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Position Servo Utilizing Position Reference Clock

IP.com Disclosure Number: IPCOM000085606D
Original Publication Date: 1976-May-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Barela, DA: AUTHOR [+3]

Abstract

The device and procedure described herein provides an implementation of a closed-loop servo system which can be made to follow some desired trajectory.

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Position Servo Utilizing Position Reference Clock

The device and procedure described herein provides an implementation of a closed-loop servo system which can be made to follow some desired trajectory.

Fig. 1 is both an implementation of a hardware version and a microprocessor implementation. In Fig. 1, the circuits (shown in block diagram form) encircled by block 10 would be replaced by a microprocessor. Incidentally, block 10 is a representation of the microprocessor.

Fig. 2 is a sketch of the trajectory that the servo will follow.

The hardware implementation that makes up the drive signal to motor 14 is comprised of reference voltage path A, which is an open-loop branch whose purpose is to apply a precalculated voltage profile to motor 14 via amplifier 12. If all system parameters are at their nominal values, the reference voltage derived from reference voltage path A would alone drive the system along the desired trajectories. Positional error path 13 is derived from the closed-loop portion of the servo system, and its magnitude is proportional to the difference between the position reference and the actual output position.

Referring to Fig. 1, the feedback signals on terminal 16 and terminal 18 are digital information derived from a two-phase digital tachometer 20. The problem therefore is to develop a digital signal Pr(t) which is compatible with the digital system.

Fig. 3A shows a desired continuous output position trajectory denoted by Pdo(t). The vertical axis of the plot corresponds to position and has been divided into incremental position steps of Delta. Delta corresponds to the inc...