This one needs a little clarification. Kart racers have been using accelerometer based data acquisition systems with trackside beacons for accurate lap times for a while now. The newer ones have GPS, but I don't think they always did. The granularity of the data is really fine. The instruments retail for between $300 and $700 and sell in small quantities compared to, say,... cellular phones. With micromachining the accelerometer does not have to be expensive to be remarkably good. Anyway for a sense of the progression from accelerometers to GPS, read down to the bottom of this page:
http://www.edgekart.com/store/gauges/mychron4.htm Here is another supplier: http://www.digatronusa.com/products-karts.shtml An accelerometer will make a scribble with no reference to the track geometry, but with decent calibration, at a store entrance, an accelerometer emulating a GPS can find item beacons on store shelves (note: the phone behaves as if the item is sending a beacon based on a coordinate difference between phone and item and an emulated compass) even when no GPS [signal] is present. This works for vendor booths at trade shows too, but the stable platform of a grocery cart may be needed for early versions just because signal to noise is so good compared to being on a person. On Jul 8, 10:36 am, "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote: > Thank you for the AGPS link. > I agree that Cell ID is the right granularity for a lot of useful > solutions. And appreciate the 10cm precision instrument size. > > I have a friend with a Garmin wrist watch sized GPS that resolves to > about 3 ft by looking at the data from lunch run departures and > returns on the same sidewalk. That is good enough to have an item > beacon. > > The accelerometer can theoretically simulate position data as you walk > around in a store. If you calibrate your cart on a yellow arrow at the > entrance... three radios in the corners of the store ceiling could > give you 'particle cell' tower position data. Maybe at a low enough > frequency to not get blocked by buildings. > > So I guess the idea is: An item beacon can be implemented in several > ways, 1) an expensive, 2+ dollar, accelerometer that integrates twice > to get accumulated displacement (if mounted to a cart that might > actually work), and 2) event or location based radio system on the > smaller than micro scale that help a market organizer provide guidance > to customers at trade shows or other marketplaces. > > I don’t' know if you have ever struggled to find a booth at SuperComm > or NextComm or whatever it is. They could get more money for their > back alley booths if folks could choose an itinerary or list of > destinations from the web and let micro radios in the corner locate > and android phones guide them to booth by booth by presenting merchant > beacons in a logical order. The calibration spot would be for > promotional purposed mostly. > > Does anyone have an accelerometer to GPS utility for indoor mapping > yet? > Is the i-phone accelerometer good enough to do this? > > On Jul 8, 9:22 am, whitemice <[EMAIL PROTECTED]> wrote: > > > > > Android will be restricted by the limitations of the hardware on which > > it runs. Right now 10cm is achievable with a device the size of a > > toolbox, which can average out multiple input signals over time. > > > You are more likely to find an implementation of “Assisted GPS” on an > > Android device:http://en.wikipedia.org/wiki/Assisted_GPS > > > To get an idea of performance, have a go on a Nokia N95 - You will > > find that: > > - It doesn’t work indoors (shooting down the in-store use case). > > - Cold start times can be excessively long. > > - Detrimental to power consumption (if in constant use) > > > Performance on handsets is still inferior to dedicated GPS devices. > > Don’t expect massive improvements in the near future as Mores law > > doesn’t apply to mobile devices. > > > I blogged this in more detail here (half way down the > > post):http://blog.zedray.com/2008/05/16/android-developer-challenge-critique/- > > Hide quoted text - > > - Show quoted text - --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Android Discuss" group. To post to this group, send email to android-discuss@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/android-discuss?hl=en -~----------~----~----~----~------~----~------~--~---
