they are generally rate gyro's as in they return the rate of change of rotation think of them as an acceleromiter for rotation ----- Original Message ----- From: "Robert Ussery" To: Sent: Saturday, July 26, 2003 10:55 AM Subject: Re: Dynamic tilt angle sensor > Never mind... I guess they're real gyros. Pretty cool! Thanks a lot! I > thought Analog only made accelerometers. > Not a bad price either... I only really need roll axis control, since yaw's > not too important and can controlled with a tilt sensor set up as a turn > coordinator, and pitch is controlled by airspeed. > > > > - Robert > > > ----- Original Message ----- > From: "Robert Ussery" > To: > Sent: Friday, July 25, 2003 6:48 PM > Subject: Re: [PICLIST] Dynamic tilt angle sensor > > > > Are these gyroscopes or accelerometers? > > > > - Robert > > > > > > ----- Original Message ----- > > From: "M. Adam Davis" > > To: > > Sent: Friday, July 25, 2003 5:18 PM > > Subject: Re: [PICLIST] Dynamic tilt angle sensor > > > > > > > There are lots of solid state gyros out there: > > > http://www.analogdevices.com/index_noflash.html > > > Click on MEMS Technology, Selection Tables, and iMEMS. Gyroscopes > > > > > > > > %253D%25252D1%2526ContentID%253D14642%2526level1%253D212%2526level2%253D%252 > > 52D1%2526level3%253D%25252D1,00.html> > > > for two examples of solid state gyros. > > > > > > Of course, they are $33[USD] each, and you need three for a full three > > > axis gyro, but it's still under the $100 you specified originally... :-) > > > > > > -Adam > > > > > > > > > Robert Ussery wrote: > > > > > > >Thanks, Matt. > > > >I'll give that a try. My only concern with keeping track of bank > through > > > >accelerometers is their drift and lack of sensitivity to low roll > rates. > > I > > > >think it should work, however, as long as roll rates are kept within > the > > > >specs of the accelerometer. > > > >Laser ring gyro's would be great except for $$... Roll my own, mebbe? > :O) > > > > > > > >- Robert > > > > > > > > > > > >----- Original Message ----- > > > >From: "Matt Redmond" > > > >To: > > > >Sent: Friday, July 25, 2003 10:00 AM > > > >Subject: Re: [PICLIST] Dynamic tilt angle sensor > > > > > > > > > > > > > > > > > > > >>Sorry - forgot to change the subject of my earlier reply! > > > >> > > > >>Robert: What you are looking for is gyro inclinometer - > > > >>probably a solid-state gyro inclinometer. Do a Google > > > >>search for "solid state gyro" and/or "gyro inclinometer" > > > >>and you will likely get a bazillion hits. The trick is > > > >>finding one that is cheap! > > > >> > > > >>You /could/ use an accelerometer like the one suggested > > > >>earlier. You would have to keep track of the current bank > > > >>angle (in your microcontroller) at all times. For example, > > > >>the accelerometer won't tell you you /are in/ a standard > > > >>rate turn - but it will have told you earlier that you > > > >>entered it. Since it hasn't told you that you returned to > > > >>wings-level, you know you're still in the turn. AFAIK, > > > >>laser-ring accelerometers were the standard devices used > > > >>in autopilots for many years until GPS was approved > > > >>recently. > > > >> > > > >>-matt > > > >> > > > >> > > > >> > > > >> > > > >>Sorta, except that it's (AFAIK) just an accelerometer and > > > >>won't tell you > > > >>angle relative to the horizon in a dynamic situation. > > > >>I.e., if you're in a > > > >>coordinated 1 G turn, it'll tell you you're level, whereas > > > >>you will have > > > >>approximately a 60 degree bank. My question dealt with how > > > >>you can measure > > > >>tilt in a dynamic, not a static situation. > > > >>In "real" aircraft, a mechanical gyro remains level with > > > >>the horizon, no > > > >>matter what position the airframe takes relative to the > > > >>horizon. I want to > > > >>duplicate this in a UAV without the expense of a full-up > > > >>mechanical gyro > > > >>system. > > > >> > > > >> > > > >> > > > >>- Robert > > > >> > > > >> > > > >>-- > > > >> > > > >>http://www.piclist.com#nomail Going offline? 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