Eastman-kodak Company

Kenneth A Lindsay

Mark Steven Janosky

David Andrew Johnson

James T Stoops

A slow-speed servomechanism includes a motor for driving a load; a direct drive transmission between the motor and the load; an incremental optical encoder connected to the load, the encoder having analog sine and cosine outputs; an analog to digital converter for converting the sine and cosine analog values to digital values; and a digital controller, connected to the motor and the analog to digital converter, for controlling the motor. The digital controller includes an angle decoder responsive to the sine and cosine digital values from the analog to digital converter to produce a relative position count indicating a position within one sine and cosine signal pair, a cycle counter responsive to the relative position count for producing an absolute position count within the operating range of the servomechanism by determining which sine cosine pair is being measured, the angle decoder and cycle counter performing at least four angle decodes within each encoder sine and cosine cycle; a command generator responsive to a user defined desired motion of the load to output a desired count; a phase detector responsive to the absolute position count from the cycle counter and the desired count from the command generator to produce an error signal, and a compensation filter responsive to the error signal for generating a motor driving command.

Slow-speed servomechanism

A media transport system for controlling the position and velocity of media in a document production apparatus marking engine having a media positioning system driven by a motor, includes a motion control loop to control the motor; a sensor adapted to detect the position of the media and to create a trigonometric signal characteristic of the position of the media, the trigonometric signal comprising frequency and phase components; a resolver electronics subsystem adapted to trigonometrically process the trigonometric signal to create a resolved signal; and means for comparing the resolved signal to a reference clock signal of predetermined frequency and phase to provide an error signal used to control the motor that drives the media positioning system. The trigonometric signal may include a sine portion and a cosine portion. The sine portion of the trigonometric signal is sin(.omega..sub.e *t+.phi..sub.e) and the cosine portion of the trigonometric signal is cos(.omega..sub.e *t+.phi..sub.e); where .omega..sub.e is the trigonometric signal frequency component, .phi..sub.e is the trigonometric signal phase component, and t is the time. The resolver electronics subsystem may include a first multiplier adapted to output the product of the sine portion of the trigonometric signal and a reference cosine command cos(.omega..sub.r *t+.phi..sub.r); a second multiplier adapted to output the product of cosine portion of the trigonometric signal and a reference sine command sin(.omega..sub.r *t+.phi..sub.r), where .omega..sub.r is the frequency of the reference command and .phi..sub.r is the phase of the reference command; and means to add the outputs of the first and second multipliers.

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Brockport, NY, United States of America

Kenneth A Lindsay