Glossary

The error received when a drive or control has attempted an illegal process and becomes disabled.

A signal which is transferred from the output back to the input for use in a closed loop system.

A method that "pre-compensates" a control loop for known errors due to motor, drive, or load characteristics to improve response. It depends only on the command, not the measured error.

A light wave system that utilizes a glass or plastic fiber guide to transmit light to a control source where the optic intensity is linearly translated into current or is used to determine the open/close state of a current path.

A process control network used for interconnecting sensors, actuators, and control devices to one another, as defined by ISA standard S50.02.

The ability of a drive to restart a spinning motor. This is normally done by sampling the motor speed, encoder input, or back EMF to restart the motor from the speed at which it is coasting.

The ability of a motion controller to swap virtual encoders instantly making advanced synchronizing features possible.

The difference between the commanded position of an axis and its actual position. The amount of Following Error present varies with the speed of the axis. The amount of following error allowed can be adjusted through the KV parameter.

The ratio of RMS current to average current. This number is a measure of the current ripple in a SCR or other switch-mode type of drive. Since motor heating is a function of RMS current while motor torque is a function of average current, a form factor greater than 1.00 means some fraction of motor current is producing heat but not torque.

Refers to a motion system which can operate in all four quadrants; i.e., velocity in both directions and torque in either direction. This means that the motor can accelerate, run and decelerate in either direction.

A motor format which consists of only the stator and rotor provided such that a manufacturer can directly incorporate it into the framework of his machine and eliminate the need for couplings, shafts, or mechanical transmissions.

A resistance to motion caused by contact with a surface. Friction can be constant with varying speed (Coulomb friction) or proportional to speed (viscous friction).