Angular rate sensors, ARS, are devices that directly measure angular rate, without integration in conditioning electronics.
Gyroscopes also measure angular rate. Generally gyroscopes are able to measure a constant rotation rate, while rate sensors also include devices with a low
cut off frequency that is other than zero.
Technologies
Main technologies for rate sensors:
* Electromechanical (various types)
*
Vibrating structure gyroscope
A vibrating structure gyroscope, defined by the IEEE as a Coriolis vibratory gyroscope (CVG), is a gyroscope that uses a vibrating structure to determine the rate of rotation. A vibrating structure gyroscope functions much like the halteres of ...
s, including MEMS gyroscopes
*
Ring laser gyroscope
A ring laser gyroscope (RLG) consists of a ring laser having two independent counter-propagating resonant modes over the same path; the difference in phase is used to detect rotation. It operates on the principle of the Sagnac effect which shift ...
s
*
Fibre optic gyroscope
A fibre-optic gyroscope (FOG) senses changes in orientation using the Sagnac effect, thus performing the function of a mechanical gyroscope. However its principle of operation is instead based on the interference of light which has passed throu ...
s
*
MHD sensors, based on the
magnetohydrodynamic
Magnetohydrodynamics (MHD; also called magneto-fluid dynamics or hydromagnetics) is the study of the magnetic properties and behaviour of electrically conducting fluids. Examples of such magnetofluids include plasmas, liquid metals, ...
effect
* Electrochemical sensors (based on
molecular electronic transducer (MET) technology)
MET sensors
There are two types of MET rate sensors that directly measure angular rate: one that is able to measure constant angular rate (DC sensitive) and one that is not.
A non–DC-sensitive angular rate sensor consists of a
toroid
In mathematics, a toroid is a surface of revolution with a hole in the middle. The axis of revolution passes through the hole and so does not intersect the surface. For example, when a rectangle is rotated around an axis parallel to one of its ...
filled with a special
electrolyte that moves when the device is rotated about its measurement axis. When this happens the electrolyte flows through the sensing element, which is rigidly fixed inside the channel, and the motion is detected. The output signal is proportional to the angular rate due to internal integration that occurs inside of the sensing element. The cutoff frequency for measurements can be as low as 0.005 Hz.
A DC-sensitive angular rate sensor or gyroscope has a more complex design and uses measurement of
Coriolis acceleration
In physics, the Coriolis force is an inertial or fictitious force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the ...
to determine angular rate..
Uses
Angular rate sensors are used in a variety of applications including vehicle handling, crash, biomechanics, and high-rate ballistics testing.
Modern cars typically contain a
Yaw-rate sensor which determines how far off-axis a car is "tilting" in a turn.
References
Laboratory equipment
Sensors
{{tech-stub