Since most solid state, so called gyros, if not all use a capacitor
   bridge circuit to sense acceleration and this is how they work.

   The mass is seeing the one G acceleration force due to gavity
   and is deflected downward. That means the spacing between the plates
   of C1 gets larger and the spacing of C2 gets smaller.

   As the spacing of the plates of a capacitor get larger
   the capacitance is reduced. When the spacing gets smaller
   the capacitance is increased.

   Think of a capacitor as a variable resisters for waves.

   There is an oscillator that supplies a constant amplitude  sine wave to the device.

   The amplitude of the wave coming out of this circuit will
   then be proportional to the number of G's the mechanical circuit is subjected
   too.

   Very high frequencies are used as these capacitors are tiny to say the least.
   The basic capacitance is on the order of only one pico farad.

   The wave amplitude coming out can be rectified or converted to DC and
   then fed to an A to D for computer input. Use four of them
   mounted equally spaced in a circle and you have a angular rate sensor.

   This is an extremely simple idea and it is easy to make.
   One can make their own, in any shop, using nothing but hand tools,
   vastly scaled up from what one finds in a MEMS chip.

   Paul Lamar


  It seems that you are discounting the sensors based on vibrating beam and the Coriolis effect.  Not sure why..  These
are the sensors that actually act like gyroscopes.

  http://m.sensorsmag.com/sensors/acceleration-vibration/an-overview-mems-inertial-sensing-technology-970


  Regards,

  Matt-

  Again they are misusing the term "gyroscope" for marketing purposes IMHO. A real gyroscope is a 3D device. A change
  in the Z axis of the real gyroscope results in a force in the X or Y axis. You get both roll and
  pitch information from one device.

  "As a result, the gyroscope[???] provides accurate angular rate sensing for rate changes from very small
  to very large, with minimal errors from short- or long-term drift."

  These are plainer devices hence they are angular rate sensors. It takes two and computer
  integration to get roll and pitch information. The beam deflection they are talking about
  here can be sensed by the same bridge capacitor electronics.

  http://en.wikipedia.org/wiki/Coriolis_effect

  "In physics, the Coriolis effect is a deflection of moving objects when they are viewed in a rotating reference frame.
In a reference frame with clockwise rotation, the deflection is to the left of the motion of the object; in one with
counter-clockwise rotation, the deflection is to the right."

  Note: no mention is made of a 3D system.

  Also they are not telling you how they sense the deflection of the sensing beam.


  Paul Lamar



http://en.wikipedia.org/wiki/Vibrating_structure_gyroscope


Matt-


IMHO another misuse of the term gyroscope.

http://en.wikipedia.org/wiki/Gyroscope

Paul Lamar


Cool demo:

ATM 9 axis motion sensor EVB
http://www.youtube.com/watch?v=Ak7w87oVTBk

Aiken Labs has the module for $300.

I'd expect prices to rapidly drop in the coming year.

Now only if I could get that FLIR camera for $1000.

Tom Walter