AI-4
PRECESSION VECTOR—In a gyro, a vector representing the angular change of the spin axis
when torque is applied. The precession vector represents the axis about which precession
occurs.
PRESTANDARD NAVY SYNCHROS—Synchros that are designed to meet Navy, rather than
servicewide, specifications.
RATE GYRO—A gyro used to detect and measure angular rates of change.
RESOLVER—A rotary, electromechanical device used to perform trigonometric computations
by varying the magnetic couplings between its primary and secondary windings. It is
generally used in circuits that solve vector problems, such as analog computers and
conversion equipment. The resolver solves three different type problems: (1) resolution—
separating a vector into two mutually perpendicular components; (2) composition—
combining two components of a vector to produce a vector sum; (3) combination—the
process of resolution and composition taking place simultaneously.
RESULTANT MAGNETIC FIELD—The magnetic field produced in a synchro by the
combined effects of the three stator magnetic fields.
RIGIDITY—The tendency of the spin axis of a gyro wheel to remain in a fixed direction in
space if no force is applied to it.
ROTOR—The rotating member of a synchro that consists of one or more coils of wire wound on
a laminated core. Depending on the type of synchro, the rotor functions similar to the
primary or secondary winding of a transformer. In a gyro, the rotating member is sometimes
called a gyro wheel.
SCALING FACTOR—The term used to describe the use of unequal resistors in a servo's
summing network to compensate for differences between input and output signal levels.
SERVO AMPLIFIER—An ac or dc amplifier used in servo systems to build up signal strength.
These amplifiers usually have relatively flat gain versus frequency response, minimum phase
shift, low output impedance, and low noise level. The dc amplifier is subject to excessive
drift and is relatively unstable. However, the ac amplifier is considered drift free and has a
constant dynamic gain over a variety of operating points.
SERVO MOTOR—An ac or dc motor used in servo systems to move a load to a desired
position or at a desired speed. The ac motor is usually used to drive light loads at a constant
speed, while the dc motor is used to drive heavy loads at varying speeds.
SERVO SYSTEM—An automatic feedback control system that compares a required condition
(desired value, position, etc.) with an actual condition and uses the difference to adjust a
control device to achieve the required condition.
SIGNAL—The angle through which a synchro transmitter rotor is mechanically turned.
SPIN VECTOR—In a gyro, a vector representing the angular velocity of the gyro rotor. The
spin vector lies along the spin axis of the rotor.
