The accelerometers that you have worked with have been piezoelectric and do not respond to gravity. I have used an accelerometer design which uses a quartz plate deposited with metal, which has a quartz hinge specifically designed to flex in one axis only. Capacitance is measured between both sides of the plate and a coil centers the plate to balance the capacitance. The current used to drive the coil is a direct measure of the amount of force acting on the plate. We used three orthogonally placed to measure the acceleration due to gravity in order to steer a drilling tool in three dimensional space. They were 'borrowed' from the aerospace industry. -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Ned Seith Sent: Saturday, August 25, 2001 12:10 AM To: PICLIST@MITVMA.MIT.EDU Subject: Re: [EE]: "Tilt-o-meter" for RC plane As I have worked with accelerometers for a few decades conducting product vibration and shock reliability tests, I was perplexed at the notion that an accelerometer would be deployed as a "Tilt-o-meter" or as a position sensor. An accelerometer is not a position sensor. An accelerometer provides a "spontaneous" output voltage that is proportional to a "change" in velocity. An accelerometer will provide useful voltage output for significant acceleration, de-acceleration, impact and vibration events. If a "sensitive" enough accelerometer were aboard the electric assisted glider during roll, pitch or yaw activity, only a "spontaneous" voltage with a duration of a few milliseconds would be output for a specific roll, pitch or yaw movement. This output voltage would be indicative of the velocity of the roll, pitch or yaw movement and would be absolutely useless in terms of position. If the accelerometer were "sensitive" enough, it would provide an output for a significant aircraft acceleration event. However, it is most likely that an accelerometer aboard a motorized model aircraft would provide an output that is directly proportional to the vibratory energy emanating from the motor. "I'd have to say that would be a lot of fun, even if the plane crashes!" Now, that's a job for an accelerometer, "impact"! Sincerely, Ned Seith Nedtronics 59 3rd Street Gilroy, CA 95020 (408) 842-0858 ned@nedtron.com >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> At 11:12 PM 8/23/01 -0600, you wrote: >At 06:53 PM 8/23/01 -0700, Wade Carpenter wrote: > >First thing I plan to do as far as PIC v/s Plane goes is to make a circuit > >to level out the wings in flight. i.e. if one wing dips, it will > >compensate. I'm not worried about controlling the actuators on the plane or > >anything like that (yet) but more about the sensor that is to sit in my > >feedback path. I need a "tilt-o-meter!" . I'm sure it's not called that! > >Try a 1-axis accelerometer mounted with the active direction at right >angles to the direction of flight. An ADXL105 would do the trick. Trouble >is, it's even more expensive than the mag sensor! > >Regards, >Wayne > >-- >http://www.piclist.com hint: To leave the PICList >mailto:piclist-unsubscribe-request@mitvma.mit.edu -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads