http://groups.google.com/group/openintents-subversion/browse_thread/thread/d13ecf06593d1cd4/160f00916c194a0d?hl=en&lnk=st&q=OpenIntent+compass#160f00916c194a0d
I can't follow the thread to figure out how he is deriving a compass heading. James On May 19, 6:52 am, Alex Pisarev <[EMAIL PROTECTED]> wrote: > As far as I remember, OpenIntent's Sensor Simulator managed to emulate > compass somehow, however, didn't look details. > > Regards, > Alex > > On May 19, 3:33 pm, "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote: > > > > > Hi James, > > > This is helpful. Thank you. It is good to know someone is thinking > > about this. After reading the IEEE abstract, a little clarification on > > use is always helpful. > > > Our applications are eyes free, because the phone should not be > > competing for those revenue generating resources. So use will happen > > with the phone stored on the person’s body, say, in a shirt pocket, > > held to the person's ear, or on their belt. The compass needs to work > > no matter how the phone is oriented. The IEEE abstract seemed unclear > > on how it would work in a handheld device. It would be great for cars, > > though. With the two accelerometers, there is a calibration routine > > where a person wears the phone normally and walks in one direction. 10 > > ft should be enough to get enough calibration to be useful. It can > > recalibrate in the background and alarm or adjust ... > > > Sensor Fusion is a new word for me. Differential sensors of finite > > resolution have been around for a long time. Consider the roach, or > > any bug with antennae. They sample air at distant points allowing the > > organism to select a direction. The longer the antennae, the smaller > > the gradient the organism can detect with sensors of a fixed > > resolution. Long antennae help folks figure out what is going on. > > Sampling acceleration at distant points is going to give you better > > information on angular velocity and acceleration (how fast you are > > spinning) than using a single sensor in the same way. > > > Thank you for pointing out that radio field interaction can provide > > information... since a human body can influence that, it is probably > > good to not rely on that method. Two sensors a fixed distance apart > > should require little attention and provide good results across many > > devices once it is engineered. > > > My job is to show why it is worthwhile to spend that dollar for > > pedestrians who don’t read maps. Android has the tools to do that, > > even in today’s SDK. > > > On May 18, 7:48 am, James <[EMAIL PROTECTED]> wrote: > > > > A MEMS chip can be a collection of sensors (temperature, accelerometer > > > (x,y,z), atmospheric pressure, Hall effect sensor (compass), ...) all > > > built into the same chip. In mass production the chip could be > > > relatively inexpensive. > > > >http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel5/20/35967/017046.... > > > > However, an Android shortcut would be to use the GPS sensor and your > > > relative direction of travel to produce a compass bearing over 100 > > > feet of uniform travel. For each model of cell phone the antenna > > > sensitivity changes as you rotate the cell phone about a point. This > > > could potentially be tied in with relative position movement to > > > estimate a compass bearing about a point. > > > > But as I said, the lookup table would be different for each model of > > > cell phone. > > > > This type of engineering where you take two sensors with low > > > resolution to combine their results to provide greater resolution is > > > called "Sensor Fusion". > > > > Basically a cell phone antenna signal does NOT have the same signal > > > profile when you rotate left versus rotate right. This can be > > > capitalized upon to determine the relative bearing of which the > > > compass is facing. Coupled with the cell phone GPS the relative > > > bearing can be referenced to the true bearing. A lookup table can > > > provide a correction factor and thereby produce Magnetic Bearing; vis > > > vi Compass. > > > > James Dunn > > > Table of Contents - Similar Insights related to technology > > > applicationshttp://blog.360.yahoo.com/jamesbdunn?p=207 > > > > On May 15, 9:23 pm, "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote: > > > > > I have no idea how much a cell phone with a compass costs. I don't see > > > > why it would be expensive if there were enough of a market to micro > > > > machine it like all those tiny mirrors. > Who knows these answers? > > > > > Thanks, > > > > Ed- Hide quoted text - > > > > - Show quoted text -- Hide quoted text - > > > - Show quoted text -- 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 [email protected] 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 -~----------~----~----~----~------~----~------~--~---
