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Servo Drive with Variable Reference

IP.com Disclosure Number: IPCOM000049659D
Original Publication Date: 1982-Jul-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Bateson, JE: AUTHOR [+4]

Abstract

The system using a single-chip microcomputer allows for a high degree of control (including adaptive control techniques) and controlled start/stop without expensive analog circuits. The pulse width modulated (PWM) amplifier provides power drive with high efficiency, and the digital control technique provides excellent velocity control.

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Servo Drive with Variable Reference

The system using a single-chip microcomputer allows for a high degree of control (including adaptive control techniques) and controlled start/stop without expensive analog circuits. The pulse width modulated (PWM) amplifier provides power drive with high efficiency, and the digital control technique provides excellent velocity control.

The system consists of a microcomputer with outputs going to a digital to analog converter (DAC). The output of the DAC provides a voltage to the drive circuitry. Attached to the motor is a two channel optical emitter with approximately symmetrical signals occurring in quadrature to one another. The emitter signals are sensed by the microcomputer. See the figure.

An error count is output from the microcomputer to the DAC to give a voltage for the drive circuitry. The time between emitter changes is detected, and this time value (in timer cycles) is compared to a reference time count which corresponds to the reference speed. This gives a speed error count value. The microcomputer outputs this error count which results in a change in the DAC voltage.

This scheme can be used for startIng, stopping and constant velocity motion. For starting and stopping, the reference time count is constantly changing (e.g., the times become shorter when velocity is increasing for starting). The time values for start and stop would be saved in a table with each emitter signal received causing the position in the tabl...