Glossary

AC stands for Alternating Current which periodically reverses direction, in contrast to direct current (DC) that flows only in one direction. AC is the typical power source that comes 'out of the wall'. Single phase and three AC phases are standard.

AC Line Filter is a filter that connects to the incoming AC on a machine. Intended to keep the electrical noise produced in the machine from polluting the AC in the building.

AC Servo is a general term referring to a motor drive that generates sinusoidal shaped motor currents.

Acceleration is the rate at which something increases its velocity. Acceleration is usually measured in units of velocity change for each unit of time (inches/ second (velocity)/second (time)) and in this example would be written as in./sec/sec or in./sec2.

Accuracy is the relative status of something compared to its absolute or perfect value. In motion control this will most often be a position description. A command may be sent to move 4.0”. The accuracy of the system will be defined by how close to the absolute value of 4.0” the system can affect the move. Accuracy may be defined as a one-time incident or the average over a number of cycles or motions. Positioning accuracy will normally be defined in terms of deviation (+/- from theoretical) or limits (acceptable variation from theoretical: ie. 3.8”-4.2” define acceptable limits of variation around a theoretical point of 4.0”)

Active Front End is a front end processor which interacts with both upstream and downstream equipment and makes required changes based on the incoming and outgoing parameters and data, without external control.

Actual Position is the position of an axis relative to the commanded position. This may be the position at the end of the commanded move or the lag between command position at any point during the move and the actual position of the axis at that point. The latter is commonly referred to as Following Error.

For servo systems, Actuator is a device (such as a motor) that outputs mechanical motion using electricity as the power source.

Alarm is an indication that a monitored parameter is not within the prescribed acceptable range. Usually this is in the form of an output that can be used to initiate an operator warning or advisory, to generate a corrective action, or to cause a cessation of the operation underway.

The temperature of the cooling medium, usually air, immediately surrounding the motor or another device.

Ampere is the basic unit of electric current. In short “Amp” or “Amps”.

A servo system that utilizes analog control and feedback systems such as voltage variation, pressure changes etc. Analog servos are most commonly found in hydraulic and similar systems.

Analog signal is a communication within the system that is accomplished by means of a signal that varies in direct relation to the intensity or magnitude of the external quality being measured. Typical examples are a 0-10 volt motor control signal, a hydraulic pilot pressure, a pneumatic control pressure.

Angular accuracy is the measure of shaft positioning accuracy on a servo or stepping motor.

The specific major directions along which controlled movement occurs. Usually the number of these major directions employed in a specific machine and defined as follows: ● X: Linear motion in positioning direction ●Y: Linear motion perpendicular to positioning direction ●Z: Vertical linear motion ●A: Angular motion around X (roll) ●B: Angular motion around Y (pitch) ●C: Angular motion around Z (yaw)

Axis is a principal direction along which movement of a tool, component or workpiece occurs.