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Glossary of Terms
Ndrive HL User’s Manual
A-8 www.aerotech.com
(TIR)
contact with the part surface during one full revolution of the part
about its axis of rotation.
Tuning
In a servo system, the process of optimizing loop gains (usually
PID terms) to achieve the desired response from a stage or
mechanism from an input command.
Unidirectional
Repeatability
See Repeatability
Velocity Command
Motor driver or amplifier configuration where the input signal is
commanding motor velocity. Motors with analog tachometers are
normally driven by this driver configuration.
Wobble
An irregular, non-repeatable rocking or staggering motion of the
table top of a rotary stage. Wobble is defined as an angular error
between the actual axis of rotation and the theoretical axis of
rotation.
Yaw (of travel)
Rotation about the vertical axis, perpendicular to the axis of
travel. Angular movement (error) that affects straightness and
positioning accuracy.
Yaw Error
Positioning error resulting from a yaw motion.
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