[android-discuss] Re: (D)GPS good to 10 cm
Having an accelerometer on a chip is a great idea. They are cheap, accurate and available on more and more phones: http://www.dimensionengineering.com/accelerometers.htm The problem is that you are trying to use them for inertial navigation, which is inherently complex, requires both orientation and acceleration sensing and some sort of position initialisation. Don’t forget that mobile software developers have to make do with *standard* hardware. http://en.wikipedia.org/wiki/Inertial_navigation_system I see that you are clutching at straws, trying to make your use case work. To that end, have you considered investigating Wi-Fi based positioning? http://www.spotigo.com/products-and-services/spotigo-wifi-based-positioning-solution/ Bluetooth can also be useful, but I won’t comment on that until I have been allowed to play with the actual Android API. ;-) --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
[android-discuss] Re: (D)GPS good to 10 cm
There are a lot of interesting use cases for sub 1m accuracy and/or indoor positioning on a mobile phone – hence I am following your ideas with interest. Your proposal as I understand it: If the communication API (at either the server or the client side) gives you access to signal strength and packet delay information, you may be able to get some idea of distance (but not direction?). This estimate would become less reliable as more walls and furniture get in the path of the signal. Communicating with two Wi-Fi transmitters (if this is possible on the client side?) with known positions and coverage areas, would give you two or more overlapping regions where the handset might currently be located. By fixing your results along known walking routes and integrating path data (from the accelerometer) you might be able to guestimate a user’s current position. With all these uncertainties, I think claims of sub 1m accuracy are overly optimistic (but not unachievable), although such a system could have other benefits. To the original question: the Android Wi-Fi API has not yet been released, so I can’t comment on how well your proposal might work on a real device. Also, I am also investigating using accelerometers for estimating position *inaccuracy* for my Snowball platform, which has significantly lower accuracy requirements: http://blog.zedray.com/snowball/ --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
[android-discuss] Re: (D)GPS good to 10 cm
whitemice, Your description is technically in focus in that we are looking at the same thing, I just want phone to use the accelerometer(s) to emulate 1 meter GPS and compass functions when no GPS or compass is available. 1.) So all the programming involves is: behavior is f(dx,dy,dz,orientation). The system provides the data from whatever costs the least. The function is already there on location, but accelerometer (inertial) estimates were not on the list of location service providers. This should be on the list with whatever caveats come with it (like requires consistent orientation since last known good). 2.) The other thing is that when data is bad and tower location cannot resolve exactly where the phones are I want the system to present choices in addition to precision estimates. The local program can have stored information about routes and history to pick from several possible positions. This will maintain continuity in the application whereas having precision suddenly go to a km with no more bearing data really blows up a pedestrian level program that requires a simulated compass. 3). Also, when comparing two poor signals (think like interpolating steam tables), the comparison needs to be done before any rounding. I want the phones to be able to share and compare raw data with each other without asking the system to make an independent (non- differential) estimate of where each is. If I am trying to locate someone and I cannot read a map, all I care about is relative position. The system can act like some systems engineer and insist on giving me only absolute data and throw the baby out with the bathwater, but it does not have to. In other words, android location services can be more robust than systems costing 4 times as much. This is a difference all customers will recognize when they do the inevitable side by side comparisons. Each time that happens Android takes share. ed (the systems engineer :-) On Jul 9, 7:05 am, whitemice [EMAIL PROTECTED] wrote: There are a lot of interesting use cases for sub 1m accuracy and/or indoor positioning on a mobile phone – hence I am following your ideas with interest. Your proposal as I understand it: If the communication API (at either the server or the client side) gives you access to signal strength and packet delay information, you may be able to get some idea of distance (but not direction?). This estimate would become less reliable as more walls and furniture get in the path of the signal. Communicating with two Wi-Fi transmitters (if this is possible on the client side?) with known positions and coverage areas, would give you two or more overlapping regions where the handset might currently be located. By fixing your results along known walking routes and integrating path data (from the accelerometer) you might be able to guestimate a user’s current position. With all these uncertainties, I think claims of sub 1m accuracy are overly optimistic (but not unachievable), although such a system could have other benefits. To the original question: the Android Wi-Fi API has not yet been released, so I can’t comment on how well your proposal might work on a real device. Also, I am also investigating using accelerometers for estimating position *inaccuracy* for my Snowball platform, which has significantly lower accuracy requirements:http://blog.zedray.com/snowball/ --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
[android-discuss] Re: (D)GPS good to 10 cm
(1) I’ve never seen someone trying to do inertial navigation on a phone, but it could work temporally if you have 3 axis orientation and acceleration sensitivity, or are only handling a 2D problem domain. I just checked and unfortunately it would require a lot of messing around to get JavaME access on my N95 to try this idea out. So I will wait for my first Android phone before experimenting with this idea. (2) Agreed, multiple positioning technologies make the solution more robust. (3) Agreed, but wait for the API to see what’s possible. Google have so far been very quiet with important technical details like this. What’s your background, are you going to try and build this? --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
[android-discuss] Re: (D)GPS good to 10 cm
...are you going to try and build this? Only if we have to. We are going to use the expensive handsets (that have accelerometers and compasses) as prototypes to show an end to end people coordination tool. On each step the use model will be made to work well using only those UI elements that will exist on the target hardware, a $50 handset. Then it is about persuading a handset manufacturer to make a pedestrian phone for ordinary people. Most of the early effort will be centered around making carpooled commutes efficient and attractive. The commutes will work with phones with no compass or accelerometer. Those instruments really come into play for queuing and organizing people on foot - which is one of the reasons carpools don't work right now. So yes, for an end to end tool the pedestrian stuff has to work. For pedestrian stuff to work you need reliable GPS like differential location with compass function. Inertial bridging to help a handset application select from location choices provided by a not quite sure tower triangulation service (an extension of this service where GPS coordinates are correlated to other parameters that phones know: http://googlemobile.blogspot.com/2008/06/google-enables-location-aware.html ) goes a long way toward making a phone that works for people on foot. On Jul 9, 11:03 am, whitemice [EMAIL PROTECTED] wrote: (1) I’ve never seen someone trying to do inertial navigation on a phone, but it could work temporally if you have 3 axis orientation and acceleration sensitivity, or are only handling a 2D problem domain. I just checked and unfortunately it would require a lot of messing around to get JavaME access on my N95 to try this idea out. So I will wait for my first Android phone before experimenting with this idea. (2) Agreed, multiple positioning technologies make the solution more robust. (3) Agreed, but wait for the API to see what’s possible. Google have so far been very quiet with important technical details like this. What’s your background, are you going to try and build this? --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
[android-discuss] Re: (D)GPS good to 10 cm
Am i really that illiterate? Firefox is better (-: 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 -~--~~~~--~~--~--~---
[android-discuss] Re: (D)GPS good to 10 cm
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 -~--~~~~--~~--~--~---
[android-discuss] Re: (D)GPS good to 10 cm
On Jul 8, 4:20 pm, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: 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. Have you driven a kart? These things GO. This means accelerometers have plenty to work with. A person pushing a shopping cart around a shop is probably not even raising sensor input levels over noise. --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
[android-discuss] Re: (D)GPS good to 10 cm
What's the noise? If the accelerometer cannot detect a device moving at a walking pace, then what's the real use for it? I'm not an expert, so asking the experts here :) On Wed, Jul 9, 2008 at 9:00 AM, JP [EMAIL PROTECTED] wrote: On Jul 8, 4:20 pm, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: 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. Have you driven a kart? These things GO. This means accelerometers have plenty to work with. A person pushing a shopping cart around a shop is probably not even raising sensor input levels over noise. -- take care, Muthu Ramadoss. http://cookingcapsules.com - nourish your droid. http://mobeegal.in - find stuff closer. --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
