Glossary
Precision MicroControl Corp.
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Dual Loop Servo – A servo system that combines a velocity mode amplifier/tachometer with a position
loop controller/encoder. It is recommended that the encoder not be directly coupled to the motor. The
linear scale encoder should be mounted on the external mechanics, as closely coupled as possible to the
‘end effector’
Duty Cycle - For a repetitive cycle, the ratio of on time to total time:
Efficiency - The ratio of power output to power input.
Encoder - A type of feedback device that converts mechanical motion into electrical signals to indicate
actuator position or velocity.
End Effector – The point of focus of a motion system. The tools with which a motion system will work.
Example: The leading edge of the knife is the
end effector
of a three axis (XYZ) system designed to cut
patterns from vinyl.
Feed Forward - Defines a specific voltage level output from a motion controller, which in turn commands
a velocity mode amplifier to rotate the motor at a specific velocity.
Following Error - The difference between the calculated desired trajectory position and the actual position.
Friction - A resistance to motion caused by contacting surfaces. Friction can be constant with varying
speed (Coulomb friction) or proportional to speed (viscous friction).
Holding Torque - Sometimes called static torque, holding torque specifies the maximum external torque
that can be applied to a stopped, energized motor without causing the rotor to rotate continuously.
Inertia - The measure of an object's resistance to a change in its current velocity. Inertia is a function of
the object's mass and shape.
Kd - K is a generally accepted variable used to represent gain, an arbitrary multiplier, or a constant. The
lower case ‘d’ designates derivative gain.
Ki - K is a generally accepted variable used to represent gain, an arbitrary multiplier, or a constant. The
lower case ‘i’ designates integral gain.
Kp - K is a generally accepted variable used to represent gain, an arbitrary multiplier, or a constant. The
lower case ‘p’ designates proportional gain.
Limits - Motion system sensors (hard limits) or user programmable range (soft limits) that alert the motion
controller that the physical end of travel is being approached and that motion should stop.
MCAPI - The Motion Control Application Programming Interface - this is the programming interface used
by Windows programmers to control PMC's family of motion control cards.
MCCL - Motion Control Command Language - this is the command language used to program PMC's
family of motion control cards.
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