Sherborne Sensors A215/220 Series Single Axis Precision Servo Accelerometers0 pages

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A215-220 - Iss 8.doc
A215/A220 Series
Gravity Referenced
Linear Servo Accelerometers
Features
.. Available in ranges from ±1g to ± 20g
.. High resolution down to 0.05 mg
.. Closed loop force balance system
.. Flight qualified versions available
.. Self-Test facility
.. DC Input – DC Output
.. Manufactured to ISO 9001:2000
standards
.. 1g bias option to compensate for earth’s
gravity (A220 only)
Introduction
The Sherborne Sensors’ range of Servo Accelerometers
measure vector acceleration with high accuracy using a
closed loop force balance torquer mechanism.
All A200 Series Accelerometers operate as a closed-loop
torque balance servo system.
Refering to the illustration above, the pendulous mass ‘A’
develops a torque proportional to the product of its mass
unbalance and the applied acceleration. The movement of
mass ‘A’ is detected by position sensor ‘B’ whose output
signal is connected to a servo amplifier. The resulting
current is fed into the torquer motor ‘C’ which then
develops a torque exactly equal to, but directly opposed to
the initial torque from the pendulous mass ‘A’. Mass ‘A’
stops moving, assuming a position minutely differing from
it’s zero ‘g’ position. Simultaneously, the current to the
torquer motor is fed through a stable resistor to provide an
output voltage proportional to the applied acceleration.
The system is electronically damped by means of a phase
advancing network within the integrated servo amplifier.
By adjusting the parameters of the servo amplifier and
related electronic networks, the operating characteristics
of a servo accelerometer can be optimised to suit a
particular application.
In addition to the instruments offered in this bulletin
Sherborne Sensors design accelerometers for specific
applications. These custom designed units are often
manufactured and tested to conform to military standards.
Applications
.. Flight test monitoring
.. Accident data collection
.. Structural health monitoring
.. Flight simulators
.. Braking control on mass transit systems
.. Road bed analysis
.. Data acquisition systems
.. Low frequency analysis