IEEE 528-2019 pdf download

IEEE 528-2019 pdf download.IEEE Standard for Inertial SensorTerminology.
anisoinertia: (A) (accelerometer) A relationship among the principal axis moments of inertia of an accelerometer pendulum in which the moment of inertia about the output axis differs from the difference of the moments of inertia about the other two principal axes. This inequality causes the effective centers of mass for angular velocity and for angular acceleration to be physically separated. In a system in which the accelerometer is modeled as though it were located at the effective center of mass for angular acceleration, there will be an offset in accelerometer output proportional to the product of the angular rates about the input and pendulous axes. Anisoinertia may be expressed as the magnitude of the actual separation in units of length, or as a compensation term expressed as (m/s2)/(rad/s)2 in SI units.5 Anisoinertia, in this usage, differs from standard physical definitions, but it describes a real effect that is closely analogous to the effect of the same name in gyros. The effect is most easily described in a pendulous accelerometer, built can also be seen in a nominally translational proof mass accelerometer that has sufficient angular elastic compliance to emulate a pendulous axis. (B) (mechanical gyro) The inequality of the moments of inertia about the gimbal principal axes. When the gyro is subjected to angular rates about the input and spin axes, and the moments of inertia about these axes are unequal, a torque is developed about the output axis that is proportional to the difference of the inertias about the input and spin axes multiplied by the product of the rates about these two axes.
anti-lock means (laser gyro): Mitigation of lock-in effects by inducing a nonreciprocal phase (or frequency) shift between the counter-propagating beams.
NOTE—This can be accomplished by mechanical or magneto-optical means.
anti-lock residual (laser gyro): Output noise remaining after compensation for anti-lock means.
ARW: See: angle random walk.
attitude storage (mechanical gyro): The transient deviation of the output of a rate-integrating gyro from that of an ideal integrator when the gyro is subjected to an input rate. It is a function of the gyro characteristic time (see Figure 1). See: float storage; torque-command storage.
NOTE—Control of operating conditions may address sensitivities such as temperature, magnetic fields, and mechanical and electrical interfaces, as necessaiy.
bias asymmetry (gyro, accelerometer): The difference between the bias for positive and negative inputs, expressed as radls (gyro) or rn/s2 (accelerometer) in SI units.7
bias instability (gyro, accelerometer): The random variation in bias as computed over specified finite sample time and averaging time intervals. This nonstationary (evolutionary) process is characterized by a I/f power spectral density. It is expressed as rad/s (gyro) or rn/s2 (accelerometer) in SI units.
biasing (laser gyro): The action of intentionally imposing a real or artificial rate into a laser gyro to avoid the region in which lock-in occurs.
binary torquing (mechanical gyro, accelerometer): A torquing mechanization that uses only two torquer current levels that are usually positive and negative of the same magnitude; no sustained zero current or off condition exists. The positive and negative current periods can be either discrete pulses or duration- modulated pulses. In the case of zero input (acceleration or angular rate), a discrete pulse system will produce an equal number of positive and negative pulses. A pulse-duration-modulated system will produce positive and negative current periods of equal duration for zero input. Binaiy torquing delivers constant power to a sensor torquer (as compared to variable power ternary torquing) and results in stable thermal gradients for all inputs.
caging (mechanical gyro): The process of orienting and mechanically locking one or more gyro axes or gimbal axes to a reference position.
capturing (mechanical gyro, accelerometer): The use of a torquer (forcer) in a servo ioop to restrain a gyro gimbal. rotor, or accelerometer proof mass to a specified reference position.
case (gyro, accelerometer): The housing or package that encloses the sensor, provides the mounting surface, and defines the reference axes.
characteristic time (mechanical gyro, accelerometer): The time required for the output to reach 63% of its final value for a step input.
NOTE—For a single-degree-of-freedom, rate-integrating gyro, characteristic time is numerically equal to the ratio of the float moment of inertia to the damping coefficient about the output axis. For certain fluid-filled sensors, the float moment of inertia may include other effects, such as that of transported fluid.
coast time (mechanical gyro): See: run-down time.