > Introduced in December 2002 now scheduled for obsolescence > http://www2.electronicproducts.com/Gyroscope_on_a_chip_is_industrys_first-a > rticle-DECHL3-DEC2002.aspx > > Replaced by > http://www.analog.com/en/sensors/inertial-sensors/adxrs613/products/product > .html at ~$30/each > have a look at Kinetamap http://bit.ly/VJ6jm ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Motion sensors for navigation
On Tue, Mar 23, 2010 at 9:03 AM, John Smith wrote: > I'm not sure about gyroscopes, since they can't be done on a chip, but > there is other techniques to get G forces and direction... Cool things can be done with MEMS. Introduced in December 2002 now scheduled for obsolescence http://www2.electronicproducts.com/Gyroscope_on_a_chip_is_industrys_first-article-DECHL3-DEC2002.aspx Replaced by http://www.analog.com/en/sensors/inertial-sensors/adxrs613/products/product.html at ~$30/each ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Motion sensors for navigation
On 23 March 2010 22:32, David Earl wrote: > Yes, obviously. The problems we have are exactly the ones they are trying to > solve though - urban canyons and tunnels - where we lose the GPS accuracy I think using a mobile phone equiped with A-GPS and/or wifi positioning would still be more accurate... ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Motion sensors for navigation
On Tue, 23 Mar 2010, Emilie Laffray wrote: > They might when they have some working prototypes :) I can't imagine the > calculation problem that they would be getting using 6 motions sensors (3 > accelerometers, and 3 gyroscopes). > My son can answer with great accuracy the accuracy question of an inertial navigation system and I quote from his honours paper 8 INS Results 8.1 Accuracy The accuracy from the INS was very low. In the green trail, the simplest of all the trails and the only one reduced from the INS data because of the difficulty in performing the reduction, there was a 65km error. The distance between the start and end of the trail is only 270m. This makes an error of approximately 240 times the distance traveled. This error did behave in the way expected from the INS. It was mostly in the distance covered, with the shape of the trail and the corners represented in the trail The error also increased exponentially with time, leading to much greater errors at the end of the trail then at the beginning. This also makes reduction of the data much more difficult as a linear fit of the data to the GPS data will not remove the errors, but will simply rearrange them. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Motion sensors for navigation
On 23 March 2010 22:35, Emilie Laffray wrote: > Mobile phones with gyroscopes?? I didn't realize mobile phones were having > so many complex and expensive pieces in them. Most phones have now > accelerometers with 3 Axis enabled; I just didn't realize some had > gyroscopes too. I'm not sure about gyroscopes, since they can't be done on a chip, but there is other techniques to get G forces and direction... AK8976A - 3-axis Accelerometer, 3-axis Magnetic field sensor (compass), Orientation sensor, Temperature sensor ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Motion sensors for navigation
On 23 March 2010 13:29, John Smith wrote: > On 23 March 2010 22:07, Emilie Laffray wrote: > > They might when they have some working prototypes :) I can't imagine the > > calculation problem that they would be getting using 6 motions sensors (3 > > accelerometers, and 3 gyroscopes). > > There is quite a few mobile phones with chips that have all 6 inputs... > Mobile phones with gyroscopes?? I didn't realize mobile phones were having so many complex and expensive pieces in them. Most phones have now accelerometers with 3 Axis enabled; I just didn't realize some had gyroscopes too. Emilie Laffray ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Motion sensors for navigation
On 23/03/2010 12:21, John Smith wrote: > On 23 March 2010 21:56, David Earl wrote: >> I wonder whether they might be interested in offering us some units for >> testing? > > Using inertial navigation the accuracy deteriorates considerably over time. > > http://en.wikipedia.org/wiki/Inertial_navigation Yes, obviously. The problems we have are exactly the ones they are trying to solve though - urban canyons and tunnels - where we lose the GPS accuracy for a short while. I don't think they're suggesting they are a substitute for GPS, just to augment it where GPS can't reach. If they are looking at military applications, the accuracy has to be an order of magnitude better than we would need as is their GPS. David ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Motion sensors for navigation
On 23 March 2010 22:07, Emilie Laffray wrote: > They might when they have some working prototypes :) I can't imagine the > calculation problem that they would be getting using 6 motions sensors (3 > accelerometers, and 3 gyroscopes). There is quite a few mobile phones with chips that have all 6 inputs... ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Motion sensors for navigation
On 23 March 2010 21:56, David Earl wrote: > I wonder whether they might be interested in offering us some units for > testing? Using inertial navigation the accuracy deteriorates considerably over time. http://en.wikipedia.org/wiki/Inertial_navigation ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Motion sensors for navigation
On 23 March 2010 12:56, David Earl wrote: > I thought this was an interesting little article: > > http://bit.ly/alE861 > > ( > > http://www.newscientist.com/article/mg20527524.500-motion-sensors-could-track-troops-when-gps-cuts-out.html > ) > > I wonder whether they might be interested in offering us some units for > testing? > They might when they have some working prototypes :) I can't imagine the calculation problem that they would be getting using 6 motions sensors (3 accelerometers, and 3 gyroscopes). Emilie Laffray ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
