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


Coriolis effect is also used in Mass Flow meters. They use an oscillator and
the different mass and flow rate changes the oscillations. Measurement is
taken from the voltage required to maintain a determined vibration rate.
An easy to see example of this is if you have a wand shower head with a hose
to the head part. With the water flowing, increase or decrease the water flow
and watch the hose. It will twist as the flow changes.

Dale Davies